linux/kernel
Andrea Righi c01adf4097 sched_ext: Add RCU protection to scx_root in DSQ iterator
Using a DSQ iterators from a timer callback can trigger the following
lockdep splat when accessing scx_root:

 =============================
 WARNING: suspicious RCU usage
 6.14.0-virtme #1 Not tainted
 -----------------------------
 kernel/sched/ext.c:6907 suspicious rcu_dereference_check() usage!

 other info that might help us debug this:

 rcu_scheduler_active = 2, debug_locks = 1
 no locks held by swapper/0/0.

 stack backtrace:
 CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.14.0-virtme #1 PREEMPT(full)
 Sched_ext: tickless (enabled+all)
 Call Trace:
 <IRQ>
 dump_stack_lvl+0x6f/0xb0
 lockdep_rcu_suspicious.cold+0x4e/0xa3
 bpf_iter_scx_dsq_new+0xb1/0xd0
 bpf_prog_63f4fd1bccc101e7_dispatch_cpu+0x3e/0x156
 bpf_prog_8320d4217989178c_dispatch_all_cpus+0x153/0x1b6
 bpf_prog_97f847d871513f95_sched_timerfn+0x4c/0x264
 ? hrtimer_run_softirq+0x4f/0xd0
 bpf_timer_cb+0x7a/0x140
 __hrtimer_run_queues+0x1f9/0x3a0
 hrtimer_run_softirq+0x8c/0xd0
 handle_softirqs+0xd3/0x3d0
 __irq_exit_rcu+0x9a/0xc0
 irq_exit_rcu+0xe/0x20
 sysvec_apic_timer_interrupt+0x73/0x80

Add a proper dereference check to explicitly validate RCU-safe access to
scx_root from rcu_read_lock() contexts and also from contexts that hold
rcu_read_lock_bh(), such as timer callbacks.

