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authorNick Piggin <npiggin@suse.de>2006-09-25 23:31:29 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-26 08:48:48 -0700
commit50ec3bbffbe8a96347c54832d48110a5bc9e9ff8 (patch)
tree3941902b1c68525472ea3a502e76faa7fe675cd1 /mm
parent7887a3da753e1ba8244556cc9a2b38c815bfe256 (diff)
[PATCH] oom: handle current exiting
If current *is* exiting, it should actually be allowed to access reserved memory rather than OOM kill something else. Can't do this via a straight check in page_alloc.c because that would allow multiple tasks to use up reserves. Instead cause current to OOM-kill itself which will mark it as TIF_MEMDIE. The current procedure of simply aborting the OOM-kill if a task is exiting can lead to OOM deadlocks. In the case of killing a PF_EXITING task, don't make a lot of noise about it. This becomes more important in future patches, where we can "kill" OOM_DISABLE tasks. 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.c35
1 files changed, 31 insertions, 4 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4f815b06ac1b..0131bae2a16d 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -210,11 +210,26 @@ static struct task_struct *select_bad_process(unsigned long *ppoints)
/*
* This is in the process of releasing memory so wait for it
* to finish before killing some other task by mistake.
+ *
+ * However, if p is the current task, we allow the 'kill' to
+ * 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.
*/
releasing = test_tsk_thread_flag(p, TIF_MEMDIE) ||
p->flags & PF_EXITING;
- if (releasing && !(p->flags & PF_DEAD))
+ if (releasing) {
+ /* PF_DEAD tasks have already released their mm */
+ if (p->flags & PF_DEAD)
+ continue;
+ if (p->flags & PF_EXITING && p == current) {
+ chosen = p;
+ *ppoints = ULONG_MAX;
+ break;
+ }
return ERR_PTR(-1UL);
+ }
if (p->flags & PF_SWAPOFF)
return p;
@@ -248,8 +263,11 @@ static void __oom_kill_task(struct task_struct *p, const char *message)
return;
}
task_unlock(p);
- printk(KERN_ERR "%s: Killed process %d (%s).\n",
+
+ if (message) {
+ printk(KERN_ERR "%s: Killed process %d (%s).\n",
message, p->pid, p->comm);
+ }
/*
* We give our sacrificial lamb high priority and access to
@@ -300,8 +318,17 @@ static int oom_kill_process(struct task_struct *p, unsigned long points,
struct task_struct *c;
struct list_head *tsk;
- printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li and "
- "children.\n", p->pid, p->comm, points);
+ /*
+ * If the task is already exiting, don't alarm the sysadmin or kill
+ * its children or threads, just set TIF_MEMDIE so it can die quickly
+ */
+ if (p->flags & PF_EXITING) {
+ __oom_kill_task(p, NULL);
+ return 0;
+ }
+
+ printk(KERN_ERR "Out of Memory: Kill process %d (%s) score %li"
+ " and children.\n", p->pid, p->comm, points);
/* Try to kill a child first */
list_for_each(tsk, &p->children) {
c = list_entry(tsk, struct task_struct, sibling);