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mm/kmemleak: avoid deadlock by moving pr_warn() outside kmemleak_lock
When netpoll is enabled, calling pr_warn_once() while holding
kmemleak_lock in mem_pool_alloc() can cause a deadlock due to lock
inversion with the netconsole subsystem. This occurs because
pr_warn_once() may trigger netpoll, which eventually leads to
__alloc_skb() and back into kmemleak code, attempting to reacquire
kmemleak_lock.
This is the path for the deadlock.
mem_pool_alloc()
-> raw_spin_lock_irqsave(&kmemleak_lock, flags);
-> pr_warn_once()
-> netconsole subsystem
-> netpoll
-> __alloc_skb
-> __create_object
-> raw_spin_lock_irqsave(&kmemleak_lock, flags);
Fix this by setting a flag and issuing the pr_warn_once() after
kmemleak_lock is released.
Link: https://lkml.kernel.org/r/20250731-kmemleak_lock-v1-1-728fd470198f@debian.org
Fixes: c566586818
("mm: kmemleak: use the memory pool for early allocations")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reported-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
parent
475356fe28
commit
47b0f6d8f0
@ -470,6 +470,7 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
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{
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{
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unsigned long flags;
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unsigned long flags;
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struct kmemleak_object *object;
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struct kmemleak_object *object;
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bool warn = false;
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/* try the slab allocator first */
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/* try the slab allocator first */
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if (object_cache) {
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if (object_cache) {
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@ -488,8 +489,10 @@ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
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else if (mem_pool_free_count)
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else if (mem_pool_free_count)
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object = &mem_pool[--mem_pool_free_count];
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object = &mem_pool[--mem_pool_free_count];
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else
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else
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pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
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warn = true;
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raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
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raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
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if (warn)
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pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
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return object;
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return object;
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}
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}
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