From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-516909-1519834300-2-16682651957439838247 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 0.249, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='uk', 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=arctest; t=1519834299; b=nuBwbUeAea0F3bnDX/ovV6F6ZeGx+mzVAY0y7Xr/rel33VB rx+QEpxT60fpFbli7jOCURWg21fZj4Vc6yfNH8hTgBFRC5Xo8cQ/h2m2Z6tMCh9t c5l5Znl2V8BA6eIqHe26YlVxSm+505pL6H3e+CiQxUyINoTHZGpu8pUuXpZWxZNg x/2YM00SK8c0djmPbodH/d9nNMq4JzDzEAATu9pHVN2L8VHReq+lYqE2k94hvSX3 053CTzVlFcGxTTsx557XAAw/ZCuPFg6fiBsjm/W9rJwBK0qn20Uf15XKLS8X5XaK TUzsTwGSjlhT1ay6bDBEwFkZAWHcrGrt7n6EPhg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:content-transfer-encoding :mime-version:from:to:cc:date:message-id:subject:in-reply-to :sender:list-id; s=arctest; t=1519834299; bh=qLMynzppgZVieDT6P3M NMaJzQlZYmpJ4HmWfVY/R7aU=; b=teOnpc3TZQaQmEuVcOuQ8fRGEpJRwMoK5e8 el78bWTiIE/Bww55HT/aliSblhoYhoOPDGPbbJN8yf3gPyTy8KxpWcifcpEECSvz Mn4rsRECeQ2Y4NE9J8uYLcpGi/NDGBz9o4Oh/5Z3eoVHKrCAw3us5oTsm3S9VPhc bMg5lkWH6RCXiSzFAZ6x43CcICN8SzdDpwdZtm0PLBdctqldLjYKY16TvrNu3QB1 yQ9EM4mJTWgVZVwnJqAdP/xU6Ala36A3HZwLRgsgFa/WD87CIC3kZHRlRXJ4NXeR ckfHTWQSefdPa9YxLfMBt7zW1J0KPfDtipI+F6mGD3CYf+SWGkA== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; 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-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=decadent.org.uk header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; 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-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=decadent.org.uk header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752602AbeB1QIc (ORCPT ); Wed, 28 Feb 2018 11:08:32 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34953 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934474AbeB1QI3 (ORCPT ); Wed, 28 Feb 2018 11:08:29 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Linus Torvalds" , "Nicholas Piggin" , "Anshuman Khandual" , "Michal Hocko" Date: Wed, 28 Feb 2018 15:20:18 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 170/254] mm/mprotect: add a cond_resched() inside change_pmd_range() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false 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: 3.16.55-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Anshuman Khandual commit 4991c09c7c812dba13ea9be79a68b4565bb1fa4e upstream. While testing on a large CPU system, detected the following RCU stall many times over the span of the workload. This problem is solved by adding a cond_resched() in the change_pmd_range() function. INFO: rcu_sched detected stalls on CPUs/tasks: 154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612 (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864) Sending NMI from CPU 955 to CPUs 154: NMI backtrace for cpu 154 CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3 NIP: c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18 REGS: 00000000a4b0fb44 TRAP: 0501 Not tainted (4.15.0-rc3+) MSR: 8000000000009033 CR: 22422082 XER: 00000000 CFAR: 00000000006cf8f0 SOFTE: 1 GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000 GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00 GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00 GPR12: ffffffffffffffff c00000000fb25100 NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420 Call Trace: flush_hash_range+0x48/0x100 __flush_tlb_pending+0x44/0xd0 hpte_need_flush+0x408/0x470 change_protection_range+0xaac/0xf10 change_prot_numa+0x30/0xb0 task_numa_work+0x2d0/0x3e0 task_work_run+0x130/0x190 do_notify_resume+0x118/0x120 ret_from_except_lite+0x70/0x74 Instruction dump: 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378 e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008 Link: http://lkml.kernel.org/r/20171214140551.5794-1-khandual@linux.vnet.ibm.com Signed-off-by: Anshuman Khandual Suggested-by: Nicholas Piggin Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- mm/mprotect.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -152,7 +152,7 @@ static inline unsigned long change_pmd_r next = pmd_addr_end(addr, end); if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd)) - continue; + goto next; /* invoke the mmu notifier if the pmd is populated */ if (!mni_start) { @@ -174,7 +174,7 @@ static inline unsigned long change_pmd_r } /* huge pmd was handled */ - continue; + goto next; } } /* fall through, the trans huge pmd just split */ @@ -182,6 +182,8 @@ static inline unsigned long change_pmd_r this_pages = change_pte_range(vma, pmd, addr, next, newprot, dirty_accountable, prot_numa); pages += this_pages; +next: + cond_resched(); } while (pmd++, addr = next, addr != end); if (mni_start)