Fixes: cdf5a6faa8 ("sched_ext: Move dsq_hash into scx_sched")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2025-04-30 12:39:50 -10:00
..
bpf bpf_try_alloc_pages 2025-03-30 13:45:28 -07:00
cgroup Driver core updates for 6.15-rc1 2025-04-01 11:02:03 -07:00
configs - The 6 patch series "Enable strict percpu address space checks" from 2025-04-01 09:29:18 -07:00
debug TTY/Serial driver updates for 6.15-rc1 2025-04-02 18:17:33 -07:00
dma dma-mapping: fix missing clear bdr in check_ram_in_range_map() 2025-03-12 13:41:44 +01:00
entry Objtool changes for v6.15: 2025-03-24 21:18:05 -07:00
events mseal sysmap: uprobe mapping 2025-04-01 15:17:16 -07:00
futex futex: Use a hashmask instead of hashsize 2025-02-26 16:07:59 +01:00
gcov gcov: clang: use correct function param names 2025-01-24 22:47:27 -08:00
irq Revert "Merge tag 'irq-msi-2025-03-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip" 2025-03-28 11:22:54 -07:00
kcsan kcsan: Remove redundant call of kallsyms_lookup_name() 2024-10-14 16:44:56 +02:00
livepatch Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
locking - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
module ring-buffer updates for v6.15 2025-03-31 13:37:22 -07:00
power This update includes the following changes: 2025-03-29 10:01:55 -07:00
printk printk changes for 6.15 2025-03-27 19:22:24 -07:00
rcu RCU fixes for v6.15: 2025-04-02 10:04:48 -07:00
sched sched_ext: Add RCU protection to scx_root in DSQ iterator 2025-04-30 12:39:50 -10:00
time Networking changes for 6.15. 2025-03-26 21:48:21 -07:00
trace Persistent buffer cleanups and simplifications for v6.15: 2025-04-03 16:09:29 -07:00
.gitignore
acct.c acct: block access to kernel internal filesystems 2025-02-12 12:24:16 +01:00
async.c
audit.c audit: Initialize lsmctx to avoid memory allocation error 2025-01-29 20:02:04 -05:00
audit.h audit: change context data from secid to lsm_prop 2024-10-11 14:34:16 -04:00
audit_fsnotify.c
audit_tree.c
audit_watch.c VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry 2025-02-19 14:08:41 +01:00
auditfilter.c audit: fix suffixed '/' filename matching 2024-12-05 19:22:38 -05:00
auditsc.c fs: dedup handling of struct filename init and refcounts bumps 2025-03-18 15:34:27 +01:00
backtracetest.c
bounds.c
capability.c capability: Remove unused has_capability 2025-03-07 22:03:09 -06:00
cfi.c Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
compat.c
configs.c
context_tracking.c context_tracking: Make RCU watch ct_kernel_exit_state() warning 2025-03-04 18:44:29 -08:00
cpu.c hyperv-next for 6.15 2025-03-25 14:47:04 -07:00
cpu_pm.c
crash_core.c crash: Use note name macros 2025-02-10 16:56:58 -08:00
crash_reserve.c crash: remove an unused argument from reserve_crashkernel_generic() 2025-03-16 22:30:47 -07:00
cred.c cred: remove old {override,revert}_creds() helpers 2024-12-02 11:25:09 +01:00
delayacct.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
dma.c
elfcorehdr.c
exec_domain.c
exit.c exit: fix the usage of delay_group_leader->exit_code in do_notify_parent() and pidfs_exit() 2025-03-25 15:56:22 +01:00
exit.h
extable.c
fail_function.c
fork.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
freezer.c sched/fair: Fix external p->on_rq users 2024-10-14 09:14:35 +02:00
gen_kheaders.sh Kbuild updates for v6.14 2025-01-31 12:07:07 -08:00
groups.c
hung_task.c hung_task: show the blocker task if the task is hung on mutex 2025-03-21 22:10:04 -07:00
iomem.c mm/memremap: Pass down MEMREMAP_* flags to arch_memremap_wb() 2025-02-21 15:05:38 +01:00
irq_work.c kasan: make kasan_record_aux_stack_noalloc() the default behaviour 2025-01-13 22:40:36 -08:00
jump_label.c jump_label: Use RCU in all users of __module_text_address(). 2025-03-10 11:54:46 +01:00
kallsyms.c kallsyms: Remove KALLSYMS_ABSOLUTE_PERCPU 2025-02-18 10:16:04 +01:00
kallsyms_internal.h
kallsyms_selftest.c kallsyms: Use kthread_run_on_cpu() 2025-01-02 22:12:12 +01:00
kallsyms_selftest.h
kcmp.c kcmp: improve performance adding an unlikely hint to task comparisons 2025-02-21 10:25:33 +01:00
Kconfig.freezer
Kconfig.hz kernel: Fix "select" wording on HZ_250 description 2025-02-21 09:20:30 +01:00
Kconfig.kexec crash, powerpc: default to CRASH_DUMP=n on PPC_BOOK3S_32 2024-11-14 22:43:48 -08:00
Kconfig.locks
Kconfig.preempt sched: No PREEMPT_RT=y for all{yes,mod}config 2024-11-07 15:25:05 +01:00
kcov.c kcov: mark in_softirq_really() as __always_inline 2024-12-30 17:59:08 -08:00
