diff options
| author | Hugh Dickins <hughd@google.com> | 2012-01-12 17:19:52 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-12 20:13:09 -0800 |
| commit | 12d27107867fc7216e8faaff0b894b0f162dcf75 (patch) | |
| tree | 8f35d39f7e5d0b0f0ba10a3475e9fa4a2581e509 /mm/memcontrol.c | |
| parent | 0cee34fd72c582b4f8ad8ce00645b75fb4168199 (diff) | |
memcg: fix split_huge_page_refcounts()
This patch started off as a cleanup: __split_huge_page_refcounts() has to
cope with two scenarios, when the hugepage being split is already on LRU,
and when it is not; but why does it have to split that accounting across
three different sites? Consolidate it in lru_add_page_tail(), handling
evictable and unevictable alike, and use standard add_page_to_lru_list()
when accounting is needed (when the head is not yet on LRU).
But a recent regression in -next, I guess the removal of PageCgroupAcctLRU
test from mem_cgroup_split_huge_fixup(), makes this now a necessary fix:
under load, the MEM_CGROUP_ZSTAT count was wrapping to a huge number,
messing up reclaim calculations and causing a freeze at rmdir of cgroup.
Add a VM_BUG_ON to mem_cgroup_lru_del_list() when we're about to wrap that
count - this has not been the only such incident. Document that
lru_add_page_tail() is for Transparent HugePages by #ifdef around it.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 12 |
1 files changed, 2 insertions, 10 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 609c49f492e..9f2f6469740 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1071,6 +1071,7 @@ void mem_cgroup_lru_del_list(struct page *page, enum lru_list lru) VM_BUG_ON(!memcg); mz = page_cgroup_zoneinfo(memcg, page); /* huge page split is done under lru_lock. so, we have no races. */ + VM_BUG_ON(MEM_CGROUP_ZSTAT(mz, lru) < (1 << compound_order(page))); MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page); } @@ -2465,9 +2466,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, void mem_cgroup_split_huge_fixup(struct page *head) { struct page_cgroup *head_pc = lookup_page_cgroup(head); - struct mem_cgroup_per_zone *mz; struct page_cgroup *pc; - enum lru_list lru; int i; if (mem_cgroup_disabled()) @@ -2478,15 +2477,8 @@ void mem_cgroup_split_huge_fixup(struct page *head) smp_wmb();/* see __commit_charge() */ pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT; } - /* - * Tail pages will be added to LRU. - * We hold lru_lock,then,reduce counter directly. - */ - lru = page_lru(head); - mz = page_cgroup_zoneinfo(head_pc->mem_cgroup, head); - MEM_CGROUP_ZSTAT(mz, lru) -= HPAGE_PMD_NR - 1; } -#endif +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ /** * mem_cgroup_move_account - move account of the page |