From 4c9c535968cacf507c5febe49e6ec5123eadf207 Mon Sep 17 00:00:00 2001 From: Suleiman Souhlal Date: Tue, 18 Dec 2012 14:21:41 -0800 Subject: [PATCH] memcg: reclaim when more than one page needed mem_cgroup_do_charge() was written before kmem accounting, and expects three cases: being called for 1 page, being called for a stock of 32 pages, or being called for a hugepage. If we call for 2 or 3 pages (and both the stack and several slabs used in process creation are such, at least with the debug options I had), it assumed it's being called for stock and just retried without reclaiming. Fix that by passing down a minsize argument in addition to the csize. And what to do about that (csize == PAGE_SIZE && ret) retry? If it's needed at all (and presumably is since it's there, perhaps to handle races), then it should be extended to more than PAGE_SIZE, yet how far? And should there be a retry count limit, of what? For now retry up to COSTLY_ORDER (as page_alloc.c does) and make sure not to do it if __GFP_NORETRY. v4: fixed nr pages calculation pointed out by Christoph Lameter. Signed-off-by: Suleiman Souhlal Signed-off-by: Glauber Costa Acked-by: Kamezawa Hiroyuki Acked-by: Michal Hocko Acked-by: Johannes Weiner Acked-by: David Rientjes Cc: Tejun Heo Cc: Christoph Lameter Cc: Frederic Weisbecker Cc: Greg Thelen Cc: JoonSoo Kim Cc: Mel Gorman Cc: Pekka Enberg Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 92887b286246..20e3619870ae 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2258,7 +2258,8 @@ enum { }; static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, - unsigned int nr_pages, bool oom_check) + unsigned int nr_pages, unsigned int min_pages, + bool oom_check) { unsigned long csize = nr_pages * PAGE_SIZE; struct mem_cgroup *mem_over_limit; @@ -2281,18 +2282,18 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, } else mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); /* - * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch - * of regular pages (CHARGE_BATCH), or a single regular page (1). - * * Never reclaim on behalf of optional batching, retry with a * single page instead. */ - if (nr_pages == CHARGE_BATCH) + if (nr_pages > min_pages) return CHARGE_RETRY; if (!(gfp_mask & __GFP_WAIT)) return CHARGE_WOULDBLOCK; + if (gfp_mask & __GFP_NORETRY) + return CHARGE_NOMEM; + ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); if (mem_cgroup_margin(mem_over_limit) >= nr_pages) return CHARGE_RETRY; @@ -2305,7 +2306,7 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, * unlikely to succeed so close to the limit, and we fall back * to regular pages anyway in case of failure. */ - if (nr_pages == 1 && ret) + if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret) return CHARGE_RETRY; /* @@ -2439,7 +2440,8 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; } - ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check); + ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, nr_pages, + oom_check); switch (ret) { case CHARGE_OK: break; -- GitLab