kexec.c
kexec_core.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
kexec_elf.c kexec: initialize ELF lowest address to ULONG_MAX 2025-03-16 22:30:47 -07:00
kexec_file.c crash: let arch decide usable memory range in reserved area 2025-03-16 22:30:47 -07:00
kexec_internal.h kexec: use atomic_try_cmpxchg_acquire() in kexec_trylock() 2024-09-01 20:43:23 -07:00
kheaders.c kheaders: Simplify attribute through __BIN_ATTR_SIMPLE_RO() 2024-12-24 09:46:49 +01:00
kprobes.c kprobes: Use RCU in all users of __module_text_address(). 2025-03-10 11:54:46 +01:00
ksyms_common.c
ksysfs.c kernel/ksysfs.c: simplify bin_attribute definition 2025-01-07 16:59:15 +01:00
kthread.c kthread: Fix return value on kzalloc() failure in kthread_affine_preferred() 2025-02-04 01:42:27 +01:00
latencytop.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
Makefile tracing: Disable branch profiling in noinstr code 2025-03-22 09:49:26 +01:00
module_signature.c
notifier.c reboot: move reboot_notifier_list to kernel/reboot.c 2024-11-05 17:12:31 -08:00
nsproxy.c fdget(), trivial conversions 2024-11-03 01:28:06 -05:00
padata.c padata: switch padata_find_next() to using cpumask_next_wrap() 2025-02-24 16:37:23 -05:00
panic.c These are objtool fixes and updates by Josh Poimboeuf, centered 2025-04-02 10:30:10 -07:00
params.c params: Annotate struct module_param_attrs with __counted_by() 2025-03-10 11:54:46 +01:00
pid.c kernel-6.15-rc1.tasklist_lock 2025-03-24 13:39:27 -07:00
pid_namespace.c pid: Do not set pid_max in new pid namespaces 2025-03-06 10:18:36 +01:00
pid_sysctl.h treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
profile.c
ptrace.c
range.c
reboot.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
regset.c
relay.c relay: use kasprintf() instead of fixed buffer formatting 2025-03-21 22:10:05 -07:00
resource.c resource: replace open coded variant of DEFINE_RES() 2025-03-21 22:10:05 -07:00
resource_kunit.c resource, kunit: fix user-after-free in resource_test_region_intersects() 2024-10-09 12:47:19 -07:00
rseq.c rseq: Fix segfault on registration when rseq_cs is non-zero 2025-03-06 22:26:49 +01:00
scftorture.c scftorture: Handle NULL argument passed to scf_add_to_free_list(). 2024-11-14 16:09:51 -08:00
scs.c
seccomp.c seccomp: avoid the lock trip seccomp_filter_release in common case 2025-02-24 11:17:10 -08:00
signal.c vfs-6.15-rc1.fixes 2025-04-02 16:05:21 -07:00
smp.c CSD-lock pull request for v6.14 2025-01-28 11:34:03 -08:00
smpboot.c
smpboot.h
softirq.c lockdep: Fix wait context check on softirq for PREEMPT_RT 2025-03-25 10:46:44 +01:00
stackleak.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
stacktrace.c
static_call.c
static_call_inline.c Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
stop_machine.c stop-machine: Add comment for rcu_momentary_eqs() 2025-03-11 10:15:52 -07:00
sys.c Updates for the core time/timer subsystem: 2025-03-25 10:33:23 -07:00
sys_ni.c
sysctl-test.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
sysctl.c s390 updates for 6.15 merge window 2025-03-29 11:59:43 -07:00
task_work.c kasan: make kasan_record_aux_stack_noalloc() the default behaviour 2025-01-13 22:40:36 -08:00
taskstats.c fdget(), more trivial conversions 2024-11-03 01:28:06 -05:00
torture.c torture: Add get_torture_init_jiffies() for test-start time 2025-02-05 07:14:24 -08:00
tracepoint.c tracepoint: Print the function symbol when tracepoint_debug is set 2025-03-21 15:30:10 -04:00
tsacct.c
ucount.c ucount: use rcuref_t for reference counting 2025-03-16 22:30:50 -07:00
uid16.c
uid16.h
umh.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
up.c
user-return-notifier.c
user.c uidgid: make sure we fit into one cacheline 2024-09-12 12:16:09 +02:00
user_namespace.c uidgid: add map_id_range_up() 2025-02-12 12:12:27 +01:00
usermode_driver.c
utsname.c
utsname_sysctl.c treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
vhost_task.c vhost: return task creation error instead of NULL 2025-03-01 02:52:52 -05:00
vmcore_info.c mm: support only one page_type per page 2024-09-03 21:15:43 -07:00
watch_queue.c vfs-6.15-rc1.pipe 2025-03-24 09:52:37 -07:00
watchdog.c A treewide hrtimer timer cleanup 2025-03-25 10:54:15 -07:00
watchdog_buddy.c
watchdog_perf.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
workqueue.c workqueue: An update for v6.14-rc4 2025-02-26 14:22:47 -08:00
workqueue_internal.h