diff options
| author | David Rientjes <rientjes@google.com> | 2010-10-26 14:21:26 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-26 16:52:05 -0700 |
| commit | d19d5476f4b9f91d2de92b91588bb118beba6c0d (patch) | |
| tree | b267c225c2b7507f7e4900676649b20e56e06ba2 | |
| parent | 723548bff1dde9ab6bdb23f4bb92277c4da49473 (diff) | |
oom: fix locking for oom_adj and oom_score_adj
The locking order in oom_adjust_write() and oom_score_adj_write() for
task->alloc_lock and task->sighand->siglock is reversed, and lockdep
notices that irqs could encounter an ABBA scenario.
This fixes the locking order so that we always take task_lock(task) prior
to lock_task_sighand(task).
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/base.c | 40 |
1 files changed, 21 insertions, 19 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 34d11ac31f2e..53dc8ad40ae6 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1042,9 +1042,16 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, err = -ESRCH; goto out; } + + task_lock(task); + if (!task->mm) { + err = -EINVAL; + goto err_task_lock; + } + if (!lock_task_sighand(task, &flags)) { err = -ESRCH; - goto err_task_struct; + goto err_task_lock; } if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) { @@ -1052,12 +1059,6 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, goto err_sighand; } - task_lock(task); - if (!task->mm) { - err = -EINVAL; - goto err_task_lock; - } - if (oom_adjust != task->signal->oom_adj) { if (oom_adjust == OOM_DISABLE) atomic_inc(&task->mm->oom_disable_count); @@ -1083,11 +1084,10 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, else task->signal->oom_score_adj = (oom_adjust * OOM_SCORE_ADJ_MAX) / -OOM_DISABLE; -err_task_lock: - task_unlock(task); err_sighand: unlock_task_sighand(task, &flags); -err_task_struct: +err_task_lock: + task_unlock(task); put_task_struct(task); out: return err < 0 ? err : count; @@ -1150,21 +1150,24 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, err = -ESRCH; goto out; } + + task_lock(task); + if (!task->mm) { + err = -EINVAL; + goto err_task_lock; + } + if (!lock_task_sighand(task, &flags)) { err = -ESRCH; - goto err_task_struct; + goto err_task_lock; } + if (oom_score_adj < task->signal->oom_score_adj && !capable(CAP_SYS_RESOURCE)) { err = -EACCES; goto err_sighand; } - task_lock(task); - if (!task->mm) { - err = -EINVAL; - goto err_task_lock; - } if (oom_score_adj != task->signal->oom_score_adj) { if (oom_score_adj == OOM_SCORE_ADJ_MIN) atomic_inc(&task->mm->oom_disable_count); @@ -1181,11 +1184,10 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf, else task->signal->oom_adj = (oom_score_adj * OOM_ADJUST_MAX) / OOM_SCORE_ADJ_MAX; -err_task_lock: - task_unlock(task); err_sighand: unlock_task_sighand(task, &flags); -err_task_struct: +err_task_lock: + task_unlock(task); put_task_struct(task); out: return err < 0 ? err : count; |