From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f45.google.com (mail-qg0-f45.google.com [209.85.192.45]) by kanga.kvack.org (Postfix) with ESMTP id DCABD6B0038 for ; Wed, 26 Aug 2015 11:35:21 -0400 (EDT) Received: by qgeh99 with SMTP id h99so69086409qge.0 for ; Wed, 26 Aug 2015 08:35:21 -0700 (PDT) Received: from www262.sakura.ne.jp (www262.sakura.ne.jp. [2001:e42:101:1:202:181:97:72]) by mx.google.com with ESMTPS id m75si22920878qki.120.2015.08.26.08.35.19 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 26 Aug 2015 08:35:20 -0700 (PDT) Subject: Re: [PATCH 2/2] android, lmk: Reverse the order of setting TIF_MEMDIE and sending SIGKILL. From: Tetsuo Handa References: <201508262117.FAH43726.tOFMVJSLQOFHFO@I-love.SAKURA.ne.jp> <201508262119.IHA93770.JOOtFHMSFLOQVF@I-love.SAKURA.ne.jp> In-Reply-To: <201508262119.IHA93770.JOOtFHMSFLOQVF@I-love.SAKURA.ne.jp> Message-Id: <201508270034.GEH35997.SFOMOVLFtOHFQJ@I-love.SAKURA.ne.jp> Date: Thu, 27 Aug 2015 00:34:47 +0900 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org List-ID: To: gregkh@linuxfoundation.org, arve@android.com, riandrews@android.com Cc: devel@driverdev.osuosl.org, linux-mm@kvack.org, mhocko@kernel.org, rientjes@google.com, hannes@cmpxchg.org Reposting updated version as it turned out that we can call do_send_sig_info() with task_lock held. ;-) ( http://marc.info/?l=linux-mm&m=144059948628905&w=2 ) Tetsuo Handa wrote: > Should selected_tasksize be added to rem even when TIF_MEMDIE was not set? Commit e1099a69a624 "android, lmk: avoid setting TIF_MEMDIE if process has already exited" changed not to add selected_tasksize to rem. But I noticed that rem is initialized to 0 and there is only one addition (i.e. rem += selected_tasksize means rem = selected_tasksize) since commit 7dc19d5affd7 "drivers: convert shrinkers to new count/scan API". I don't know what values we should return, but this patch restores pre commit e1099a69a624 because omitting a call to mark_oom_victim() due to race will not prevent from reclaiming memory because we already sent SIGKILL. ------------------------------------------------------------ >>From b7075abd3a1e903e88f1755c68adc017d2125b0d Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Thu, 27 Aug 2015 00:13:57 +0900 Subject: [PATCH 2/2] android, lmk: Send SIGKILL before setting TIF_MEMDIE. It was observed that setting TIF_MEMDIE before sending SIGKILL at oom_kill_process() allows memory reserves to be depleted by allocations which are not needed for terminating the OOM victim. This patch reverts commit 6bc2b856bb7c ("staging: android: lowmemorykiller: set TIF_MEMDIE before send kill sig"), for oom_kill_process() was updated to send SIGKILL before setting TIF_MEMDIE. Signed-off-by: Tetsuo Handa --- drivers/staging/android/lowmemorykiller.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c index d5d25e4..af604cf 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -156,26 +156,21 @@ next: } if (selected) { task_lock(selected); - if (!selected->mm) { - /* Already exited, cannot do mark_tsk_oom_victim() */ - task_unlock(selected); - goto out; - } + lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", + selected->pid, selected->comm, + selected_oom_score_adj, selected_tasksize); + send_sig(SIGKILL, selected, 0); /* * FIXME: lowmemorykiller shouldn't abuse global OOM killer * infrastructure. There is no real reason why the selected * task should have access to the memory reserves. */ - mark_oom_victim(selected); - lowmem_print(1, "send sigkill to %d (%s), adj %hd, size %d\n", - selected->pid, selected->comm, - selected_oom_score_adj, selected_tasksize); + if (selected->mm) + mark_oom_victim(selected); task_unlock(selected); lowmem_deathpending_timeout = jiffies + HZ; - send_sig(SIGKILL, selected, 0); rem += selected_tasksize; } -out: lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n", sc->nr_to_scan, sc->gfp_mask, rem); rcu_read_unlock(); -- 1.8.3.1 -- 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