Commit 83b9355b authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Linus Torvalds

mm, page_alloc: prevent infinite loop in buffered_rmqueue()

In DEBUG_VM kernel, we can hit infinite loop for order == 0 in
buffered_rmqueue() when check_new_pcp() returns 1, because the bad page
is never removed from the pcp list.  Fix this by removing the page
before retrying.  Also we don't need to check if page is non-NULL,
because we simply grab it from the list which was just tested for being
non-empty.

Fixes: 479f854a ("mm, page_alloc: defer debugging checks of pages allocated from the PCP")
Link: http://lkml.kernel.org/r/20160530090154.GM2527@techsingularity.netSigned-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Reported-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 879be4f3
......@@ -2615,11 +2615,12 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
page = list_last_entry(list, struct page, lru);
else
page = list_first_entry(list, struct page, lru);
} while (page && check_new_pcp(page));
__dec_zone_state(zone, NR_ALLOC_BATCH);
list_del(&page->lru);
pcp->count--;
__dec_zone_state(zone, NR_ALLOC_BATCH);
list_del(&page->lru);
pcp->count--;
} while (check_new_pcp(page));
} else {
/*
* We most definitely don't want callers attempting to
......
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