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linux/mm/kasan
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Waiman Long ac7af1f57a kasan: don't call find_vm_area() in a PREEMPT_RT kernel 
The following bug report was found when running a PREEMPT_RT debug kernel.

 BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 140605, name: kunit_try_catch
 preempt_count: 1, expected: 0

 Call trace:
  rt_spin_lock+0x70/0x140
  find_vmap_area+0x84/0x168
  find_vm_area+0x1c/0x50
  print_address_description.constprop.0+0x2a0/0x320
  print_report+0x108/0x1f8
  kasan_report+0x90/0xc8

Since commit e30a0361b8 ("kasan: make report_lock a raw spinlock"),
report_lock was changed to raw_spinlock_t to fix another similar
PREEMPT_RT problem.  That alone isn't enough to cover other corner cases.

print_address_description() is always invoked under the report_lock.  The
context under this lock is always atomic even on PREEMPT_RT. 
find_vm_area() acquires vmap_node::busy.lock which is a spinlock_t,
becoming a sleeping lock on PREEMPT_RT and must not be acquired in atomic
context.

Don't invoke find_vm_area() on PREEMPT_RT and just print the address. 
Non-PREEMPT_RT builds remain unchanged.  Add a DEFINE_WAIT_OVERRIDE_MAP()
macro to tell lockdep that this lock nesting is allowed because the
PREEMPT_RT part (which is invalid) has been taken care of.  This macro was
first introduced in commit 0cce06ba85 ("debugobjects,locking: Annotate
debug_object_fill_pool() wait type violation").

Link: https://lkml.kernel.org/r/20250217204402.60533-1-longman@redhat.com
Fixes: e30a0361b8 ("kasan: make report_lock a raw spinlock")
Signed-off-by: Waiman Long <longman@redhat.com>
Suggested-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mariano Pache <npache@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-02-17 22:40:04 -08:00
..
common.c slub: Introduce CONFIG_SLUB_RCU_DEBUG 2024-08-27 14:12:51 +02:00
generic.c kasan: make kasan_record_aux_stack_noalloc() the default behaviour 2025-01-13 22:40:36 -08:00
hw_tags.c kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags() 2025-01-25 20:22:44 -08:00
init.c mm: define general function pXd_init() 2024-11-11 17:22:27 -08:00
kasan.h kasan: use correct kernel-doc format 2025-01-25 20:22:41 -08:00
kasan_test_c.c mm:kasan: fix sparse warnings: Should it be static? 2025-01-13 22:40:42 -08:00
kasan_test_rust.rs rust: treewide: switch to the kernel Vec type 2024-10-15 23:10:32 +02:00
Makefile kasan: migrate copy_user_test to kunit 2024-11-11 00:26:44 -08:00
quarantine.c kasan: revert eviction of stack traces in generic mode 2024-02-23 17:27:12 -08:00
report.c kasan: don't call find_vm_area() in a PREEMPT_RT kernel 2025-02-17 22:40:04 -08:00
report_generic.c kasan: stop leaking stack trace handles 2024-01-05 10:17:45 -08:00
report_hw_tags.c kasan: use internal prototypes matching gcc-13 builtins 2023-06-09 16:25:19 -07:00
report_sw_tags.c kasan: use internal prototypes matching gcc-13 builtins 2023-06-09 16:25:19 -07:00
report_tags.c kasan: simplify kasan_complete_mode_report_info for tag-based modes 2023-12-29 11:58:47 -08:00
shadow.c mm/vmalloc: combine all TLB flush operations of KASAN shadow virtual address into one operation 2024-11-05 16:56:21 -08:00
sw_tags.c kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags() 2025-01-25 20:22:46 -08:00
tags.c kasan: simplify saving extra info into tracks 2023-12-29 11:58:46 -08:00