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47144 commits

Author SHA1 Message Date
Ahmad Fatoum
e016173f65 reboot: add support for configuring emergency hardware protection action
We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

In the general case, however, the driver detecting the issue can't know
what the appropriate course of action is and shouldn't be dictating the
policy of dealing with it.

Therefore, add a global hw_protection toggle that allows the user to
specify whether shutdown or reboot should be the default action when the
driver doesn't set policy.

This introduces no functional change yet as hw_protection_trigger() has no
callers, but these will be added in subsequent commits.

[arnd@arndb.de: hide unused hw_protection_attr]
  Link: https://lkml.kernel.org/r/20250224141849.1546019-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-7-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 23:24:14 -07:00
Ahmad Fatoum
96201a8a98 reboot: indicate whether it is a HARDWARE PROTECTION reboot or shutdown
It currently depends on the caller, whether we attempt a hardware
protection shutdown (poweroff) or a reboot.  A follow-up commit will make
this partially user-configurable, so it's a good idea to have the
emergency message clearly state whether the kernel is going for a reboot
or a shutdown.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-6-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 23:24:13 -07:00
Ahmad Fatoum
81cab0f94a reboot: rename now misleading __hw_protection_shutdown symbols
The __hw_protection_shutdown function name has become misleading since it
can cause either a shutdown (poweroff) or a reboot depending on its
argument.

To avoid further confusion, let's rename it, so it doesn't suggest that a
poweroff is all it can do.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-5-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 23:24:13 -07:00
Ahmad Fatoum
aafb1245b2 reboot: describe do_kernel_restart's cmd argument in kernel-doc
A W=1 build rightfully complains about the function's kernel-doc being
incomplete.

Describe its single parameter to fix this.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-4-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 23:24:13 -07:00
Ahmad Fatoum
bbf0ec4f57 reboot: reboot, not shutdown, on hw_protection_reboot timeout
hw_protection_shutdown() will kick off an orderly shutdown and if that
takes longer than a configurable amount of time, an emergency shutdown
will occur.

Recently, hw_protection_reboot() was added for those systems that don't
implement a proper shutdown and are better served by rebooting and having
the boot firmware worry about doing something about the critical
condition.

On timeout of the orderly reboot of hw_protection_reboot(), the system
would go into shutdown, instead of reboot.  This is not a good idea, as
going into shutdown was explicitly not asked for.

Fix this by always doing an emergency reboot if hw_protection_reboot() is
called and the orderly reboot takes too long.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-2-e1c09b090c0c@pengutronix.de
Fixes: 79fa723ba8 ("reboot: Introduce thermal_zone_device_critical_reboot()")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: Benson Leung <bleung@chromium.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring (Arm) <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 23:24:13 -07:00
Ahmad Fatoum
318f05a057 reboot: replace __hw_protection_shutdown bool action parameter with an enum
Patch series "reboot: support runtime configuration of emergency
hw_protection action", v3.

We currently leave the decision of whether to shutdown or reboot to
protect hardware in an emergency situation to the individual drivers.

This works out in some cases, where the driver detecting the critical
failure has inside knowledge: It binds to the system management controller
for example or is guided by hardware description that defines what to do.

This is inadequate in the general case though as a driver reporting e.g. 
an imminent power failure can't know whether a shutdown or a reboot would
be more appropriate for a given hardware platform.

To address this, this series adds a hw_protection kernel parameter and
sysfs toggle that can be used to change the action from the shutdown
default to reboot.  A new hw_protection_trigger API then makes use of this
default action.

My particular use case is unattended embedded systems that don't have
support for shutdown and that power on automatically when power is
supplied:

  - A brief power cycle gets detected by the driver
  - The kernel powers down the system and SoC goes into shutdown mode
  - Power is restored
  - The system remains oblivious to the restored power
  - System needs to be manually power cycled for a duration long enough
    to drain the capacitors

With this series, such systems can configure the kernel with
hw_protection=reboot to have the boot firmware worry about critical
conditions.


This patch (of 12):

Currently __hw_protection_shutdown() either reboots or shuts down the
system according to its shutdown argument.

To make the logic easier to follow, both inside __hw_protection_shutdown
and at caller sites, lets replace the bool parameter with an enum.

This will be extra useful, when in a later commit, a third action is added
to the enumeration.

No functional change.

Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-0-e1c09b090c0c@pengutronix.de
Link: https://lkml.kernel.org/r/20250217-hw_protection-reboot-v3-1-e1c09b090c0c@pengutronix.de
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Cc: Benson Leung <bleung@chromium.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Matteo Croce <teknoraver@meta.com>
Cc: Matti Vaittinen <mazziesaccount@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 23:24:13 -07:00
Sebastian Andrzej Siewior
b4dc0bee2a ucount: use rcuref_t for reference counting
Use rcuref_t for reference counting.  This eliminates the cmpxchg loop in
the get and put path.  This also eliminates the need to acquire the lock
in the put path because once the final user returns the reference, it can
no longer be obtained anymore.

Use rcuref_t for reference counting.

Link: https://lkml.kernel.org/r/20250203150525.456525-5-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mengen Sun <mengensun@tencent.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: YueHong Wu <yuehongwu@tencent.com>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:50 -07:00
Sebastian Andrzej Siewior
5f01a22c5b ucount: use RCU for ucounts lookups
The ucounts element is looked up under ucounts_lock.  This can be
optimized by using RCU for a lockless lookup and return and element if the
reference can be obtained.

Replace hlist_head with hlist_nulls_head which is RCU compatible.  Let
find_ucounts() search for the required item within a RCU section and
return the item if a reference could be obtained.  This means
alloc_ucounts() will always return an element (unless the memory
allocation failed).  Let put_ucounts() RCU free the element if the
reference counter dropped to zero.

Link: https://lkml.kernel.org/r/20250203150525.456525-4-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mengen Sun <mengensun@tencent.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: YueHong Wu <yuehongwu@tencent.com>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:50 -07:00
Sebastian Andrzej Siewior
328152e677 ucount: replace get_ucounts_or_wrap() with atomic_inc_not_zero()
get_ucounts_or_wrap() increments the counter and if the counter is
negative then it decrements it again in order to reset the previous
increment.  This statement can be replaced with atomic_inc_not_zero() to
only increment the counter if it is not yet 0.

This simplifies the get function because the put (if the get failed) can
be removed.  atomic_inc_not_zero() is implement as a cmpxchg() loop which
can be repeated several times if another get/put is performed in parallel.
This will be optimized later.

Increment the reference counter only if not yet dropped to zero.

Link: https://lkml.kernel.org/r/20250203150525.456525-3-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mengen Sun <mengensun@tencent.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: YueHong Wu <yuehongwu@tencent.com>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:50 -07:00
Sourabh Jain
9f0552c978 crash: let arch decide usable memory range in reserved area
Although the crashkernel area is reserved, on architectures like PowerPC,
it is possible for the crashkernel reserved area to contain components
like RTAS, TCE, OPAL, etc.  To avoid placing kexec segments over these
components, PowerPC has its own set of APIs to locate holes in the
crashkernel reserved area.

Add an arch hook in the generic locate mem hole APIs so that architectures
can handle such special regions in the crashkernel area while locating
memory holes for kexec segments using generic APIs.  With this, a lot of
redundant arch-specific code can be removed, as it performs the exact same
job as the generic APIs.

To keep the generic and arch-specific changes separate, the changes
related to moving PowerPC to use the generic APIs and the removal of
PowerPC-specific APIs for memory hole allocation are done in a subsequent
patch titled "powerpc/crash: Use generic APIs to locate memory hole for
kdump.

Link: https://lkml.kernel.org/r/20250131113830.925179-4-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:47 -07:00
Sourabh Jain
7b54a96f30 crash: remove an unused argument from reserve_crashkernel_generic()
cmdline argument is not used in reserve_crashkernel_generic() so remove
it.  Correspondingly, all the callers have been updated as well.

No functional change intended.

Link: https://lkml.kernel.org/r/20250131113830.925179-3-sourabhjain@linux.ibm.com
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:47 -07:00
Sourabh Jain
9986fb5164 kexec: initialize ELF lowest address to ULONG_MAX
Patch series "powerpc/crash: use generic crashkernel reservation", v3.

Commit 0ab97169aa ("crash_core: add generic function to do reservation")
added a generic function to reserve crashkernel memory.  So let's use the
same function on powerpc and remove the architecture-specific code that
essentially does the same thing.

The generic crashkernel reservation also provides a way to split the
crashkernel reservation into high and low memory reservations, which can
be enabled for powerpc in the future.

Additionally move powerpc to use generic APIs to locate memory hole for
kexec segments while loading kdump kernel.


This patch (of 7):

kexec_elf_load() loads an ELF executable and sets the address of the
lowest PT_LOAD section to the address held by the lowest_load_addr
function argument.

