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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2009-09-21 17:03:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:17:39 -0700
commit28b83c5193e7ab951e402252278f2cc79dc4d298 (patch)
tree10080e8d3957c2a03f8419ab44c9ecb0ffcdaee0 /fs
parentf168e1b6390e2d79cf57e48e6ae6d9b0a9e2851a (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')
-rw-r--r--fs/proc/base.c24
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;