linux-kernel - Re: v3.4-rc2 out-of-memory problems (was Re: 3.4-rc1 sticks-and-crashs)

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Message-ID: <alpine.DEB.2.00.1204091636160.21813@chino.kir.corp.google.com>
Date:	Mon, 9 Apr 2012 16:37:04 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Colin Cross <ccross@...gle.com>
cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	werner <w.landgraf@...ru>, Rik van Riel <riel@...hat.com>,
	Hugh Dickins <hughd@...gle.com>, linux-kernel@...r.kernel.org,
	Oleg Nesterov <oleg@...hat.com>,
	Rabin Vincent <rabin.vincent@...ricsson.com>,
	Christian Bejram <christian.bejram@...ricsson.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org
Subject: Re: v3.4-rc2 out-of-memory problems (was Re: 3.4-rc1
 sticks-and-crashs)

On Mon, 9 Apr 2012, Colin Cross wrote:

> This was a known issue in 2010, in the android tree the use of
> task_handoff_register was dropped one day after it was added and
> replaced with a new task_free_register hook.

Why can't you just do this?  Are you concerned about the possibility of 
depleting all memory reserves?
---
 drivers/staging/android/lowmemorykiller.c |   47 ++++-------------------------
 1 file changed, 6 insertions(+), 41 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -55,7 +55,6 @@ static int lowmem_minfree[6] = {
 };
 static int lowmem_minfree_size = 4;
 
-static struct task_struct *lowmem_deathpending;
 static unsigned long lowmem_deathpending_timeout;
 
 #define lowmem_print(level, x...)			\
@@ -64,24 +63,6 @@ static unsigned long lowmem_deathpending_timeout;
 			printk(x);			\
 	} while (0)
 
-static int
-task_notify_func(struct notifier_block *self, unsigned long val, void *data);
-
-static struct notifier_block task_nb = {
-	.notifier_call	= task_notify_func,
-};
-
-static int
-task_notify_func(struct notifier_block *self, unsigned long val, void *data)
-{
-	struct task_struct *task = data;
-
-	if (task == lowmem_deathpending)
-		lowmem_deathpending = NULL;
-
-	return NOTIFY_OK;
-}
-
 static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 {
 	struct task_struct *tsk;
@@ -97,19 +78,6 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 	int other_file = global_page_state(NR_FILE_PAGES) -
 						global_page_state(NR_SHMEM);
 
-	/*
-	 * If we already have a death outstanding, then
-	 * bail out right away; indicating to vmscan
-	 * that we have nothing further to offer on
-	 * this pass.
-	 *
-	 * Note: Currently you need CONFIG_PROFILING
-	 * for this to work correctly.
-	 */
-	if (lowmem_deathpending &&
-	    time_before_eq(jiffies, lowmem_deathpending_timeout))
-		return 0;
-
 	if (lowmem_adj_size < array_size)
 		array_size = lowmem_adj_size;
 	if (lowmem_minfree_size < array_size)
@@ -148,6 +116,11 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 		if (!p)
 			continue;
 
+		if (test_tsk_thread_flag(p, TIF_MEMDIE) &&
+		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {
+			task_unlock(p);
+			return 0;
+		}
 		oom_score_adj = p->signal->oom_score_adj;
 		if (oom_score_adj < min_score_adj) {
 			task_unlock(p);
@@ -174,15 +147,9 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
 		lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
 			     selected->pid, selected->comm,
 			     selected_oom_score_adj, selected_tasksize);
-		/*
-		 * If CONFIG_PROFILING is off, then we don't want to stall
-		 * the killer by setting lowmem_deathpending.
-		 */
-#ifdef CONFIG_PROFILING
-		lowmem_deathpending = selected;
 		lowmem_deathpending_timeout = jiffies + HZ;
-#endif
 		send_sig(SIGKILL, selected, 0);
+		set_tsk_thread_flag(selected, TIF_MEMDIE);
 		rem -= selected_tasksize;
 	}
 	lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
@@ -198,7 +165,6 @@ static struct shrinker lowmem_shrinker = {
 
 static int __init lowmem_init(void)
 {
-	task_handoff_register(&task_nb);
 	register_shrinker(&lowmem_shrinker);
 	return 0;
 }
@@ -206,7 +172,6 @@ static int __init lowmem_init(void)
 static void __exit lowmem_exit(void)
 {
 	unregister_shrinker(&lowmem_shrinker);
-	task_handoff_unregister(&task_nb);
 }
 
 module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
--
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