From e767e0561d7fd2333df1921f1ab4176211f9036b Mon Sep 17 00:00:00 2001 From: Daisuke Nishimura Date: Thu, 28 May 2009 14:34:28 -0700 Subject: memcg: fix deadlock between lock_page_cgroup and mapping tree_lock mapping->tree_lock can be acquired from interrupt context. Then, following dead lock can occur. Assume "A" as a page. CPU0: lock_page_cgroup(A) interrupted -> take mapping->tree_lock. CPU1: take mapping->tree_lock -> lock_page_cgroup(A) This patch tries to fix above deadlock by moving memcg's hook to out of mapping->tree_lock. charge/uncharge of pagecache/swapcache is protected by page lock, not tree_lock. After this patch, lock_page_cgroup() is not called under mapping->tree_lock. Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Daisuke Nishimura Cc: Balbir Singh Cc: Daisuke Nishimura Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 01c2d8f14685..4a747a27a22f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1488,8 +1488,9 @@ void mem_cgroup_uncharge_cache_page(struct page *page) __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE); } +#ifdef CONFIG_SWAP /* - * called from __delete_from_swap_cache() and drop "page" account. + * called after __delete_from_swap_cache() and drop "page" account. * memcg information is recorded to swap_cgroup of "ent" */ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) @@ -1506,6 +1507,7 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent) if (memcg) css_put(&memcg->css); } +#endif #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP /* -- cgit v1.2.3 From 46f7e602fb32e02145ef14f8c0ca6d399f0a96b9 Mon Sep 17 00:00:00 2001 From: Nikanth Karthikesan Date: Thu, 28 May 2009 14:34:41 -0700 Subject: memcg: fix build warning and avoid checking for mem != null again and again Fix build warning, "mem_cgroup_is_obsolete defined but not used" when CONFIG_DEBUG_VM is not set. Also avoid checking for !mem again and again. Signed-off-by: Nikanth Karthikesan Acked-by: Pekka Enberg Acked-by: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4a747a27a22f..78eb8552818b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -314,14 +314,6 @@ static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) return mem; } -static bool mem_cgroup_is_obsolete(struct mem_cgroup *mem) -{ - if (!mem) - return true; - return css_is_removed(&mem->css); -} - - /* * Call callback function against all cgroup under hierarchy tree. */ @@ -932,7 +924,7 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, if (unlikely(!mem)) return 0; - VM_BUG_ON(!mem || mem_cgroup_is_obsolete(mem)); + VM_BUG_ON(css_is_removed(&mem->css)); while (1) { int ret; -- cgit v1.2.3