linux-kernel - [PATCH 09/12] oom: remove PF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20100603152436.7262.A69D9226@jp.fujitsu.com>
Date:	Thu,  3 Jun 2010 15:25:18 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	"Luis Claudio R. Goncalves" <lclaudio@...g.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, Oleg Nesterov <oleg@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Nick Piggin <npiggin@...e.de>
Cc:	kosaki.motohiro@...fujitsu.com
Subject: [PATCH 09/12] oom: remove PF_EXITING check completely

Currently, PF_EXITING check is completely broken. because 1) It only
care main-thread and ignore sub-threads 2) If user enable core-dump
feature, it can makes deadlock because the task during coredump ignore
SIGKILL.

The deadlock is certenaly worst result, then, minor PF_EXITING
optimization worth is relatively ignorable.

This patch removes it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Acked-by: Oleg Nesterov <oleg@...hat.com>
---
 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 6360c56..5d723fb 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) {
-			if (p != current)
-				return ERR_PTR(-1UL);
-
-			chosen = p;
-			*ppoints = ULONG_MAX;
-		}
-
 		points = badness(p, uptime.tv_sec);
 		if (points > *ppoints || !chosen) {
 			chosen = p;
@@ -444,15 +426,6 @@ 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);
 
-- 
1.6.5.2



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/