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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: 479f854a20 ("mm, page_alloc: defer debugging checks of pages allocated from the PCP")
Link: http://lkml.kernel.org/r/20160530090154.GM2527@techsingularity.net
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Vlastimil Babka 2016-06-03 14:55:52 -07:00 committed by Linus Torvalds
parent 879be4f378
commit 83b9355bf6
1 changed files with 5 additions and 4 deletions
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9
mm/page_alloc.c
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@ -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