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authorMandeep Singh Baines <msb@chromium.org>2011-01-13 15:46:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 17:32:35 -0800
commitdabb16f639820267b3850d804571c70bd93d4e07 (patch)
tree7da59e6133cd2f820389574ac9206c56e046f5d4 /fs/proc
parentd0a21265dfb5fa8ae54e90d0fb6d1c215b10a28a (diff)
oom: allow a non-CAP_SYS_RESOURCE proces to oom_score_adj down
We'd like to be able to oom_score_adj a process up/down as it enters/leaves the foreground. Currently, it is not possible to oom_adj down without CAP_SYS_RESOURCE. This patch allows a task to decrease its oom_score_adj back to the value that a CAP_SYS_RESOURCE thread set it to or its inherited value at fork. Assuming the thread that has forked it has oom_score_adj of 0, each process could decrease it back from 0 upon activation unless a CAP_SYS_RESOURCE thread elevated it to something higher. Alternative considered: * a setuid binary * a daemon with CAP_SYS_RESOURCE Since you don't wan't all processes to be able to reduce their oom_adj, a setuid or daemon implementation would be complex. The alternatives also have much higher overhead. This patch updated from original patch based on feedback from David Rientjes. Signed-off-by: Mandeep Singh Baines <msb@chromium.org> Acked-by: David Rientjes <rientjes@google.com> 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>
Diffstat (limited to 'fs/proc')
-rw-r--r--fs/proc/base.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 93f1cdd5d3d..9d096e82b20 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1151,7 +1151,7 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
goto err_task_lock;
}
- if (oom_score_adj < task->signal->oom_score_adj &&
+ if (oom_score_adj < task->signal->oom_score_adj_min &&
!capable(CAP_SYS_RESOURCE)) {
err = -EACCES;
goto err_sighand;
@@ -1164,6 +1164,8 @@ static ssize_t oom_score_adj_write(struct file *file, const char __user *buf,
atomic_dec(&task->mm->oom_disable_count);
}
task->signal->oom_score_adj = oom_score_adj;
+ if (has_capability_noaudit(current, CAP_SYS_RESOURCE))
+ task->signal->oom_score_adj_min = oom_score_adj;
/*
* Scale /proc/pid/oom_adj appropriately ensuring that OOM_DISABLE is
* always attainable.