To determine the lowest PT_LOAD address, a local variable lowest_addr
(type unsigned long) is initialized to UINT_MAX.  After loading each
PT_LOAD, its address is compared to lowest_addr.  If a loaded PT_LOAD
address is lower, lowest_addr is updated.  However, setting lowest_addr to
UINT_MAX won't work when the kernel image is loaded above 4G, as the
returned lowest PT_LOAD address would be invalid.  This is resolved by
initializing lowest_addr to ULONG_MAX instead.

This issue was discovered while implementing crashkernel high/low
reservation on the PowerPC architecture.

Link: https://lkml.kernel.org/r/20250131113830.925179-1-sourabhjain@linux.ibm.com
Link: https://lkml.kernel.org/r/20250131113830.925179-2-sourabhjain@linux.ibm.com
Fixes: a0458284f0 ("powerpc: Add support code for kexec_file_load()")
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:47 -07:00
Andrii Nakryiko
0c555a3c1b mm,procfs: allow read-only remote mm access under CAP_PERFMON
It's very common for various tracing and profiling toolis to need to
access /proc/PID/maps contents for stack symbolization needs to learn
which shared libraries are mapped in memory, at which file offset, etc. 
Currently, access to /proc/PID/maps requires CAP_SYS_PTRACE (unless we are
looking at data for our own process, which is a trivial case not too
relevant for profilers use cases).

Unfortunately, CAP_SYS_PTRACE implies way more than just ability to
discover memory layout of another process: it allows to fully control
arbitrary other processes.  This is problematic from security POV for
applications that only need read-only /proc/PID/maps (and other similar
read-only data) access, and in large production settings CAP_SYS_PTRACE is
frowned upon even for the system-wide profilers.

On the other hand, it's already possible to access similar kind of
information (and more) with just CAP_PERFMON capability.  E.g., setting up
PERF_RECORD_MMAP collection through perf_event_open() would give one
similar information to what /proc/PID/maps provides.

CAP_PERFMON, together with CAP_BPF, is already a very common combination
for system-wide profiling and observability application.  As such, it's
reasonable and convenient to be able to access /proc/PID/maps with
CAP_PERFMON capabilities instead of CAP_SYS_PTRACE.

For procfs, these permissions are checked through common mm_access()
helper, and so we augment that with cap_perfmon() check *only* if
requested mode is PTRACE_MODE_READ.  I.e., PTRACE_MODE_ATTACH wouldn't be
permitted by CAP_PERFMON.  So /proc/PID/mem, which uses
PTRACE_MODE_ATTACH, won't be permitted by CAP_PERFMON, but /proc/PID/maps,
/proc/PID/environ, and a bunch of other read-only contents will be
allowable under CAP_PERFMON.

Besides procfs itself, mm_access() is used by process_madvise() and
process_vm_{readv,writev}() syscalls.  The former one uses
PTRACE_MODE_READ to avoid leaking ASLR metadata, and as such CAP_PERFMON
seems like a meaningful allowable capability as well.

process_vm_{readv,writev} currently assume PTRACE_MODE_ATTACH level of
permissions (though for readv PTRACE_MODE_READ seems more reasonable, but
that's outside the scope of this change), and as such won't be affected by
this patch.

Link: https://lkml.kernel.org/r/20250127222114.1132392-1-andrii@kernel.org
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-16 22:30:46 -07:00
Linus Torvalds
1c5183aa6e Miscellaneous scheduler fixes:
- Fix deadline scheduler sysctl parameter setting bug
  - Fix RT scheduler sysctl parameter setting bug
  - Fix possible memory corruption in child_cfs_rq_on_list()
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2025-03-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull misc scheduler fixes from Ingo Molnar:

 - Fix deadline scheduler sysctl parameter setting bug

 - Fix RT scheduler sysctl parameter setting bug

 - Fix possible memory corruption in child_cfs_rq_on_list()

* tag 'sched-urgent-2025-03-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/rt: Update limit of sched_rt sysctl in documentation
  sched/deadline: Use online cpus for validating runtime
  sched/fair: Fix potential memory corruption in child_cfs_rq_on_list
2025-03-07 10:58:54 -10:00
Linus Torvalds
ab60bd5731 Fix a race between PMU registration and event creation,
and fix pmus_lock vs. pmus_srcu lock ordering.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-urgent-2025-03-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf event fixes from Ingo Molnar:
 "Fix a race between PMU registration and event creation, and fix
  pmus_lock vs. pmus_srcu lock ordering"

* tag 'perf-urgent-2025-03-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix perf_pmu_register() vs. perf_init_event()
  perf/core: Fix pmus_lock vs. pmus_srcu ordering
2025-03-07 10:38:33 -10:00
Linus Torvalds
7f0e9ee5e4 vfs-6.14-rc6.fixes
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Merge tag 'vfs-6.14-rc6.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix spelling mistakes in idmappings.rst

 - Fix RCU warnings in override_creds()/revert_creds()

 - Create new pid namespaces with default limit now that pid_max is
   namespaced

* tag 'vfs-6.14-rc6.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  pid: Do not set pid_max in new pid namespaces
  doc: correcting two prefix errors in idmappings.rst
  cred: Fix RCU warnings in override/revert_creds
2025-03-06 08:04:49 -10:00
Shrikanth Hegde
14672f059d sched/deadline: Use online cpus for validating runtime
The ftrace selftest reported a failure because writing -1 to
sched_rt_runtime_us returns -EBUSY. This happens when the possible
CPUs are different from active CPUs.

Active CPUs are part of one root domain, while remaining CPUs are part
of def_root_domain. Since active cpumask is being used, this results in
cpus=0 when a non active CPUs is used in the loop.

Fix it by looping over the online CPUs instead for validating the
bandwidth calculations.

Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lore.kernel.org/r/20250306052954.452005-2-sshegde@linux.ibm.com
2025-03-06 10:21:31 +01:00
Michal Koutný
d385c8bceb
pid: Do not set pid_max in new pid namespaces
It is already difficult for users to troubleshoot which of multiple pid
limits restricts their workload. The per-(hierarchical-)NS pid_max would
contribute to the confusion.
Also, the implementation copies the limit upon creation from
parent, this pattern showed cumbersome with some attributes in legacy
cgroup controllers -- it's subject to race condition between parent's
limit modification and children creation and once copied it must be
changed in the descendant.

Let's do what other places do (ucounts or cgroup limits) -- create new
pid namespaces without any limit at all. The global limit (actually any
ancestor's limit) is still effectively in place, we avoid the
set/unshare race and bumps of global (ancestral) limit have the desired
effect on pid namespace that do not care.

Link: https://lore.kernel.org/r/20240408145819.8787-1-mkoutny@suse.com/
Link: https://lore.kernel.org/r/20250221170249.890014-1-mkoutny@suse.com/
Fixes: 7863dcc72d ("pid: allow pid_max to be set per pid namespace")
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Link: https://lore.kernel.org/r/20250305145849.55491-1-mkoutny@suse.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-03-06 10:18:36 +01:00
Zecheng Li
3b4035ddbf sched/fair: Fix potential memory corruption in child_cfs_rq_on_list
child_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq.
This 'prev' pointer can originate from struct rq's leaf_cfs_rq_list,
making the conversion invalid and potentially leading to memory
corruption. Depending on the relative positions of leaf_cfs_rq_list and
the task group (tg) pointer within the struct, this can cause a memory
fault or access garbage data.

The issue arises in list_add_leaf_cfs_rq, where both
cfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same
leaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list.

This adds a check `if (prev == &rq->leaf_cfs_rq_list)` after the main
conditional in child_cfs_rq_on_list. This ensures that the container_of
operation will convert a correct cfs_rq struct.

This check is sufficient because only cfs_rqs on the same CPU are added
to the list, so verifying the 'prev' pointer against the current rq's list
head is enough.

Fixes a potential memory corruption issue that due to current struct
layout might not be manifesting as a crash but could lead to unpredictable
behavior when the layout changes.

Fixes: fdaba61ef8 ("sched/fair: Ensure that the CFS parent is added after unthrottling")
Signed-off-by: Zecheng Li <zecheng@google.com>
Reviewed-and-tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250304214031.2882646-1-zecheng@google.com
2025-03-05 17:30:54 +01:00
Linus Torvalds
26edad06d5 Probes fixes for v6.14-rc4:
- probe-events: Some issues are fixed.
  . probe-events: Remove unused MAX_ARG_BUF_LEN macro.
    MAX_ARG_BUF_LEN is not used so remove it.
  . fprobe-events: Log error for exceeding the number of entry args.
    Since the max number of entry args is limited, it should be checked
    and rejected when the parser detects it.
  . tprobe-events: Reject invalid tracepoint name
    User can specify an invalid tracepoint name e.g. including '/', then
    the new event is not defined correctly in the eventfs.
  . tprobe-events: Fix a memory leak when tprobe defined with $retval
    There is a memory leak if tprobe is defined with $retval.
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Merge tag 'probes-fixes-v6.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probe events fixes from Masami Hiramatsu:

 - probe-events: Remove unused MAX_ARG_BUF_LEN macro - it is not used

 - fprobe-events: Log error for exceeding the number of entry args.

