The patch titled
oom: handle current exiting
has been removed from the -mm tree. Its filename is
oom-handle-current-exiting.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: oom: handle current exiting
From: Nick Piggin <npiggin@xxxxxxx>
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@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
mm/oom_kill.c | 35 +++++++++++++++++++++++++++++++----
1 file changed, 31 insertions(+), 4 deletions(-)
diff -puN mm/oom_kill.c~oom-handle-current-exiting mm/oom_kill.c
--- a/mm/oom_kill.c~oom-handle-current-exiting
+++ a/mm/oom_kill.c
@@ -210,11 +210,26 @@ static struct task_struct *select_bad_pr
/*
* 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_
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 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);
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
origin.patch
git-block.patch
page-invalidation-cleanup.patch
mm-micro-optimise-zone_watermark_ok.patch
radix-tree-rcu-lockless-readside.patch
select_bad_process-cleanup-releasing-check.patch
oom-dont-kill-current-when-another-oom-in-progress.patch
sched-force-sbin-init-off-isolated-cpus.patch
-
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