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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2009-08-18 14:11:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-08-18 16:31:13 -0700
commit0753ba01e126020bf0f8150934903b48935b697d (patch)
treefbfd7e2d0abbe724a8c5e0e17fb9af522ed2e097 /fs/proc
parent89a4eb4b66e8f4d395e14a14d262dac4d6ca52f0 (diff)
mm: revert "oom: move oom_adj value"
The commit 2ff05b2b (oom: move oom_adj value) moveed the oom_adj value to the mm_struct. It was a very good first step for sanitize OOM. However Paul Menage reported the commit makes regression to his job scheduler. Current OOM logic can kill OOM_DISABLED process. Why? His program has the code of similar to the following. ... set_oom_adj(OOM_DISABLE); /* The job scheduler never killed by oom */ ... if (vfork() == 0) { set_oom_adj(0); /* Invoked child can be killed */ execve("foo-bar-cmd"); } .... vfork() parent and child are shared the same mm_struct. then above set_oom_adj(0) doesn't only change oom_adj for vfork() child, it's also change oom_adj for vfork() parent. Then, vfork() parent (job scheduler) lost OOM immune and it was killed. Actually, fork-setting-exec idiom is very frequently used in userland program. We must not break this assumption. Then, this patch revert commit 2ff05b2b and related commit. Reverted commit list --------------------- - commit 2ff05b2b4e (oom: move oom_adj value from task_struct to mm_struct) - commit 4d8b9135c3 (oom: avoid unnecessary mm locking and scanning for OOM_DISABLE) - commit 8123681022 (oom: only oom kill exiting tasks with attached memory) - commit 933b787b57 (mm: copy over oom_adj value at fork time) 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: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Nick Piggin <npiggin@suse.de> Cc: Mel Gorman <mel@csn.ul.ie> 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.c19
1 files changed, 3 insertions, 16 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 175db258942..6f742f6658a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1003,12 +1003,7 @@ static ssize_t oom_adjust_read(struct file *file, char __user *buf,
if (!task)
return -ESRCH;
- task_lock(task);
- if (task->mm)
- oom_adjust = task->mm->oom_adj;
- else
- oom_adjust = OOM_DISABLE;
- task_unlock(task);
+ oom_adjust = task->oomkilladj;
put_task_struct(task);
len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
@@ -1037,19 +1032,11 @@ 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;
- task_lock(task);
- if (!task->mm) {
- task_unlock(task);
- put_task_struct(task);
- return -EINVAL;
- }
- if (oom_adjust < task->mm->oom_adj && !capable(CAP_SYS_RESOURCE)) {
- task_unlock(task);
+ if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) {
put_task_struct(task);
return -EACCES;
}
- task->mm->oom_adj = oom_adjust;
- task_unlock(task);
+ task->oomkilladj = oom_adjust;
put_task_struct(task);
if (end - buffer == 0)
return -EIO;