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mm/kmemleak: move up cond_resched() call in page scanning loop 

Commit bde5f6bc68 ("kmemleak: add scheduling point to kmemleak_scan()")
added a cond_resched() call to the struct page scanning loop to prevent
soft lockup from happening.  However, soft lockup can still happen in that
loop in some corner cases when the pages that satisfy the "!(pfn & 63)"
check are skipped for some reasons.

Fix this corner case by moving up the cond_resched() check so that it will
be called every 64 pages unconditionally.

Link: https://lkml.kernel.org/r/20230825164947.1317981-1-longman@redhat.com
Fixes: bde5f6bc68 ("kmemleak: add scheduling point to kmemleak_scan()")
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Waiman Long 2023-08-25 12:49:47 -04:00 committed by Andrew Morton
parent f945116e4e
commit e68d343d27
1 changed files with 3 additions and 2 deletions
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5
mm/kmemleak.c
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@ -1584,6 +1584,9 @@ static void kmemleak_scan(void)
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
struct page *page = pfn_to_online_page(pfn);
if (!(pfn & 63))
cond_resched();
if (!page)
continue;
@ -1594,8 +1597,6 @@ static void kmemleak_scan(void)
if (page_count(page) == 0)
continue;
scan_block(page, page + 1, NULL);
if (!(pfn & 63))
cond_resched();
}
}
put_online_mems();