diff options
author | KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> | 2009-09-21 17:03:13 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:39 -0700 |
commit | 28b83c5193e7ab951e402252278f2cc79dc4d298 (patch) | |
tree | 10080e8d3957c2a03f8419ab44c9ecb0ffcdaee0 /fs/proc | |
parent | f168e1b6390e2d79cf57e48e6ae6d9b0a9e2851a (diff) |
oom: move oom_adj value from task_struct to signal_struct
Currently, OOM logic callflow is here.
__out_of_memory()
select_bad_process() for each task
badness() calculate badness of one task
oom_kill_process() search child
oom_kill_task() kill target task and mm shared tasks with it
example, process-A have two thread, thread-A and thread-B and it have very
fat memory and each thread have following oom_adj and oom_score.
thread-A: oom_adj = OOM_DISABLE, oom_score = 0
thread-B: oom_adj = 0, oom_score = very-high
Then, select_bad_process() select thread-B, but oom_kill_task() refuse
kill the task because thread-A have OOM_DISABLE. Thus __out_of_memory()
call select_bad_process() again. but select_bad_process() select the same
task. It mean kernel fall in livelock.
The fact is, select_bad_process() must select killable task. otherwise
OOM logic go into livelock.
And root cause is, oom_adj shouldn't be per-thread value. it should be
per-process value because OOM-killer kill a process, not thread. Thus
This patch moves oomkilladj (now more appropriately named oom_adj) from
struct task_struct to struct signal_struct. it naturally prevent
select_bad_process() choose wrong task.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/base.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 6f742f6658a9..81cfff82875b 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -999,11 +999,17 @@ static ssize_t oom_adjust_read(struct file *file, char __user *buf, struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode); char buffer[PROC_NUMBUF]; size_t len; - int oom_adjust; + int oom_adjust = OOM_DISABLE; + unsigned long flags; if (!task) return -ESRCH; - oom_adjust = task->oomkilladj; + + if (lock_task_sighand(task, &flags)) { + oom_adjust = task->signal->oom_adj; + unlock_task_sighand(task, &flags); + } + put_task_struct(task); len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust); @@ -1017,6 +1023,7 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, struct task_struct *task; char buffer[PROC_NUMBUF], *end; int oom_adjust; + unsigned long flags; memset(buffer, 0, sizeof(buffer)); if (count > sizeof(buffer) - 1) @@ -1032,11 +1039,20 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf, task = get_proc_task(file->f_path.dentry->d_inode); if (!task) return -ESRCH; - if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) { + if (!lock_task_sighand(task, &flags)) { + put_task_struct(task); + return -ESRCH; + } + + if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) { + unlock_task_sighand(task, &flags); put_task_struct(task); return -EACCES; } - task->oomkilladj = oom_adjust; + + task->signal->oom_adj = oom_adjust; + + unlock_task_sighand(task, &flags); put_task_struct(task); if (end - buffer == 0) return -EIO; |