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mm/kmemleak: stop the per-cpu and struct page scans early too

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The per-cpu and struct page scan loops have no reschedule-stop check of
their own: once a scan is interrupted they keep calling scan_block() for
every remaining block, which scans nothing useful.

Propagate scan_block()'s interrupted status through scan_large_block() and
break both loops as soon as it is set.

Link: https://lore.kernel.org/20260615-kmemleak-stack-resched-v3-3-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 10:49:08 -07:00 committed by Andrew Morton
parent eb11f56eec
commit cdf95d6b33
1 changed files with 17 additions and 6 deletions
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23
mm/kmemleak.c
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@ -1559,18 +1559,22 @@ static int scan_block(void *_start, void *_end,
/*
* Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
* Return non-zero if the scan was interrupted.
*/
#ifdef CONFIG_SMP
static void scan_large_block(void *start, void *end)
static int scan_large_block(void *start, void *end)
{
void *next;
while (start < end) {
next = min(start + MAX_SCAN_SIZE, end);
scan_block(start, next, NULL);
if (scan_block(start, next, NULL))
return 1;
start = next;
cond_resched();
}
return 0;
}
#endif
@ -1890,9 +1894,11 @@ static void kmemleak_scan(void)
#ifdef CONFIG_SMP
/* per-cpu sections scanning */
for_each_possible_cpu(i)
scan_large_block(__per_cpu_start + per_cpu_offset(i),
__per_cpu_end + per_cpu_offset(i));
for_each_possible_cpu(i) {
if (scan_large_block(__per_cpu_start + per_cpu_offset(i),
__per_cpu_end + per_cpu_offset(i)))
break;
}
#endif
/*
@ -1903,6 +1909,7 @@ static void kmemleak_scan(void)
unsigned long start_pfn = zone->zone_start_pfn;
unsigned long end_pfn = zone_end_pfn(zone);
unsigned long pfn;
int stop = 0;
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
struct page *page = pfn_to_online_page(pfn);
@ -1919,8 +1926,12 @@ static void kmemleak_scan(void)
/* only scan if page is in use */
if (page_count(page) == 0)
continue;
scan_block(page, page + 1, NULL);
stop = scan_block(page, page + 1, NULL);
if (stop)
break;
}
if (stop)
break;
}
put_online_mems();