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mm/kmemleak: stop the task stack scan early when interrupted

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scan_block() already checks scan_should_stop() for every pointer and bails
out of the current block, but the task stack walk cannot tell and keeps
issuing a separate scan_should_stop() between every task.

Return that status from scan_block() and use it as the task stack loop
condition, so the walk stops as soon as a scan is interrupted.

Link: https://lore.kernel.org/20260615-kmemleak-stack-resched-v3-2-acecd7d7fd92@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Qian Cai <cai@lca.pw>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Breno Leitao 2026-06-15 10:49:07 -07:00 committed by Andrew Morton
parent 5d10d4e19e
commit eb11f56eec
1 changed files with 12 additions and 6 deletions
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18
mm/kmemleak.c
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@ -1525,22 +1525,25 @@ static int scan_should_stop(void)
/* /*
* Scan a memory block (exclusive range) for valid pointers and add those * Scan a memory block (exclusive range) for valid pointers and add those
* found to the gray list. * found to the gray list. Return non-zero if the scan was interrupted.
*/ */
static void scan_block(void *_start, void *_end, static int scan_block(void *_start, void *_end,
struct kmemleak_object *scanned) struct kmemleak_object *scanned)
{ {
unsigned long *ptr; unsigned long *ptr;
unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER); unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
unsigned long *end = _end - (BYTES_PER_POINTER - 1); unsigned long *end = _end - (BYTES_PER_POINTER - 1);
unsigned long flags; unsigned long flags;
int stop = 0;
raw_spin_lock_irqsave(&kmemleak_lock, flags); raw_spin_lock_irqsave(&kmemleak_lock, flags);
for (ptr = start; ptr < end; ptr++) { for (ptr = start; ptr < end; ptr++) {
unsigned long pointer; unsigned long pointer;
if (scan_should_stop()) if (scan_should_stop()) {
stop = 1;
break; break;
}
kasan_disable_current(); kasan_disable_current();
pointer = *(unsigned long *)kasan_reset_tag((void *)ptr); pointer = *(unsigned long *)kasan_reset_tag((void *)ptr);
@ -1550,6 +1553,8 @@ static void scan_block(void *_start, void *_end,
pointer_update_refs(scanned, pointer, OBJECT_PERCPU); pointer_update_refs(scanned, pointer, OBJECT_PERCPU);
} }
raw_spin_unlock_irqrestore(&kmemleak_lock, flags); raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
return stop;
} }
/* /*
@ -1705,6 +1710,7 @@ static void kmemleak_scan_task_stacks(void)
{ {
struct pid *pid; struct pid *pid;
int nr = 1; int nr = 1;
int stop = 0;
do { do {
struct task_struct *p = NULL; struct task_struct *p = NULL;
@ -1723,13 +1729,13 @@ static void kmemleak_scan_task_stacks(void)
void *stack = try_get_task_stack(p); void *stack = try_get_task_stack(p);
if (stack) { if (stack) {
scan_block(stack, stack + THREAD_SIZE, NULL); stop = scan_block(stack, stack + THREAD_SIZE, NULL);
put_task_stack(p); put_task_stack(p);
} }
put_task_struct(p); put_task_struct(p);
} }
cond_resched(); cond_resched();
} while (pid && !scan_should_stop()); } while (pid && !stop);
} }
/* /*