   Since the max number of entry args is limited, it should be checked
   and rejected when the parser detects it.

 - tprobe-events: Reject invalid tracepoint name

   If a user specifies an invalid tracepoint name (e.g. including '/')
   then the new event is not defined correctly in the eventfs.

 - tprobe-events: Fix a memory leak when tprobe defined with $retval

   There is a memory leak if tprobe is defined with $retval.

* tag 'probes-fixes-v6.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: probe-events: Remove unused MAX_ARG_BUF_LEN macro
  tracing: fprobe-events: Log error for exceeding the number of entry args
  tracing: tprobe-events: Reject invalid tracepoint name
  tracing: tprobe-events: Fix a memory leak when tprobe with $retval
2025-03-03 07:28:15 -10:00
Masami Hiramatsu (Google)
fd5ba38390 tracing: probe-events: Remove unused MAX_ARG_BUF_LEN macro
Commit 18b1e870a4 ("tracing/probes: Add $arg* meta argument for all
function args") introduced MAX_ARG_BUF_LEN but it is not used.
Remove it.

Link: https://lore.kernel.org/all/174055075876.4079315.8805416872155957588.stgit@mhiramat.tok.corp.google.com/

Fixes: 18b1e870a4 ("tracing/probes: Add $arg* meta argument for all function args")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-03-03 11:17:54 +09:00
Peter Zijlstra
003659fec9 perf/core: Fix perf_pmu_register() vs. perf_init_event()
There is a fairly obvious race between perf_init_event() doing
idr_find() and perf_pmu_register() doing idr_alloc() with an
incompletely initialized PMU pointer.

Avoid by doing idr_alloc() on a NULL pointer to register the id, and
swizzling the real struct pmu pointer at the end using idr_replace().

Also making sure to not set struct pmu members after publishing
the struct pmu, duh.

[ introduce idr_cmpxchg() in order to better handle the idr_replace()
  error case -- if it were to return an unexpected pointer, it will
  already have replaced the value and there is no going back. ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241104135517.858805880@infradead.org
2025-03-01 19:38:42 +01:00
Peter Zijlstra
2565e42539 perf/core: Fix pmus_lock vs. pmus_srcu ordering
Commit a63fbed776 ("perf/tracing/cpuhotplug: Fix locking order")
placed pmus_lock inside pmus_srcu, this makes perf_pmu_unregister()
trip lockdep.

Move the locking about such that only pmu_idr and pmus (list) are
modified while holding pmus_lock. This avoids doing synchronize_srcu()
while holding pmus_lock and all is well again.

Fixes: a63fbed776 ("perf/tracing/cpuhotplug: Fix locking order")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241104135517.679556858@infradead.org
2025-03-01 19:38:42 +01:00
Linus Torvalds
209cd6f2ca ARM:
* Fix TCR_EL2 configuration to not use the ASID in TTBR1_EL2
   and not mess-up T1SZ/PS by using the HCR_EL2.E2H==0 layout.
 
 * Bring back the VMID allocation to the vcpu_load phase, ensuring
   that we only setup VTTBR_EL2 once on VHE. This cures an ugly
   race that would lead to running with an unallocated VMID.
 
 RISC-V:
 
 * Fix hart status check in SBI HSM extension
 
 * Fix hart suspend_type usage in SBI HSM extension
 
 * Fix error returned by SBI IPI and TIME extensions for
   unsupported function IDs
 
 * Fix suspend_type usage in SBI SUSP extension
 
 * Remove unnecessary vcpu kick after injecting interrupt
   via IMSIC guest file
 
 x86:
 
 * Fix an nVMX bug where KVM fails to detect that, after nested
   VM-Exit, L1 has a pending IRQ (or NMI).
 
 * To avoid freeing the PIC while vCPUs are still around, which
   would cause a NULL pointer access with the previous patch,
   destroy vCPUs before any VM-level destruction.
 
 * Handle failures to create vhost_tasks
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "ARM:

   - Fix TCR_EL2 configuration to not use the ASID in TTBR1_EL2 and not
     mess-up T1SZ/PS by using the HCR_EL2.E2H==0 layout.

   - Bring back the VMID allocation to the vcpu_load phase, ensuring
     that we only setup VTTBR_EL2 once on VHE. This cures an ugly race
     that would lead to running with an unallocated VMID.

  RISC-V:

   - Fix hart status check in SBI HSM extension

   - Fix hart suspend_type usage in SBI HSM extension

   - Fix error returned by SBI IPI and TIME extensions for unsupported
     function IDs

   - Fix suspend_type usage in SBI SUSP extension

   - Remove unnecessary vcpu kick after injecting interrupt via IMSIC
     guest file

  x86:

   - Fix an nVMX bug where KVM fails to detect that, after nested
     VM-Exit, L1 has a pending IRQ (or NMI).

   - To avoid freeing the PIC while vCPUs are still around, which would
     cause a NULL pointer access with the previous patch, destroy vCPUs
     before any VM-level destruction.

   - Handle failures to create vhost_tasks"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: retry nx_huge_page_recovery_thread creation
  vhost: return task creation error instead of NULL
  KVM: nVMX: Process events on nested VM-Exit if injectable IRQ or NMI is pending
  KVM: x86: Free vCPUs before freeing VM state
  riscv: KVM: Remove unnecessary vcpu kick
  KVM: arm64: Ensure a VMID is allocated before programming VTTBR_EL2
  KVM: arm64: Fix tcr_el2 initialisation in hVHE mode
  riscv: KVM: Fix SBI sleep_type use
  riscv: KVM: Fix SBI TIME error generation
  riscv: KVM: Fix SBI IPI error generation
  riscv: KVM: Fix hart suspend_type use
  riscv: KVM: Fix hart suspend status check
2025-03-01 08:48:53 -08:00
Keith Busch
cb380909ae vhost: return task creation error instead of NULL
Lets callers distinguish why the vhost task creation failed. No one
currently cares why it failed, so no real runtime change from this
patch, but that will not be the case for long.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Message-ID: <20250227230631.303431-2-kbusch@meta.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2025-03-01 02:52:52 -05:00
Linus Torvalds
d203484f25 Prevent cond_resched() based preemption when interrupts are disabled,
on PREEMPT_NONE and PREEMPT_VOLUNTARY kernels.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fix from Ingo Molnar:
 "Prevent cond_resched() based preemption when interrupts are disabled,
  on PREEMPT_NONE and PREEMPT_VOLUNTARY kernels"

* tag 'sched-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/core: Prevent rescheduling when interrupts are disabled
2025-02-28 17:00:16 -08:00
Linus Torvalds
766331f286 Miscellaneous perf events fixes and a minor HW enablement change:
- Fix missing RCU protection in perf_iterate_ctx()
 
  - Fix pmu_ctx_list ordering bug
 
  - Reject the zero page in uprobes
 
  - Fix a family of bugs related to low frequency sampling
 
  - Add Intel Arrow Lake U CPUs to the generic Arrow Lake
    RAPL support table
 
  - Fix a lockdep-assert false positive in uretprobes
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf event fixes from Ingo Molnar:
 "Miscellaneous perf events fixes and a minor HW enablement change:

   - Fix missing RCU protection in perf_iterate_ctx()

   - Fix pmu_ctx_list ordering bug

   - Reject the zero page in uprobes

   - Fix a family of bugs related to low frequency sampling

   - Add Intel Arrow Lake U CPUs to the generic Arrow Lake RAPL support
     table

   - Fix a lockdep-assert false positive in uretprobes"

* tag 'perf-urgent-2025-02-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  uprobes: Remove too strict lockdep_assert() condition in hprobe_expire()
  perf/x86/rapl: Add support for Intel Arrow Lake U
  perf/x86/intel: Use better start period for frequency mode
  perf/core: Fix low freq setting via IOC_PERIOD
  perf/x86: Fix low freqency setting issue
  uprobes: Reject the shared zeropage in uprobe_write_opcode()
  perf/core: Order the PMU list to fix warning about unordered pmu_ctx_list
  perf/core: Add RCU read lock protection to perf_iterate_ctx()
2025-02-28 16:52:10 -08:00
Linus Torvalds
5c44ddaf7d Tracing fixes for v6.14:
- Fix crash from bad histogram entry
 
   An error path in the histogram creation could leave an entry
   in a link list that gets freed. Then when a new entry is added
   it can cause a u-a-f bug. This is fixed by restructuring the code
   so that the histogram is consistent on failure and everything is
   cleaned up appropriately.
 
