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author | Nick Piggin <npiggin@suse.de> | 2006-09-25 23:31:29 -0700 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-26 08:48:48 -0700 |
commit | 50ec3bbffbe8a96347c54832d48110a5bc9e9ff8 (patch) | |
tree | 3941902b1c68525472ea3a502e76faa7fe675cd1 /mm | |
parent | 7887a3da753e1ba8244556cc9a2b38c815bfe256 (diff) | |
download | op-kernel-dev-50ec3bbffbe8a96347c54832d48110a5bc9e9ff8.zip op-kernel-dev-50ec3bbffbe8a96347c54832d48110a5bc9e9ff8.tar.gz |
[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.c | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 4f815b0..0131bae 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); |