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| author | Marco Elver <elver@google.com> | 2024-11-22 16:39:47 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-12-14 20:03:32 +0100 |
| commit | 9bfeeeff2c92b9dd261198b601b45bde4c529841 (patch) | |
| tree | 44912a5b55b95349be9b0ce1bd786352106b59b7 /lib/stackdepot.c | |
| parent | eb58460ff77e7bb9333b7e66ca91f1698729606e (diff) | |
| download | linux-9bfeeeff2c92b9dd261198b601b45bde4c529841.tar.gz linux-9bfeeeff2c92b9dd261198b601b45bde4c529841.tar.bz2 linux-9bfeeeff2c92b9dd261198b601b45bde4c529841.zip | |
stackdepot: fix stack_depot_save_flags() in NMI context
commit 031e04bdc834cda3b054ef6b698503b2b97e8186 upstream.
Per documentation, stack_depot_save_flags() was meant to be usable from
NMI context if STACK_DEPOT_FLAG_CAN_ALLOC is unset. However, it still
would try to take the pool_lock in an attempt to save a stack trace in the
current pool (if space is available).
This could result in deadlock if an NMI is handled while pool_lock is
already held. To avoid deadlock, only try to take the lock in NMI context
and give up if unsuccessful.
The documentation is fixed to clearly convey this.
Link: https://lkml.kernel.org/r/Z0CcyfbPqmxJ9uJH@elver.google.com
Link: https://lkml.kernel.org/r/20241122154051.3914732-1-elver@google.com
Fixes: 4434a56ec209 ("stackdepot: make fast paths lock-less again")
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib/stackdepot.c')
| -rw-r--r-- | lib/stackdepot.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/lib/stackdepot.c b/lib/stackdepot.c index 5ed34cc963fc..245d5b416699 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -630,7 +630,15 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries, prealloc = page_address(page); } - raw_spin_lock_irqsave(&pool_lock, flags); + if (in_nmi()) { + /* We can never allocate in NMI context. */ + WARN_ON_ONCE(can_alloc); + /* Best effort; bail if we fail to take the lock. */ + if (!raw_spin_trylock_irqsave(&pool_lock, flags)) + goto exit; + } else { + raw_spin_lock_irqsave(&pool_lock, flags); + } printk_deferred_enter(); /* Try to find again, to avoid concurrently inserting duplicates. */ |