 - Fix fprobe self test
 
   The fprobe self test relies on no function being attached by ftrace.
   BPF programs can attach to functions via ftrace and systemd now
   does so. This causes those functions to appear in the enabled_functions
   list which holds all functions attached by ftrace. The selftest also
   uses that file to see if functions are being connected correctly.
   It counts the functions in the file, but if there's already functions
   in the file, it fails. Instead, add the number of functions in the file
   at the start of the test to all the calculations during the test.
 
 - Fix potential division by zero of the function profiler stddev
 
   The calculated divisor that calculates the standard deviation of
   the function times can overflow. If the overflow happens to land
   on zero, that can cause a division by zero. Check for zero from
   the calculation before doing the division.
 
   TODO: Catch when it ever overflows and report it accordingly.
         For now, just prevent the system from crashing.
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Merge tag 'trace-v6.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix crash from bad histogram entry

   An error path in the histogram creation could leave an entry in a
   link list that gets freed. Then when a new entry is added it can
   cause a u-a-f bug. This is fixed by restructuring the code so that
   the histogram is consistent on failure and everything is cleaned up
   appropriately.

 - Fix fprobe self test

   The fprobe self test relies on no function being attached by ftrace.
   BPF programs can attach to functions via ftrace and systemd now does
   so. This causes those functions to appear in the enabled_functions
   list which holds all functions attached by ftrace. The selftest also
   uses that file to see if functions are being connected correctly. It
   counts the functions in the file, but if there's already functions in
   the file, it fails. Instead, add the number of functions in the file
   at the start of the test to all the calculations during the test.

 - Fix potential division by zero of the function profiler stddev

   The calculated divisor that calculates the standard deviation of the
   function times can overflow. If the overflow happens to land on zero,
   that can cause a division by zero. Check for zero from the
   calculation before doing the division.

   TODO: Catch when it ever overflows and report it accordingly. For
   now, just prevent the system from crashing.

* tag 'trace-v6.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Avoid potential division by zero in function_stat_show()
  selftests/ftrace: Let fprobe test consider already enabled functions
  tracing: Fix bad hist from corrupting named_triggers list
2025-02-28 15:43:32 -08:00
Nikolay Kuratov
a1a7eb89ca ftrace: Avoid potential division by zero in function_stat_show()
Check whether denominator expression x * (x - 1) * 1000 mod {2^32, 2^64}
produce zero and skip stddev computation in that case.

For now don't care about rec->counter * rec->counter overflow because
rec->time * rec->time overflow will likely happen earlier.

Cc: stable@vger.kernel.org
Cc: Wen Yang <wenyang@linux.alibaba.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250206090156.1561783-1-kniv@yandex-team.ru
Fixes: e31f7939c1 ("ftrace: Avoid potential division by zero in function profiler")
Signed-off-by: Nikolay Kuratov <kniv@yandex-team.ru>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-27 21:02:10 -05:00
Steven Rostedt
6f86bdeab6 tracing: Fix bad hist from corrupting named_triggers list
The following commands causes a crash:

 ~# cd /sys/kernel/tracing/events/rcu/rcu_callback
 ~# echo 'hist:name=bad:keys=common_pid:onmax(bogus).save(common_pid)' > trigger
 bash: echo: write error: Invalid argument
 ~# echo 'hist:name=bad:keys=common_pid' > trigger

Because the following occurs:

event_trigger_write() {
  trigger_process_regex() {
    event_hist_trigger_parse() {

      data = event_trigger_alloc(..);

      event_trigger_register(.., data) {
        cmd_ops->reg(.., data, ..) [hist_register_trigger()] {
          data->ops->init() [event_hist_trigger_init()] {
            save_named_trigger(name, data) {
              list_add(&data->named_list, &named_triggers);
            }
          }
        }
      }

      ret = create_actions(); (return -EINVAL)
      if (ret)
        goto out_unreg;
[..]
      ret = hist_trigger_enable(data, ...) {
        list_add_tail_rcu(&data->list, &file->triggers); <<<---- SKIPPED!!! (this is important!)
[..]
 out_unreg:
      event_hist_unregister(.., data) {
        cmd_ops->unreg(.., data, ..) [hist_unregister_trigger()] {
          list_for_each_entry(iter, &file->triggers, list) {
            if (!hist_trigger_match(data, iter, named_data, false))   <- never matches
                continue;
            [..]
            test = iter;
          }
          if (test && test->ops->free) <<<-- test is NULL

            test->ops->free(test) [event_hist_trigger_free()] {
              [..]
              if (data->name)
                del_named_trigger(data) {
                  list_del(&data->named_list);  <<<<-- NEVER gets removed!
                }
              }
           }
         }

         [..]
         kfree(data); <<<-- frees item but it is still on list

The next time a hist with name is registered, it causes an u-a-f bug and
the kernel can crash.

Move the code around such that if event_trigger_register() succeeds, the
next thing called is hist_trigger_enable() which adds it to the list.

A bunch of actions is called if get_named_trigger_data() returns false.
But that doesn't need to be called after event_trigger_register(), so it
can be moved up, allowing event_trigger_register() to be called just
before hist_trigger_enable() keeping them together and allowing the
file->triggers to be properly populated.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250227163944.1c37f85f@gandalf.local.home
Fixes: 067fe038e7 ("tracing: Add variable reference handling to hist triggers")
Reported-by: Tomas Glozar <tglozar@redhat.com>
Tested-by: Tomas Glozar <tglozar@redhat.com>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Closes: https://lore.kernel.org/all/CAP4=nvTsxjckSBTz=Oe_UYh8keD9_sZC4i++4h72mJLic4_W4A@mail.gmail.com/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-27 21:01:34 -05:00
Thomas Gleixner
82c387ef75 sched/core: Prevent rescheduling when interrupts are disabled
David reported a warning observed while loop testing kexec jump:

  Interrupts enabled after irqrouter_resume+0x0/0x50
  WARNING: CPU: 0 PID: 560 at drivers/base/syscore.c:103 syscore_resume+0x18a/0x220
   kernel_kexec+0xf6/0x180
   __do_sys_reboot+0x206/0x250
   do_syscall_64+0x95/0x180

The corresponding interrupt flag trace:

  hardirqs last  enabled at (15573): [<ffffffffa8281b8e>] __up_console_sem+0x7e/0x90
  hardirqs last disabled at (15580): [<ffffffffa8281b73>] __up_console_sem+0x63/0x90

That means __up_console_sem() was invoked with interrupts enabled. Further
instrumentation revealed that in the interrupt disabled section of kexec
jump one of the syscore_suspend() callbacks woke up a task, which set the
NEED_RESCHED flag. A later callback in the resume path invoked
cond_resched() which in turn led to the invocation of the scheduler:

  __cond_resched+0x21/0x60
  down_timeout+0x18/0x60
  acpi_os_wait_semaphore+0x4c/0x80
  acpi_ut_acquire_mutex+0x3d/0x100
  acpi_ns_get_node+0x27/0x60
  acpi_ns_evaluate+0x1cb/0x2d0
  acpi_rs_set_srs_method_data+0x156/0x190
  acpi_pci_link_set+0x11c/0x290
  irqrouter_resume+0x54/0x60
  syscore_resume+0x6a/0x200
  kernel_kexec+0x145/0x1c0
  __do_sys_reboot+0xeb/0x240
  do_syscall_64+0x95/0x180

This is a long standing problem, which probably got more visible with
the recent printk changes. Something does a task wakeup and the
scheduler sets the NEED_RESCHED flag. cond_resched() sees it set and
invokes schedule() from a completely bogus context. The scheduler
enables interrupts after context switching, which causes the above
warning at the end.

Quite some of the code paths in syscore_suspend()/resume() can result in
triggering a wakeup with the exactly same consequences. They might not
have done so yet, but as they share a lot of code with normal operations
it's just a question of time.

The problem only affects the PREEMPT_NONE and PREEMPT_VOLUNTARY scheduling
models. Full preemption is not affected as cond_resched() is disabled and
the preemption check preemptible() takes the interrupt disabled flag into
account.

Cure the problem by adding a corresponding check into cond_resched().

Reported-by: David Woodhouse <dwmw@amazon.co.uk>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/all/7717fe2ac0ce5f0a2c43fdab8b11f4483d54a2a4.camel@infradead.org
2025-02-27 21:13:57 +01:00
Masami Hiramatsu (Google)
db5e228611 tracing: fprobe-events: Log error for exceeding the number of entry args
Add error message when the number of entry argument exceeds the
maximum size of entry data.
This is currently checked when registering fprobe, but in this case
no error message is shown in the error_log file.

