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author | Hugh Dickins <hughd@google.com> | 2016-05-19 17:12:35 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-19 19:12:14 -0700 |
commit | ca707239e8a7958ffb1c31737d41cae1a674c938 (patch) | |
tree | 37792a1ea8ed942fe0337ffa03ef9bb34329a881 /include/linux/mm_inline.h | |
parent | 1269019e69a6798db15edea8921f83215ef954d6 (diff) | |
download | linux-stable-ca707239e8a7958ffb1c31737d41cae1a674c938.tar.gz linux-stable-ca707239e8a7958ffb1c31737d41cae1a674c938.tar.bz2 linux-stable-ca707239e8a7958ffb1c31737d41cae1a674c938.zip |
mm: update_lru_size warn and reset bad lru_size
Though debug kernels have a VM_BUG_ON to help protect from misaccounting
lru_size, non-debug kernels are liable to wrap it around: and then the
vast unsigned long size draws page reclaim into a loop of repeatedly
doing nothing on an empty list, without even a cond_resched().
That soft lockup looks confusingly like an over-busy reclaim scenario,
with lots of contention on the lru_lock in shrink_inactive_list(): yet
has a totally different origin.
Help differentiate with a custom warning in
mem_cgroup_update_lru_size(), even in non-debug kernels; and reset the
size to avoid the lockup. But the particular bug which suggested this
change was mine alone, and since fixed.
Make it a WARN_ONCE: the first occurrence is the most informative, a
flurry may follow, yet even when rate-limited little more is learnt.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mm_inline.h')
-rw-r--r-- | include/linux/mm_inline.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 712e8c37a200..d8cea81ab1ac 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -35,8 +35,8 @@ static __always_inline void del_page_from_lru_list(struct page *page, struct lruvec *lruvec, enum lru_list lru) { int nr_pages = hpage_nr_pages(page); - mem_cgroup_update_lru_size(lruvec, lru, -nr_pages); list_del(&page->lru); + mem_cgroup_update_lru_size(lruvec, lru, -nr_pages); __mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, -nr_pages); } |