From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-659992-1519838838-2-8701672690319037059 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=1519838838; b=YK+7oOuEpa8NH0CAljqnGsj6CdYpCdQFnuRE926uEqUawNZ vDMR271gF5ZqME1fCxMZujZMQD9fTSGHzKBLZkS5DUtpPHrhQ2rElMODlfLw3wuH hiOzDMqGAfYZ3QVF2uuufj9auU3qtSrW+edSpjF3JqqiqQslzYLkHAoQoQyFTImi OGIadK5FbaPunteHYT9r/W7y8XA7arn0OvcT4iID2dahk1bE4ZqBe2Z3KU/XZwBl ge7mL4gFzZE0CYsgOA3QuUUyUKWgduTl+ong4HusfOCHeFkW++ewKHtdOkv8GDu5 RVBYJS9tCNE7wQhyPGyvA7IZqoGtYVyZude5UFw== 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=1519838838; bh=FZHj/2bFspll1XA9pvN wzuNPHgIdNifVT+zHCJAaWdk=; b=TgGPhGSXlmLo1bIVnR7cjc7o7iJVD2T9Ayb CoAMbZobFQA2suuQHHhMfowvdXIThi2zjx1ipJvC/4K5UmX4pLR2yZSGn6DTLCg2 03tkG7D6JPq6v7heZyyeaBVmgCv4gKUl/H78TDqNZqAtsxKumW4/F8J+akCPzH42 HtdD+5nKmzobAogevCbOst4BuW1JvtL46V7ctaLL7nTXF6kRng/RrA4D8jGoTt1i M5XIrGVLb8GtjRfv9xPvtEtpzG9RIAi32iE+WFn4BWlYFf/wlGwSxaNO3mhH6kTI VCffy3pDcpcY7ehx1CJ3l/2lZFYQ9qBhO84xYxEzKJXrYOnXSeQ== 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=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: 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=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 S932361AbeB1RZI (ORCPT ); Wed, 28 Feb 2018 12:25:08 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33284 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932612AbeB1PWP (ORCPT ); Wed, 28 Feb 2018 10:22:15 -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, "Michal Hocko" , "Linus Torvalds" , "Nicholas Piggin" , "Anshuman Khandual" Date: Wed, 28 Feb 2018 15:20:22 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 082/140] 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: 3.2.100-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 3.2: 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 @@ -92,13 +92,15 @@ static inline void change_pmd_range(stru if (next - addr != HPAGE_PMD_SIZE) split_huge_page_pmd(vma->vm_mm, pmd); else if (change_huge_pmd(vma, pmd, addr, newprot)) - continue; + goto next; /* fall through */ } if (pmd_none_or_clear_bad(pmd)) - continue; + goto next; change_pte_range(vma->vm_mm, pmd, addr, next, newprot, dirty_accountable); +next: + cond_resched(); } while (pmd++, addr = next, addr != end); }