From d31f56dbf8bafaacb0c617f9a6f137498d5c7aed Mon Sep 17 00:00:00 2001 From: Daisuke Nishimura Date: Tue, 15 Dec 2009 16:47:12 -0800 Subject: [PATCH] memcg: avoid oom-killing innocent task in case of use_hierarchy task_in_mem_cgroup(), which is called by select_bad_process() to check whether a task can be a candidate for being oom-killed from memcg's limit, checks "curr->use_hierarchy"("curr" is the mem_cgroup the task belongs to). But this check return true(it's false positive) when: /aa use_hierarchy == 0 <- hitting limit /aa/00 use_hierarchy == 1 <- the task belongs to This leads to killing an innocent task in aa/00. This patch is a fix for this bug. And this patch also fixes the arg for mem_cgroup_print_oom_info(). We should print information of mem_cgroup which the task being killed, not current, belongs to. Signed-off-by: Daisuke Nishimura Acked-by: Balbir Singh Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 10 ++++++++-- mm/oom_kill.c | 13 +++++++------ 2 files changed, 15 insertions(+), 8 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6273984f2e3..a294b757607 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -760,7 +760,13 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem) task_unlock(task); if (!curr) return 0; - if (curr->use_hierarchy) + /* + * We should check use_hierarchy of "mem" not "curr". Because checking + * use_hierarchy of "curr" here make this function true if hierarchy is + * enabled in "curr" and "curr" is a child of "mem" in *cgroup* + * hierarchy(even if use_hierarchy is disabled in "mem"). + */ + if (mem->use_hierarchy) ret = css_is_ancestor(&curr->css, &mem->css); else ret = (curr == mem); @@ -1009,7 +1015,7 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p) static char memcg_name[PATH_MAX]; int ret; - if (!memcg) + if (!memcg || !p) return; diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 25c679e0288..f52481b1c1e 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -356,7 +356,8 @@ static void dump_tasks(const struct mem_cgroup *mem) } while_each_thread(g, p); } -static void dump_header(gfp_t gfp_mask, int order, struct mem_cgroup *mem) +static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order, + struct mem_cgroup *mem) { pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, " "oom_adj=%d\n", @@ -365,7 +366,7 @@ static void dump_header(gfp_t gfp_mask, int order, struct mem_cgroup *mem) cpuset_print_task_mems_allowed(current); task_unlock(current); dump_stack(); - mem_cgroup_print_oom_info(mem, current); + mem_cgroup_print_oom_info(mem, p); show_mem(); if (sysctl_oom_dump_tasks) dump_tasks(mem); @@ -440,7 +441,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, struct task_struct *c; if (printk_ratelimit()) - dump_header(gfp_mask, order, mem); + dump_header(p, gfp_mask, order, mem); /* * If the task is already exiting, don't alarm the sysadmin or kill @@ -576,7 +577,7 @@ retry: /* Found nothing?!?! Either we hang forever, or we panic. */ if (!p) { read_unlock(&tasklist_lock); - dump_header(gfp_mask, order, NULL); + dump_header(NULL, gfp_mask, order, NULL); panic("Out of memory and no killable processes...\n"); } @@ -644,7 +645,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, return; if (sysctl_panic_on_oom == 2) { - dump_header(gfp_mask, order, NULL); + dump_header(NULL, gfp_mask, order, NULL); panic("out of memory. Compulsory panic_on_oom is selected.\n"); } @@ -663,7 +664,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, case CONSTRAINT_NONE: if (sysctl_panic_on_oom) { - dump_header(gfp_mask, order, NULL); + dump_header(NULL, gfp_mask, order, NULL); panic("out of memory. panic_on_oom is selected\n"); } /* Fall-through */