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authorMandeep Singh Baines <msb@chromium.org>2011-12-15 11:36:43 -0800
committerRohan Somvanshi <rsomvanshi@nvidia.com>2012-01-11 09:52:46 -0800
commit2d5ebc34329444db7f46e54ec19d4dc8e60c102a (patch)
tree0eb1097afc1688562e3c0251783e5e0fe4fc8db5 /kernel
parent0746a065d0f10996bae7422896eb885fbbcef393 (diff)
cgroups: fix a css_set not found bug in cgroup_attach_proc
commit e0197aae59e55c06db172bfbe1a1cdb8c0e1cab3 upstream. There is a BUG when migrating a PF_EXITING proc. Since css_set_prefetch() is not called for the PF_EXITING case, find_existing_css_set() will return NULL inside cgroup_task_migrate() causing a BUG. This bug is easy to reproduce. Create a zombie and echo its pid to cgroup.procs. $ cat zombie.c \#include <unistd.h> int main() { if (fork()) pause(); return 0; } $ We are hitting this bug pretty regularly on ChromeOS. This bug is already fixed by Tejun Heo's cgroup patchset which is targetted for the next merge window: https://lkml.org/lkml/2011/11/1/356 I've create a smaller patch here which just fixes this bug so that a fix can be merged into the current release and stable. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Downstream-Bug-Report: http://crosbug.com/23953 Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: containers@lists.linux-foundation.org Cc: cgroups@vger.kernel.org Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul Menage <paul@paulmenage.org> Cc: Olof Johansson <olofj@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> Change-Id: I61bf2d48574d6ce5418b988e9547937c2efdd084 Reviewed-on: http://git-master/r/74185 Reviewed-by: Automatic_Commit_Validation_User Reviewed-by: Rohan Somvanshi <rsomvanshi@nvidia.com> Tested-by: Rohan Somvanshi <rsomvanshi@nvidia.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c5
1 files changed, 0 insertions, 5 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index bab5a7911b84..225f47478f34 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2108,11 +2108,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
continue;
/* get old css_set pointer */
task_lock(tsk);
- if (tsk->flags & PF_EXITING) {
- /* ignore this task if it's going away */
- task_unlock(tsk);
- continue;
- }
oldcg = tsk->cgroups;
get_css_set(oldcg);
task_unlock(tsk);