Link: https://lore.kernel.org/all/174055074269.4079315.17809232650360988538.stgit@mhiramat.tok.corp.google.com/

Fixes: 25f00e40ce ("tracing/probes: Support $argN in return probe (kprobe and fprobe)")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-27 09:11:51 +09:00
Masami Hiramatsu (Google)
d0453655b6 tracing: tprobe-events: Reject invalid tracepoint name
Commit 57a7e6de9e ("tracing/fprobe: Support raw tracepoints on
future loaded modules") allows user to set a tprobe on non-exist
tracepoint but it does not check the tracepoint name is acceptable.
So it leads tprobe has a wrong character for events (e.g. with
subsystem prefix). In this case, the event is not shown in the
events directory.

Reject such invalid tracepoint name.

The tracepoint name must consist of alphabet or digit or '_'.

Link: https://lore.kernel.org/all/174055073461.4079315.15875502830565214255.stgit@mhiramat.tok.corp.google.com/

Fixes: 57a7e6de9e ("tracing/fprobe: Support raw tracepoints on future loaded modules")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: stable@vger.kernel.org
2025-02-27 09:10:58 +09:00
Masami Hiramatsu (Google)
ac965d7d88 tracing: tprobe-events: Fix a memory leak when tprobe with $retval
Fix a memory leak when a tprobe is defined with $retval. This
combination is not allowed, but the parse_symbol_and_return() does
not free the *symbol which should not be used if it returns the error.
Thus, it leaks the *symbol memory in that error path.

Link: https://lore.kernel.org/all/174055072650.4079315.3063014346697447838.stgit@mhiramat.tok.corp.google.com/

Fixes: ce51e6153f ("tracing: fprobe-event: Fix to check tracepoint event and return")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: stable@vger.kernel.org
2025-02-27 09:10:21 +09:00
Linus Torvalds
f4ce1f3318 workqueue: An update for v6.14-rc4
This contains a patch improve debug visibility. While it isn't a fix, the
 change carries virtually no risk and makes it substantially easier to chase
 down a class of problems.
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Merge tag 'wq-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue update from Tejun Heo:
 "This contains a patch improve debug visibility.

  While it isn't a fix, the change carries virtually no risk and makes
  it substantially easier to chase down a class of problems"

* tag 'wq-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Log additional details when rejecting work
2025-02-26 14:22:47 -08:00
Linus Torvalds
e6d3c4e535 sched_ext: A fix for v6.14-rc4
pick_task_scx() has a workaround to avoid stalling when the fair class's
 balance() says yes but pick_task() says no. The workaround was incorrectly
 deciding to keep the prev taks running if the task is on SCX even when the
 task is in a sleeping state, which can lead to several confusing failure
 modes. Fix it by testing the prev task is currently queued on SCX instead.
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Merge tag 'sched_ext-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext fix from Tejun Heo:
 "pick_task_scx() has a workaround to avoid stalling when the fair
  class's balance() says yes but pick_task() says no.

  The workaround was incorrectly deciding to keep the prev taks running
  if the task is on SCX even when the task is in a sleeping state, which
  can lead to several confusing failure modes.

  Fix it by testing the prev task is currently queued on SCX instead"

* tag 'sched_ext-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  sched_ext: Fix pick_task_scx() picking non-queued tasks when it's called without balance()
2025-02-26 14:13:11 -08:00
Andrii Nakryiko
f8c857238a uprobes: Remove too strict lockdep_assert() condition in hprobe_expire()
hprobe_expire() is used to atomically switch pending uretprobe instance
(struct return_instance) from being SRCU protected to be refcounted.
This can be done from background timer thread, or synchronously within
current thread when task is forked.

In the former case, return_instance has to be protected through RCU read
lock, and that's what hprobe_expire() used to check with
lockdep_assert(rcu_read_lock_held()).

But in the latter case (hprobe_expire() called from dup_utask()) there
is no RCU lock being held, and it's both unnecessary and incovenient.
Inconvenient due to the intervening memory allocations inside
dup_return_instance()'s loop. Unnecessary because dup_utask() is called
synchronously in current thread, and no uretprobe can run at that point,
so return_instance can't be freed either.

So drop rcu_read_lock_held() condition, and expand corresponding comment
to explain necessary lifetime guarantees. lockdep_assert()-detected
issue is a false positive.

Fixes: dd1a756778 ("uprobes: SRCU-protect uretprobe lifetime (with timeout)")
Reported-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250225223214.2970740-1-andrii@kernel.org
2025-02-25 23:36:19 +01:00
Tejun Heo
8fef0a3b17 sched_ext: Fix pick_task_scx() picking non-queued tasks when it's called without balance()
a6250aa251 ("sched_ext: Handle cases where pick_task_scx() is called
without preceding balance_scx()") added a workaround to handle the cases
where pick_task_scx() is called without prececing balance_scx() which is due
to a fair class bug where pick_taks_fair() may return NULL after a true
return from balance_fair().

The workaround detects when pick_task_scx() is called without preceding
balance_scx() and emulates SCX_RQ_BAL_KEEP and triggers kicking to avoid
stalling. Unfortunately, the workaround code was testing whether @prev was
on SCX to decide whether to keep the task running. This is incorrect as the
task may be on SCX but no longer runnable.

This could lead to a non-runnable task to be returned from pick_task_scx()
which cause interesting confusions and failures. e.g. A common failure mode
is the task ending up with (!on_rq && on_cpu) state which can cause
potential wakers to busy loop, which can easily lead to deadlocks.

Fix it by testing whether @prev has SCX_TASK_QUEUED set. This makes
@prev_on_scx only used in one place. Open code the usage and improve the
comment while at it.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Pat Cody <patcody@meta.com>
Fixes: a6250aa251 ("sched_ext: Handle cases where pick_task_scx() is called without preceding balance_scx()")
Cc: stable@vger.kernel.org # v6.12+
Acked-by: Andrea Righi <arighi@nvidia.com>
2025-02-25 08:28:52 -10:00
Kan Liang
0d39844150 perf/core: Fix low freq setting via IOC_PERIOD
A low attr::freq value cannot be set via IOC_PERIOD on some platforms.

The perf_event_check_period() introduced in:

  81ec3f3c4c ("perf/x86: Add check_period PMU callback")

was intended to check the period, rather than the frequency.
A low frequency may be mistakenly rejected by limit_period().

Fix it.

Fixes: 81ec3f3c4c ("perf/x86: Add check_period PMU callback")
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250117151913.3043942-2-kan.liang@linux.intel.com
Closes: https://lore.kernel.org/lkml/20250115154949.3147-1-ravi.bangoria@amd.com/
2025-02-25 14:54:14 +01:00
Tong Tiangen
bddf10d26e uprobes: Reject the shared zeropage in uprobe_write_opcode()
We triggered the following crash in syzkaller tests:

  BUG: Bad page state in process syz.7.38  pfn:1eff3
  page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1eff3
  flags: 0x3fffff00004004(referenced|reserved|node=0|zone=1|lastcpupid=0x1fffff)
  raw: 003fffff00004004 ffffe6c6c07bfcc8 ffffe6c6c07bfcc8 0000000000000000
  raw: 0000000000000000 0000000000000000 00000000fffffffe 0000000000000000
  page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
  Call Trace:
   <TASK>
   dump_stack_lvl+0x32/0x50
   bad_page+0x69/0xf0
   free_unref_page_prepare+0x401/0x500
   free_unref_page+0x6d/0x1b0
   uprobe_write_opcode+0x460/0x8e0
   install_breakpoint.part.0+0x51/0x80
   register_for_each_vma+0x1d9/0x2b0
   __uprobe_register+0x245/0x300
   bpf_uprobe_multi_link_attach+0x29b/0x4f0
   link_create+0x1e2/0x280
   __sys_bpf+0x75f/0xac0
   __x64_sys_bpf+0x1a/0x30
   do_syscall_64+0x56/0x100
   entry_SYSCALL_64_after_hwframe+0x78/0xe2

