From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 3F22C6B01B4 for ; Wed, 2 Jun 2010 11:56:21 -0400 (EDT) Date: Wed, 2 Jun 2010 17:54:55 +0200 From: Oleg Nesterov Subject: Re: [PATCH] oom: remove PF_EXITING check completely Message-ID: <20100602155455.GB9622@redhat.com> References: <20100601093951.2430.A69D9226@jp.fujitsu.com> <20100601201843.GA20732@redhat.com> <20100602200732.F518.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100602200732.F518.A69D9226@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: LKML , linux-mm , David Rientjes , Andrew Morton , KAMEZAWA Hiroyuki , Nick Piggin List-ID: On 06/02, KOSAKI Motohiro wrote: > > Today, I've thought to make some bandaid patches for this issue. but > yes, I've reached the same conclusion. > > If we think multithread and core dump situation, all fixes are just > bandaid. We can't remove deadlock chance completely. > > The deadlock is certenaly worst result, then, minor PF_EXITING optimization > doesn't have so much worth. Agreed! I was always wondering if it really helps in practice. > Subject: [PATCH] oom: remove PF_EXITING check completely > > PF_EXITING is wrong check if the task have multiple threads. This patch > removes it. > > Suggested-by: Oleg Nesterov > Signed-off-by: KOSAKI Motohiro > Cc: Nick Piggin > --- > mm/oom_kill.c | 27 --------------------------- > 1 files changed, 0 insertions(+), 27 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 9e7f0f9..b06f8d1 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -302,24 +302,6 @@ static struct task_struct *select_bad_process(unsigned long *ppoints, > 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. > - * > - * 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 easy OOM deadlock. > - */ > - if ((p->flags & PF_EXITING) && p->mm) { > - if (p != current) > - return ERR_PTR(-1UL); > - > - chosen = p; > - *ppoints = ULONG_MAX; > - } > - > points = badness(p, uptime.tv_sec); > if (points > *ppoints || !chosen) { > chosen = p; > @@ -436,15 +418,6 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, > if (printk_ratelimit()) > dump_header(p, gfp_mask, order, mem); > > - /* > - * 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_process(p, mem, 0); > - return 0; > - } > - > printk(KERN_ERR "%s: kill process %d (%s) score %li or a child\n", > message, task_pid_nr(p), p->comm, points); > > -- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org