From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f69.google.com (mail-it0-f69.google.com [209.85.214.69]) by kanga.kvack.org (Postfix) with ESMTP id 0BA986B0253 for ; Wed, 14 Sep 2016 03:21:24 -0400 (EDT) Received: by mail-it0-f69.google.com with SMTP id e20so27880057itc.0 for ; Wed, 14 Sep 2016 00:21:24 -0700 (PDT) Received: from szxga03-in.huawei.com (szxga03-in.huawei.com. [119.145.14.66]) by mx.google.com with ESMTPS id r7si17356253oig.5.2016.09.14.00.21.06 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 14 Sep 2016 00:21:07 -0700 (PDT) Message-ID: <57D8F8AE.1090404@huawei.com> Date: Wed, 14 Sep 2016 15:13:50 +0800 From: zhong jiang MIME-Version: 1.0 Subject: Re: [PATCH] mm: fix oom work when memory is under pressure References: <1473173226-25463-1-git-send-email-zhongjiang@huawei.com> <20160909114410.GG4844@dhcp22.suse.cz> <57D67A8A.7070500@huawei.com> <20160912111327.GG14524@dhcp22.suse.cz> <57D6B0C4.6040400@huawei.com> <20160912174445.GC14997@dhcp22.suse.cz> <57D7FB71.9090102@huawei.com> <20160913132854.GB6592@dhcp22.suse.cz> In-Reply-To: <20160913132854.GB6592@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: akpm@linux-foundation.org, vbabka@suse.cz, rientjes@google.com, linux-mm@kvack.org, Xishi Qiu , Hanjun Guo On 2016/9/13 21:28, Michal Hocko wrote: > On Tue 13-09-16 21:13:21, zhong jiang wrote: >> On 2016/9/13 1:44, Michal Hocko wrote: > [...] >>> If you want to solve this problem properly then you would have to give >>> tasks which are looping in the page allocator access to some portion of >>> memory reserves. This is quite tricky to do right, though. >> To use some portion of memory reserves is almost no effect in a so >> starvation scenario. I think the hungtask still will occur. it can >> not solve the problem primarily. > Granting an access to memory reserves is of course no full solution but > it raises chances for a forward progress. Other solutions would have to > guarantee that the memory reclaimed on behalf of the requester will be > given to the requester. Not an easy task > >>> Retry counters with the fail path have been proposed in the past and not >>> accepted. >> The above patch have been tested by runing the trinity. The question >> is fixed. Is there any reasonable reason oppose to the patch ? or it >> will bring in any side-effect. > Sure there is. Low order allocations have been traditionally non failing > and changing that behavior is a major obstacle because it opens up a > door to many bugs. I've tried to do something similar in the past and > there was a strong resistance against it. Believe me been there done > that... > hi, Michal Recently, I hit the same issue when run a OOM case of the LTP and ksm enable. [ 601.937145] Call trace: [ 601.939600] [] __switch_to+0x74/0x8c [ 601.944760] [] __schedule+0x23c/0x7bc [ 601.950007] [] schedule+0x3c/0x94 [ 601.954907] [] rwsem_down_write_failed+0x214/0x350 [ 601.961289] [] down_write+0x64/0x80 [ 601.966363] [] __ksm_exit+0x90/0x19c [ 601.971523] [] mmput+0x118/0x11c [ 601.976335] [] do_exit+0x2dc/0xa74 [ 601.981321] [] do_group_exit+0x4c/0xe4 [ 601.986656] [] get_signal+0x444/0x5e0 [ 601.991904] [] do_signal+0x1d8/0x450 [ 601.997065] [] do_notify_resume+0x70/0x78 The root case is that ksmd hold the read lock. and the lock is not released. scan_get_next_rmap_item down_read get_next_rmap_item alloc_rmap_item #ksmd will loop permanently. How do you see this kind of situation ? or let the issue alone. Thanks zhongjiang -- 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