   BUG: Bad rss-counter state mm:00000000452453e0 type:MM_FILEPAGES val:-1

The following syzkaller test case can be used to reproduce:

  r2 = creat(&(0x7f0000000000)='./file0\x00', 0x8)
  write$nbd(r2, &(0x7f0000000580)=ANY=[], 0x10)
  r4 = openat(0xffffffffffffff9c, &(0x7f0000000040)='./file0\x00', 0x42, 0x0)
  mmap$IORING_OFF_SQ_RING(&(0x7f0000ffd000/0x3000)=nil, 0x3000, 0x0, 0x12, r4, 0x0)
  r5 = userfaultfd(0x80801)
  ioctl$UFFDIO_API(r5, 0xc018aa3f, &(0x7f0000000040)={0xaa, 0x20})
  r6 = userfaultfd(0x80801)
  ioctl$UFFDIO_API(r6, 0xc018aa3f, &(0x7f0000000140))
  ioctl$UFFDIO_REGISTER(r6, 0xc020aa00, &(0x7f0000000100)={{&(0x7f0000ffc000/0x4000)=nil, 0x4000}, 0x2})
  ioctl$UFFDIO_ZEROPAGE(r5, 0xc020aa04, &(0x7f0000000000)={{&(0x7f0000ffd000/0x1000)=nil, 0x1000}})
  r7 = bpf$PROG_LOAD(0x5, &(0x7f0000000140)={0x2, 0x3, &(0x7f0000000200)=ANY=[@ANYBLOB="1800000000120000000000000000000095"], &(0x7f0000000000)='GPL\x00', 0x7, 0x0, 0x0, 0x0, 0x0, '\x00', 0x0, @fallback=0x30, 0xffffffffffffffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x10, 0x0, @void, @value}, 0x94)
  bpf$BPF_LINK_CREATE_XDP(0x1c, &(0x7f0000000040)={r7, 0x0, 0x30, 0x1e, @val=@uprobe_multi={&(0x7f0000000080)='./file0\x00', &(0x7f0000000100)=[0x2], 0x0, 0x0, 0x1}}, 0x40)

The cause is that zero pfn is set to the PTE without increasing the RSS
count in mfill_atomic_pte_zeropage() and the refcount of zero folio does
not increase accordingly. Then, the operation on the same pfn is performed
in uprobe_write_opcode()->__replace_page() to unconditional decrease the
RSS count and old_folio's refcount.

Therefore, two bugs are introduced:

 1. The RSS count is incorrect, when process exit, the check_mm() report
    error "Bad rss-count".

 2. The reserved folio (zero folio) is freed when folio->refcount is zero,
    then free_pages_prepare->free_page_is_bad() report error
    "Bad page state".

There is more, the following warning could also theoretically be triggered:

  __replace_page()
    -> ...
      -> folio_remove_rmap_pte()
        -> VM_WARN_ON_FOLIO(is_zero_folio(folio), folio)

Considering that uprobe hit on the zero folio is a very rare case, just
reject zero old folio immediately after get_user_page_vma_remote().

[ mingo: Cleaned up the changelog ]

Fixes: 7396fa818d ("uprobes/core: Make background page replacement logic account for rss_stat counters")
Fixes: 2b14449835 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints")
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250224031149.1598949-1-tongtiangen@huawei.com
2025-02-24 20:37:45 +01:00
Luo Gengkun
2016066c66 perf/core: Order the PMU list to fix warning about unordered pmu_ctx_list
Syskaller triggers a warning due to prev_epc->pmu != next_epc->pmu in
perf_event_swap_task_ctx_data(). vmcore shows that two lists have the same
perf_event_pmu_context, but not in the same order.

The problem is that the order of pmu_ctx_list for the parent is impacted by
the time when an event/PMU is added. While the order for a child is
impacted by the event order in the pinned_groups and flexible_groups. So
the order of pmu_ctx_list in the parent and child may be different.

To fix this problem, insert the perf_event_pmu_context to its proper place
after iteration of the pmu_ctx_list.

The follow testcase can trigger above warning:

 # perf record -e cycles --call-graph lbr -- taskset -c 3 ./a.out &
 # perf stat -e cpu-clock,cs -p xxx // xxx is the pid of a.out

 test.c

 void main() {
        int count = 0;
        pid_t pid;

        printf("%d running\n", getpid());
        sleep(30);
        printf("running\n");

        pid = fork();
        if (pid == -1) {
                printf("fork error\n");
                return;
        }
        if (pid == 0) {
                while (1) {
                        count++;
                }
        } else {
                while (1) {
                        count++;
                }
        }
 }

The testcase first opens an LBR event, so it will allocate task_ctx_data,
and then open tracepoint and software events, so the parent context will
have 3 different perf_event_pmu_contexts. On inheritance, child ctx will
insert the perf_event_pmu_context in another order and the warning will
trigger.

[ mingo: Tidied up the changelog. ]

Fixes: bd27568117 ("perf: Rewrite core context handling")
Signed-off-by: Luo Gengkun <luogengkun@huaweicloud.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20250122073356.1824736-1-luogengkun@huaweicloud.com
2025-02-24 19:22:37 +01:00
Breno Leitao
0fe8813baf perf/core: Add RCU read lock protection to perf_iterate_ctx()
The perf_iterate_ctx() function performs RCU list traversal but
currently lacks RCU read lock protection. This causes lockdep warnings
when running perf probe with unshare(1) under CONFIG_PROVE_RCU_LIST=y:

	WARNING: suspicious RCU usage
	kernel/events/core.c:8168 RCU-list traversed in non-reader section!!

	 Call Trace:
	  lockdep_rcu_suspicious
	  ? perf_event_addr_filters_apply
	  perf_iterate_ctx
	  perf_event_exec
	  begin_new_exec
	  ? load_elf_phdrs
	  load_elf_binary
	  ? lock_acquire
	  ? find_held_lock
	  ? bprm_execve
	  bprm_execve
	  do_execveat_common.isra.0
	  __x64_sys_execve
	  do_syscall_64
	  entry_SYSCALL_64_after_hwframe

This protection was previously present but was removed in commit
bd27568117 ("perf: Rewrite core context handling"). Add back the
necessary rcu_read_lock()/rcu_read_unlock() pair around
perf_iterate_ctx() call in perf_event_exec().

[ mingo: Use scoped_guard() as suggested by Peter ]

Fixes: bd27568117 ("perf: Rewrite core context handling")
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250117-fix_perf_rcu-v1-1-13cb9210fc6a@debian.org
2025-02-24 19:17:04 +01:00
Linus Torvalds
8b82c18bf9 Two RSEQ fixes:
- Fix overly spread-out RSEQ concurrency ID allocation pattern that
    regressed certain workloads.
 
  - Fix RSEQ registration syscall behavior on -EFAULT errors when
    CONFIG_DEBUG_RSEQ=y. (This debug option is disabled on most
    distributions.)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-urgent-2025-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull rseq fixes from Ingo Molnar:

 - Fix overly spread-out RSEQ concurrency ID allocation pattern that
   regressed certain workloads

 - Fix RSEQ registration syscall behavior on -EFAULT errors when
   CONFIG_DEBUG_RSEQ=y (This debug option is disabled on most
   distributions)

* tag 'sched-urgent-2025-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq: Fix rseq registration with CONFIG_DEBUG_RSEQ
  sched: Compact RSEQ concurrency IDs with reduced threads and affinity
2025-02-22 09:30:04 -08:00
Linus Torvalds
1ceffff65f Fix x86 Intel Lion Cove CPU event constraints, and fix
uprobes debug/error printk output pointer-value verbosity.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'perf-urgent-2025-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf event fixes from Ingo Molnar:
 "Fix x86 Intel Lion Cove CPU event constraints, and fix uprobes
  debug/error printk output pointer-value verbosity"

* tag 'perf-urgent-2025-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel: Fix event constraints for LNC
  uprobes: Don't use %pK through printk
2025-02-22 09:26:12 -08:00
Linus Torvalds
b8c8c1414f tracing fixes for v6.14:
Function graph accounting fixes:
 
 - Fix the manage ops hashes
 
   The function graph registers a "manager ops" and "sub-ops" to ftrace.
   The manager ops does not have any callback but calls the sub-ops
   callbacks. The manage ops hashes (what is used to tell ftrace what
   functions to attach to) is built on the sub-ops it manages.
 
   There was an error in the way it built the hash. An empty hash means to
   attach to all functions. When the manager ops had one sub-ops it properly
   copied its hash. But when the manager ops had more than one sub-ops, it
   went into a loop to make a set of all functions it needed to add to the
   hash. If any of the subops hashes was empty, that would mean to attach
   to all functions. The error was that the first iteration of the loop
   passed in an empty hash to start with in order to add the other hashes.
   That starting hash was mistaken as to attach to all functions. This made
   the manage ops attach to all functions whenever it had two or more
   sub-ops, even if each sub-op was attached to only a single function.
 
 - Do not add duplicate entries to the manager ops hash
 
   If two or more subops hashes trace the same function, an entry for that
   function will be added to the manager ops for each subops. This causes
   waste and extra overhead.
 
 Fprobe accounting fixes:
 
 - Remove last function from fprobe hash
 
   Fprobes has a ftrace hash to manage which functions an fprobe is attached
   to. It also has a counter of how many fprobes are attached. When the last
   fprobe is removed, it unregisters the fprobe from ftrace but does not
   remove the functions the last fprobe was attached to from the hash. This
   leaves the old functions attached. When a new fprobe is added, the fprobe
   infrastructure attaches to not only the functions of the new fprobe, but
   also to the functions of the last fprobe.
 
