From 184101bf143ac96d62b3dcc17e7b3550f98d3350 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Wed, 6 May 2009 16:02:55 -0700 Subject: oom: prevent livelock when oom_kill_allocating_task is set When /proc/sys/vm/oom_kill_allocating_task is set for large systems that want to avoid the lengthy tasklist scan, it's possible to livelock if current is ineligible for oom kill. This normally happens when it is set to OOM_DISABLE, but is also possible if any threads are sharing the same ->mm with a different tgid. So change __out_of_memory() to fall back to the full task-list scan if it was unable to kill `current'. Cc: Nick Piggin Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 44 +++++++++++++++++++++----------------------- 1 file changed, 21 insertions(+), 23 deletions(-) (limited to 'mm/oom_kill.c') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 2f3166e308d..92bcf1db16b 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -514,34 +514,32 @@ void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask) */ static void __out_of_memory(gfp_t gfp_mask, int order) { - if (sysctl_oom_kill_allocating_task) { - oom_kill_process(current, gfp_mask, order, 0, NULL, - "Out of memory (oom_kill_allocating_task)"); - - } else { - unsigned long points; - struct task_struct *p; - -retry: - /* - * Rambo mode: Shoot down a process and hope it solves whatever - * issues we may have. - */ - p = select_bad_process(&points, NULL); + struct task_struct *p; + unsigned long points; - if (PTR_ERR(p) == -1UL) + if (sysctl_oom_kill_allocating_task) + if (!oom_kill_process(current, gfp_mask, order, 0, NULL, + "Out of memory (oom_kill_allocating_task)")) return; +retry: + /* + * Rambo mode: Shoot down a process and hope it solves whatever + * issues we may have. + */ + p = select_bad_process(&points, NULL); - /* Found nothing?!?! Either we hang forever, or we panic. */ - if (!p) { - read_unlock(&tasklist_lock); - panic("Out of memory and no killable processes...\n"); - } + if (PTR_ERR(p) == -1UL) + return; - if (oom_kill_process(p, gfp_mask, order, points, NULL, - "Out of memory")) - goto retry; + /* Found nothing?!?! Either we hang forever, or we panic. */ + if (!p) { + read_unlock(&tasklist_lock); + panic("Out of memory and no killable processes...\n"); } + + if (oom_kill_process(p, gfp_mask, order, points, NULL, + "Out of memory")) + goto retry; } /* -- cgit v1.2.3 From 6d2661ede5f20f968422e790af3334908c3bc857 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Thu, 28 May 2009 14:34:19 -0700 Subject: oom: fix possible oom_dump_tasks NULL pointer When /proc/sys/vm/oom_dump_tasks is enabled, it is possible to get a NULL pointer for tasks that have detached mm's since task_lock() is not held during the tasklist scan. Add the task_lock(). Acked-by: Nick Piggin Acked-by: Mel Gorman Cc: Rik van Riel Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) (limited to 'mm/oom_kill.c') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 92bcf1db16b..a7b2460e922 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -284,22 +284,28 @@ static void dump_tasks(const struct mem_cgroup *mem) printk(KERN_INFO "[ pid ] uid tgid total_vm rss cpu oom_adj " "name\n"); do_each_thread(g, p) { - /* - * total_vm and rss sizes do not exist for tasks with a - * detached mm so there's no need to report them. - */ - if (!p->mm) - continue; + struct mm_struct *mm; + if (mem && !task_in_mem_cgroup(p, mem)) continue; if (!thread_group_leader(p)) continue; task_lock(p); + mm = p->mm; + if (!mm) { + /* + * total_vm and rss sizes do not exist for tasks with no + * mm so there's no need to report them; they can't be + * oom killed anyway. + */ + task_unlock(p); + continue; + } printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n", - p->pid, __task_cred(p)->uid, p->tgid, - p->mm->total_vm, get_mm_rss(p->mm), (int)task_cpu(p), - p->oomkilladj, p->comm); + p->pid, __task_cred(p)->uid, p->tgid, mm->total_vm, + get_mm_rss(mm), (int)task_cpu(p), p->oomkilladj, + p->comm); task_unlock(p); } while_each_thread(g, p); } -- cgit v1.2.3