From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-3308147-1523479445-2-12834279128968362158 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, MAILING_LIST_MULTI -1, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=fm2; t= 1523479444; b=DKo8UOZCQ28YZkLAEsimYvnas2qaO1gwTYFYbEsK5vMTWITFtl BNqOEwxTnjNhqKGsH0nAkWOMaUL0S1FIN0zLakNF64xmFHvuhcw/Varyhc7Oyxve 2ocKt7a6zn8x/yYvvgogSrjNm2FjVs2mcD6RBV3TlBK4LkjUkn48EyAkrWW1AJEU JSz7gjNjVzDYwyd/SLsS6Cd61jlFplpI8I/vOXAV03WRg/53qBdB67ZvAkra+fUu KO5KWx1vjJ937Tz13UFSQraK5mzWKX+r7tDVhaXPMiAyqAiCKW3ExF+ZFbA5gyrD 7Etm54QVw9kto5Oj3Ux/sDpO/QaOju0mhmoQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=fm2; t=1523479444; bh=oa5ck88G2xhW2AAqDPtdg5tVT6wDUx P8QJhQuB+5q10=; b=cJIP7VFvz0Lq7lb3U1sVyikAhbUmDoLEFpeJCaO3LPpmU2 qFVo2XaGlfr4CUELWtIKOJ0+q9NC8p388+Y0yTl+T8ZxbT+cyZnio44yQSz1B96c VjO0Ytns9gP7xKedf7xERx82JeA45DUerhW2+x314uc7bds8cj9P0QN2L8/B4Zk/ P9kTiZm1USnjro7FRjCgV9mIWNhi7mfEabAhmSbUAdZzXOtu0HfEDkN3G5DLT+ua PzUGVfNfj8ZsMw2dD3UGiRR5l/wivj1OqhJ6206/b4fWz4352R2jMGqV9rzCCS7D Fd/FsqXLxKcf8va1mdrbgtl4pERv1ZW8MpUvkvzg== ARC-Authentication-Results: i=1; mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 Authentication-Results: mx1.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-cm=none score=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean X-CM-Envelope: MS4wfDlAHdYdvBPAUNeqBiALD7kYMIX/jg2On4SkxiGYEt9mOJnJBp0JRK13kVqMagR7CdvIR/0kxK9/ff7lX/KXl+IK9hXZlbVfVPuycZ8naN3yR+RQnpR7 CZvTclWpti6j/ibhDd6etswY8vMGL1zLuCkz5KsM1wQbFoJnoBDmwRt9KbjMYmVNyH7mp7YpcoO4+TUypiCHiWYDRg1AaeJmHhE6sNW2YBaxnqpUuRmrPwrr X-CM-Analysis: v=2.3 cv=WaUilXpX c=1 sm=1 tr=0 a=UK1r566ZdBxH71SXbqIOeA==:117 a=UK1r566ZdBxH71SXbqIOeA==:17 a=IkcTkHD0fZMA:10 a=Kd1tUaAdevIA:10 a=JfrnYn6hAAAA:8 a=20KFwNOVAAAA:8 a=R_Myd5XaAAAA:8 a=Z4Rwk6OoAAAA:8 a=VwQbUJbxAAAA:8 a=yMhMjlubAAAA:8 a=ag1SF4gXAAAA:8 a=Q85a5QUVxAGcZ4WZ4qcA:9 a=QEXdDO2ut3YA:10 a=1CNFftbPRP8L7MoqJWF3:22 a=L2g4Dz8VuBQ37YGmWQah:22 a=HkZW87K1Qel5hWWM3VKY:22 a=AjGcO6oz07-iQ99wixmX:22 a=Yupwre4RP9_Eg_Bd0iYG:22 X-ME-CMScore: 0 X-ME-CMCategory: none Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752406AbeDKUoB (ORCPT ); Wed, 11 Apr 2018 16:44:01 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59278 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755860AbeDKSrX (ORCPT ); Wed, 11 Apr 2018 14:47:23 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , "Peter Zijlstra (Intel)" , Rik van Riel , Mel Gorman , Linus Torvalds , Thomas Gleixner , Ingo Molnar , Sasha Levin Subject: [PATCH 4.4 062/190] sched/numa: Use down_read_trylock() for the mmap_sem Date: Wed, 11 Apr 2018 20:35:08 +0200 Message-Id: <20180411183553.939186174@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180411183550.114495991@linuxfoundation.org> References: <20180411183550.114495991@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vlastimil Babka [ Upstream commit 8655d5497735b288f8a9b458bd22e7d1bf95bb61 ] A customer has reported a soft-lockup when running an intensive memory stress test, where the trace on multiple CPU's looks like this: RIP: 0010:[] [] native_queued_spin_lock_slowpath+0x10e/0x190 ... Call Trace: [] queued_spin_lock_slowpath+0x7/0xa [] change_protection_range+0x3b1/0x930 [] change_prot_numa+0x18/0x30 [] task_numa_work+0x1fe/0x310 [] task_work_run+0x72/0x90 Further investigation showed that the lock contention here is pmd_lock(). The task_numa_work() function makes sure that only one thread is let to perform the work in a single scan period (via cmpxchg), but if there's a thread with mmap_sem locked for writing for several periods, multiple threads in task_numa_work() can build up a convoy waiting for mmap_sem for read and then all get unblocked at once. This patch changes the down_read() to the trylock version, which prevents the build up. For a workload experiencing mmap_sem contention, it's probably better to postpone the NUMA balancing work anyway. This seems to have fixed the soft lockups involving pmd_lock(), which is in line with the convoy theory. Signed-off-by: Vlastimil Babka Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rik van Riel Acked-by: Mel Gorman Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170515131316.21909-1-vbabka@suse.cz Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- kernel/sched/fair.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2223,7 +2223,8 @@ void task_numa_work(struct callback_head return; - down_read(&mm->mmap_sem); + if (!down_read_trylock(&mm->mmap_sem)) + return; vma = find_vma(mm, start); if (!vma) { reset_ptenuma_scan(p);