 - Fix accounting of the fprobe counter
 
   When a fprobe is added, it updates a counter. If the counter goes from
   zero to one, it attaches its ops to ftrace. When an fprobe is removed, the
   counter is decremented. If the counter goes from 1 to zero, it removes the
   fprobes ops from ftrace. There was an issue where if two fprobes trace the
   same function, the addition of each fprobe would increment the counter.
   But when removing the first of the fprobes, it would notice that another
   fprobe is still attached to one of its functions no it does not remove
   the functions from the ftrace ops. But it also did not decrement the
   counter. When the last fprobe is removed, the counter is still one. This
   leaves the fprobes callback still registered with ftrace and it being
   called by the functions defined by the fprobes ops hash.  Worse yet,
   because all the functions from the fprobe ops hash have been removed, that
   tells ftrace that it wants to trace all functions. Thus, this puts the
   state of the system where every function is calling the fprobe callback
   handler (which does nothing as there are no registered fprobes), but this
   causes a good 13% slow down of the entire system.
 
 Other updates:
 
 - Add a selftest to test the above issues to prevent regressions.
 
 - Fix preempt count accounting in function tracing
 
   Better recursion protection was added to function tracing which added
   another layer of preempt disable. As the preempt_count gets traced in the
   event, it needs to subtract the amount of preempt disabling the tracer
   does to record what the preempt_count was when the trace was triggered.
 
 - Fix memory leak in output of set_event
 
   A variable is passed by the seq_file functions in the location that is
   set by the return of the next() function. The start() function allocates
   it and the stop() function frees it. But when the last item is found, the
   next() returns NULL which leaks the data that was allocated in start().
   The m->private is used for something else, so have next() free the data
   when it returns NULL, as stop() will then just receive NULL in that case.
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Merge tag 'ftrace-v6.14-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Function graph accounting fixes:

   - Fix the manage ops hashes

     The function graph registers a "manager ops" and "sub-ops" to
     ftrace. The manager ops does not have any callback but calls the
     sub-ops callbacks. The manage ops hashes (what is used to tell
     ftrace what functions to attach to) is built on the sub-ops it
     manages.

     There was an error in the way it built the hash. An empty hash
     means to attach to all functions. When the manager ops had one
     sub-ops it properly copied its hash. But when the manager ops had
     more than one sub-ops, it went into a loop to make a set of all
     functions it needed to add to the hash. If any of the subops hashes
     was empty, that would mean to attach to all functions. The error
     was that the first iteration of the loop passed in an empty hash to
     start with in order to add the other hashes. That starting hash was
     mistaken as to attach to all functions. This made the manage ops
     attach to all functions whenever it had two or more sub-ops, even
     if each sub-op was attached to only a single function.

   - Do not add duplicate entries to the manager ops hash

     If two or more subops hashes trace the same function, an entry for
     that function will be added to the manager ops for each subops.
     This causes waste and extra overhead.

  Fprobe accounting fixes:

   - Remove last function from fprobe hash

     Fprobes has a ftrace hash to manage which functions an fprobe is
     attached to. It also has a counter of how many fprobes are
     attached. When the last fprobe is removed, it unregisters the
     fprobe from ftrace but does not remove the functions the last
     fprobe was attached to from the hash. This leaves the old functions
     attached. When a new fprobe is added, the fprobe infrastructure
     attaches to not only the functions of the new fprobe, but also to
     the functions of the last fprobe.

   - Fix accounting of the fprobe counter

     When a fprobe is added, it updates a counter. If the counter goes
     from zero to one, it attaches its ops to ftrace. When an fprobe is
     removed, the counter is decremented. If the counter goes from 1 to
     zero, it removes the fprobes ops from ftrace.

     There was an issue where if two fprobes trace the same function,
     the addition of each fprobe would increment the counter. But when
     removing the first of the fprobes, it would notice that another
     fprobe is still attached to one of its functions no it does not
     remove the functions from the ftrace ops.

     But it also did not decrement the counter, so when the last fprobe
     is removed, the counter is still one. This leaves the fprobes
     callback still registered with ftrace and it being called by the
     functions defined by the fprobes ops hash. Worse yet, because all
     the functions from the fprobe ops hash have been removed, that
     tells ftrace that it wants to trace all functions.

     Thus, this puts the state of the system where every function is
     calling the fprobe callback handler (which does nothing as there
     are no registered fprobes), but this causes a good 13% slow down of
     the entire system.

  Other updates:

   - Add a selftest to test the above issues to prevent regressions.

   - Fix preempt count accounting in function tracing

     Better recursion protection was added to function tracing which
     added another layer of preempt disable. As the preempt_count gets
     traced in the event, it needs to subtract the amount of preempt
     disabling the tracer does to record what the preempt_count was when
     the trace was triggered.

   - Fix memory leak in output of set_event

     A variable is passed by the seq_file functions in the location that
     is set by the return of the next() function. The start() function
     allocates it and the stop() function frees it. But when the last
     item is found, the next() returns NULL which leaks the data that
     was allocated in start(). The m->private is used for something
     else, so have next() free the data when it returns NULL, as stop()
     will then just receive NULL in that case"

* tag 'ftrace-v6.14-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Fix memory leak when reading set_event file
  ftrace: Correct preemption accounting for function tracing.
  selftests/ftrace: Update fprobe test to check enabled_functions file
  fprobe: Fix accounting of when to unregister from function graph
  fprobe: Always unregister fgraph function from ops
  ftrace: Do not add duplicate entries in subops manager ops
  ftrace: Fix accounting of adding subops to a manager ops
2025-02-22 09:03:54 -08:00
Linus Torvalds
3ef7acec97 drm fixes for v6.14-rc4
core:
 - remove MAINTAINERS entry
 
 cgroup/dmem:
 - use correct function for pool descendants
 
 panel:
 - fix signal polarity issue jd9365da-h3
 
 nouveau:
 - folio handling fix
 - config fix
 
 amdxdna:
 - fix missing header
 
 xe:
 - Fix error handling in xe_irq_install
 - Fix devcoredump format
 
 i915:
 - Use spin_lock_irqsave() in interruptible context on guc submission
 - Fixes on DDI and TRANS programming
 - Make sure all planes in use by the joiner have their crtc included
 - Fix 128b/132b modeset issues
 
 msm:
 - More catalog fixes:
 - to skip watchdog programming through top block if its not present
 - fix the setting of WB mask to ensure the WB input control is programmed
   correctly through ping-pong
 - drop lm_pair for sm6150 as that chipset does not have any 3dmerge block
 - Fix the mode validation logic for DP/eDP to account for widebus (2ppc)
   to allow high clock resolutions
 - Fix to disable dither during encoder disable as otherwise this was
   causing kms_writeback failure due to resource sharing between
   WB and DSI paths as DSI uses dither but WB does not
 - Fixes for virtual planes, namely to drop extraneous return and fix
   uninitialized variables
 - Fix to avoid spill-over of DSC encoder block bits when programming
   the bits-per-component
 - Fixes in the DSI PHY to protect against concurrent access of
   PHY_CMN_CLK_CFG regs between clock and display drivers
 - Core/GPU:
 - Fix non-blocking fence wait incorrectly rounding up to 1 jiffy timeout
 - Only print GMU fw version once, instead of each time the GPU resumes
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Merge tag 'drm-fixes-2025-02-22' of https://gitlab.freedesktop.org/drm/kernel

Pull drm fixes from Dave Airlie:
 "Weekly drm fixes pull request, lots of small things all over, msm has
  a bunch of things but all very small, xe, i915, a fix for the cgroup
  dmem controller.

  core:
   - remove MAINTAINERS entry

  cgroup/dmem:
   - use correct function for pool descendants

  panel:
   - fix signal polarity issue jd9365da-h3

  nouveau:
   - folio handling fix
   - config fix

  amdxdna:
   - fix missing header

  xe:
   - Fix error handling in xe_irq_install
   - Fix devcoredump format

  i915:
   - Use spin_lock_irqsave() in interruptible context on guc submission
   - Fixes on DDI and TRANS programming
   - Make sure all planes in use by the joiner have their crtc included
   - Fix 128b/132b modeset issues

  msm:
   - More catalog fixes:
      - to skip watchdog programming through top block if its not
        present
      - fix the setting of WB mask to ensure the WB input control is
        programmed correctly through ping-pong
      - drop lm_pair for sm6150 as that chipset does not have any
        3dmerge block
      - Fix the mode validation logic for DP/eDP to account for widebus
        (2ppc) to allow high clock resolutions
      - Fix to disable dither during encoder disable as otherwise this
        was causing kms_writeback failure due to resource sharing
        between WB and DSI paths as DSI uses dither but WB does not
      - Fixes for virtual planes, namely to drop extraneous return and
        fix uninitialized variables
      - Fix to avoid spill-over of DSC encoder block bits when
        programming the bits-per-component
      - Fixes in the DSI PHY to protect against concurrent access of
        PHY_CMN_CLK_CFG regs between clock and display drivers
   - Core/GPU:
      - Fix non-blocking fence wait incorrectly rounding up to 1 jiffy
        timeout
      - Only print GMU fw version once, instead of each time the GPU
        resumes"

