From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756082AbaIWO3H (ORCPT ); Tue, 23 Sep 2014 10:29:07 -0400 Received: from mx1.mxmail.xiaomi.com ([58.68.235.87]:45898 "EHLO mx1.mxmail.xiaomi.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1755997AbaIWO3F (ORCPT ); Tue, 23 Sep 2014 10:29:05 -0400 From: =?gb2312?B?1uy71A==?= To: Weijie Yang CC: Greg KH , "rientjes@google.com" , "vinayakm.list@gmail.com" , "weijie.yang@samsung.com" , "devel@driverdev.osuosl.org" , "linux-kernel@vger.kernel.org" , "teawater@gmail.com" Subject: Re: [PATCH] Fix the issue that lowmemkiller fell into a cycle that try to kill a task Thread-Topic: [PATCH] Fix the issue that lowmemkiller fell into a cycle that try to kill a task Thread-Index: AQHP1toi3qW7tRqemUGYwU3B97qppQ== Date: Tue, 23 Sep 2014 14:28:49 +0000 Message-ID: References: <1411441029-8428-1-git-send-email-zhuhui@xiaomi.com> <20140923041738.GA6779@kroah.com> Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [114.243.7.15] x-esetresult: clean, is OK x-esetid: E374883E57221D3FB337D1 Content-Type: text/plain; charset="gb2312" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id s8NETC7j005380 On 09/23/14 16:00, Weijie Yang wrote: > On Tue, Sep 23, 2014 at 12:48 PM, wrote: >> >> >> On 09/23/14 12:18, Greg KH wrote: >>> On Tue, Sep 23, 2014 at 10:57:09AM +0800, Hui Zhu wrote: >>>> The cause of this issue is when free memroy size is low and a lot of task is >>>> trying to shrink the memory, the task that is killed by lowmemkiller cannot get >>>> CPU to exit itself. >>>> >>>> Fix this issue with change the scheduling policy to SCHED_FIFO if a task's flag >>>> is TIF_MEMDIE in lowmemkiller. >>>> >>>> Signed-off-by: Hui Zhu >>>> --- >>>> drivers/staging/android/lowmemorykiller.c | 4 ++++ >>>> 1 file changed, 4 insertions(+) >>>> >>>> diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c >>>> index b545d3d..ca1ffac 100644 >>>> --- a/drivers/staging/android/lowmemorykiller.c >>>> +++ b/drivers/staging/android/lowmemorykiller.c >>>> @@ -129,6 +129,10 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) >>>> >>>> if (test_tsk_thread_flag(p, TIF_MEMDIE) && >>>> time_before_eq(jiffies, lowmem_deathpending_timeout)) { >>>> + struct sched_param param = { .sched_priority = 1 }; >>>> + >>>> + if (p->policy == SCHED_NORMAL) >>>> + sched_setscheduler(p, SCHED_FIFO, ¶m); >>> >>> This seems really specific to a specific scheduler pattern now. Isn't >>> there some other way to resolve this? > > hui, how about modify lowmem_deathpending_timeout if we don't > touch scheduler pattern? I tried to change line "lowmem_deathpending_timeout = jiffies + HZ" to "lowmem_deathpending_timeout = jiffies + HZ * 10". But the issue can be reproduced sometimes. Could you give me some comments on this part? > >> I tried to let the task that call lowmemkiller sleep some time when it >> try to kill same task. But it doesn't work. >> I think the issue is that the free memroy size is too low to make more >> and more tasks come to call lowmemkiller. > > I am not opposed to the idea that the task which is selected to be killed > should exit ASAP. > > I want to make it clear, what is problem for the existing code and which > effect we can get by applying this patch. > 1. LMK count is increased, which can be reduced by applying this patch? I think the free mem size will grow faster than without this patch. > 2. app become more sluggish? I didn't get that in my part. > > By the way, whether we need to modify out_of_memory() which also > try to kill task? I am not sure because LMK handle the memory issue early than OOM. But I think this issue will not affect OOM because OOM has oom_zonelist_trylock and oom_zonelist_unlock. Thanks, Hui > >> Thanks, >> Hui >> >>> >>> thanks, >>> >>> greg k-h >>> >{.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I