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authorNick Piggin <npiggin@suse.de>2006-09-29 02:01:14 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-29 09:18:21 -0700
commitb78483a4ba60d5d90930262a533a784e1d9df660 (patch)
tree0b2cb0f3cf2852bf4138c13179221e58a37f402a /mm
parent01017a227044d64face2588fab9427a1da1bdb9f (diff)
downloadconfigs-b78483a4ba60d5d90930262a533a784e1d9df660.tar.gz
[PATCH] oom: don't kill current when another OOM in progress
A previous patch to allow an exiting task to OOM kill itself (and thereby avoid a little deadlock) introduced a problem. We don't want the PF_EXITING task, even if it is 'current', to access mem reserves if there is already a TIF_MEMDIE process in the system sucking up reserves. Also make the commenting a little bit clearer, and note that our current scheme of effectively single threading the OOM killer is not itself perfect. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/oom_kill.c23
1 files changed, 17 insertions, 6 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index a5493a3b485..20f41b082e1 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -216,6 +216,18 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
continue;
/*
+ * This task already has access to memory reserves and is
+ * being killed. Don't allow any other task access to the
+ * memory reserve.
+ *
+ * Note: this may have a chance of deadlock if it gets
+ * blocked waiting for another task which itself is waiting
+ * for memory. Is there a better alternative?
+ */
+ if (test_tsk_thread_flag(p, TIF_MEMDIE))
+ return ERR_PTR(-1UL);
+
+ /*
* This is in the process of releasing memory so wait for it
* to finish before killing some other task by mistake.
*
@@ -223,16 +235,15 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
* go ahead if it is exiting: this will simply set TIF_MEMDIE,
* which will allow it to gain access to memory reserves in
* the process of exiting and releasing its resources.
- * Otherwise we could get an OOM deadlock.
+ * Otherwise we could get an easy OOM deadlock.
*/
- if ((p->flags & PF_EXITING) && p == current) {
+ if (p->flags & PF_EXITING) {
+ if (p != current)
+ return ERR_PTR(-1UL);
+
chosen = p;
*ppoints = ULONG_MAX;
- break;
}
- if ((p->flags & PF_EXITING) ||
- test_tsk_thread_flag(p, TIF_MEMDIE))
- return ERR_PTR(-1UL);
if (p->oomkilladj == OOM_DISABLE)
continue;