* tag 'drm-fixes-2025-02-22' of https://gitlab.freedesktop.org/drm/kernel: (28 commits)
  drm/i915/dp: Fix disabling the transcoder function in 128b/132b mode
  drm/i915/dp: Fix error handling during 128b/132b link training
  accel/amdxdna: Add missing include linux/slab.h
  MAINTAINERS: Remove myself
  drm/nouveau/pmu: Fix gp10b firmware guard
  cgroup/dmem: Don't open-code css_for_each_descendant_pre
  drm/xe/guc: Fix size_t print format
  drm/xe: Make GUC binaries dump consistent with other binaries in devcoredump
  drm/i915: Make sure all planes in use by the joiner have their crtc included
  drm/i915/ddi: Fix HDMI port width programming in DDI_BUF_CTL
  drm/i915/dsi: Use TRANS_DDI_FUNC_CTL's own port width macro
  drm/xe: Fix error handling in xe_irq_install()
  drm/i915/gt: Use spin_lock_irqsave() in interruptible context
  drm/msm/dsi/phy: Do not overwite PHY_CMN_CLK_CFG1 when choosing bitclk source
  drm/msm/dsi/phy: Protect PHY_CMN_CLK_CFG1 against clock driver
  drm/msm/dsi/phy: Protect PHY_CMN_CLK_CFG0 updated from driver side
  drm/msm/dpu: Drop extraneous return in dpu_crtc_reassign_planes()
  drm/msm/dpu: Don't leak bits_per_component into random DSC_ENC fields
  drm/msm/dpu: Disable dither in phys encoder cleanup
  drm/msm/dpu: Fix uninitialized variable
  ...
2025-02-21 13:10:22 -08:00
Adrian Huang
2fa6a01345 tracing: Fix memory leak when reading set_event file
kmemleak reports the following memory leak after reading set_event file:

  # cat /sys/kernel/tracing/set_event

  # cat /sys/kernel/debug/kmemleak
  unreferenced object 0xff110001234449e0 (size 16):
  comm "cat", pid 13645, jiffies 4294981880
  hex dump (first 16 bytes):
    01 00 00 00 00 00 00 00 a8 71 e7 84 ff ff ff ff  .........q......
  backtrace (crc c43abbc):
    __kmalloc_cache_noprof+0x3ca/0x4b0
    s_start+0x72/0x2d0
    seq_read_iter+0x265/0x1080
    seq_read+0x2c9/0x420
    vfs_read+0x166/0xc30
    ksys_read+0xf4/0x1d0
    do_syscall_64+0x79/0x150
    entry_SYSCALL_64_after_hwframe+0x76/0x7e

The issue can be reproduced regardless of whether set_event is empty or
not. Here is an example about the valid content of set_event.

  # cat /sys/kernel/tracing/set_event
  sched:sched_process_fork
  sched:sched_switch
  sched:sched_wakeup
  *:*:mod:trace_events_sample

The root cause is that s_next() returns NULL when nothing is found.
This results in s_stop() attempting to free a NULL pointer because its
parameter is NULL.

Fix the issue by freeing the memory appropriately when s_next() fails
to find anything.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250220031528.7373-1-ahuang12@lenovo.com
Fixes: b355247df1 ("tracing: Cache ":mod:" events for modules not loaded yet")
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-21 09:36:12 -05:00
Sebastian Andrzej Siewior
57b76bedc5 ftrace: Correct preemption accounting for function tracing.
The function tracer should record the preemption level at the point when
the function is invoked. If the tracing subsystem decrement the
preemption counter it needs to correct this before feeding the data into
the trace buffer. This was broken in the commit cited below while
shifting the preempt-disabled section.

Use tracing_gen_ctx_dec() which properly subtracts one from the
preemption counter on a preemptible kernel.

Cc: stable@vger.kernel.org
Cc: Wander Lairson Costa <wander@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/20250220140749.pfw8qoNZ@linutronix.de
Fixes: ce5e48036c ("ftrace: disable preemption when recursion locked")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-21 09:36:12 -05:00
Steven Rostedt
ca26554a14 fprobe: Fix accounting of when to unregister from function graph
When adding a new fprobe, it will update the function hash to the
functions the fprobe is attached to and register with function graph to
have it call the registered functions. The fprobe_graph_active variable
keeps track of the number of fprobes that are using function graph.

If two fprobes attach to the same function, it increments the
fprobe_graph_active for each of them. But when they are removed, the first
fprobe to be removed will see that the function it is attached to is also
used by another fprobe and it will not remove that function from
function_graph. The logic will skip decrementing the fprobe_graph_active
variable.

This causes the fprobe_graph_active variable to not go to zero when all
fprobes are removed, and in doing so it does not unregister from
function graph. As the fgraph ops hash will now be empty, and an empty
filter hash means all functions are enabled, this triggers function graph
to add a callback to the fprobe infrastructure for every function!

 # echo "f:myevent1 kernel_clone" >> /sys/kernel/tracing/dynamic_events
 # echo "f:myevent2 kernel_clone%return" >> /sys/kernel/tracing/dynamic_events
 # cat /sys/kernel/tracing/enabled_functions
kernel_clone (1)           	tramp: 0xffffffffc0024000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60

 # > /sys/kernel/tracing/dynamic_events
 # cat /sys/kernel/tracing/enabled_functions
trace_initcall_start_cb (1)             tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
run_init_process (1)            tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
try_to_run_init_process (1)             tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
x86_pmu_show_pmu_cap (1)                tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
cleanup_rapl_pmus (1)                   tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
uncore_free_pcibus_map (1)              tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
uncore_types_exit (1)                   tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
uncore_pci_exit.part.0 (1)              tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
kvm_shutdown (1)                tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
vmx_dump_msrs (1)               tramp: 0xffffffffc0026000 (function_trace_call+0x0/0x170) ->function_trace_call+0x0/0x170
[..]

 # cat /sys/kernel/tracing/enabled_functions | wc -l
54702

If a fprobe is being removed and all its functions are also traced by
other fprobes, still decrement the fprobe_graph_active counter.

Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/20250220202055.565129766@goodmis.org
Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Closes: https://lore.kernel.org/all/20250217114918.10397-A-hca@linux.ibm.com/
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-21 09:36:12 -05:00
Steven Rostedt
ded9140622 fprobe: Always unregister fgraph function from ops
When the last fprobe is removed, it calls unregister_ftrace_graph() to
remove the graph_ops from function graph. The issue is when it does so, it
calls return before removing the function from its graph ops via
ftrace_set_filter_ips(). This leaves the last function lingering in the
fprobe's fgraph ops and if a probe is added it also enables that last
function (even though the callback will just drop it, it does add unneeded
overhead to make that call).

  # echo "f:myevent1 kernel_clone" >> /sys/kernel/tracing/dynamic_events
  # cat /sys/kernel/tracing/enabled_functions
kernel_clone (1)           	tramp: 0xffffffffc02f3000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60

  # echo "f:myevent2 schedule_timeout" >> /sys/kernel/tracing/dynamic_events
  # cat /sys/kernel/tracing/enabled_functions
kernel_clone (1)           	tramp: 0xffffffffc02f3000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
schedule_timeout (1)           	tramp: 0xffffffffc02f3000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60

  # > /sys/kernel/tracing/dynamic_events
  # cat /sys/kernel/tracing/enabled_functions

  # echo "f:myevent3 kmem_cache_free" >> /sys/kernel/tracing/dynamic_events
  # cat /sys/kernel/tracing/enabled_functions
kmem_cache_free (1)           	tramp: 0xffffffffc0219000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60
schedule_timeout (1)           	tramp: 0xffffffffc0219000 (ftrace_graph_func+0x0/0x60) ->ftrace_graph_func+0x0/0x60

The above enabled a fprobe on kernel_clone, and then on schedule_timeout.
The content of the enabled_functions shows the functions that have a
callback attached to them. The fprobe attached to those functions
properly. Then the fprobes were cleared, and enabled_functions was empty
after that. But after adding a fprobe on kmem_cache_free, the
enabled_functions shows that the schedule_timeout was attached again. This
is because it was still left in the fprobe ops that is used to tell
function graph what functions it wants callbacks from.

Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/20250220202055.393254452@goodmis.org
Fixes: 4346ba1604 ("fprobe: Rewrite fprobe on function-graph tracer")
Tested-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-02-21 09:36:12 -05:00