Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753274AbdLNOGB (ORCPT ); Thu, 14 Dec 2017 09:06:01 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:57682 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752676AbdLNOF7 (ORCPT ); Thu, 14 Dec 2017 09:05:59 -0500 From: Anshuman Khandual To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, mhocko@suse.com Subject: [PATCH V3] mm/mprotect: Add a cond_resched() inside change_pmd_range() Date: Thu, 14 Dec 2017 19:35:51 +0530 X-Mailer: git-send-email 2.9.3 X-TM-AS-GCONF: 00 x-cbid: 17121414-0012-0000-0000-000005991BEC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17121414-0013-0000-0000-000019143860 Message-Id: <20171214140551.5794-1-khandual@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-12-14_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712140191 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3888 Lines: 86 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. [ 850.962530] INFO: rcu_sched detected stalls on CPUs/tasks: [ 850.962584] 154-....: (670 ticks this GP) idle=022/140000000000000/0 softirq=2825/2825 fqs=612 [ 850.962605] (detected by 955, t=6002 jiffies, g=4486, c=4485, q=90864) [ 850.962895] Sending NMI from CPU 955 to CPUs 154: [ 850.992667] NMI backtrace for cpu 154 [ 850.993069] CPU: 154 PID: 147071 Comm: workload Not tainted 4.15.0-rc3+ #3 [ 850.993258] NIP: c0000000000b3f64 LR: c0000000000b33d4 CTR: 000000000000aa18 [ 850.993503] REGS: 00000000a4b0fb44 TRAP: 0501 Not tainted (4.15.0-rc3+) [ 850.993707] MSR: 8000000000009033 CR: 22422082 XER: 00000000 [ 850.994386] CFAR: 00000000006cf8f0 SOFTE: 1 GPR00: 0010000000000000 c00003ef9b1cb8c0 c0000000010cc600 0000000000000000 GPR04: 8e0000018c32b200 40017b3858fd6e00 8e0000018c32b208 40017b3858fd6e00 GPR08: 8e0000018c32b210 40017b3858fd6e00 8e0000018c32b218 40017b3858fd6e00 GPR12: ffffffffffffffff c00000000fb25100 [ 850.995976] NIP [c0000000000b3f64] plpar_hcall9+0x44/0x7c [ 850.996174] LR [c0000000000b33d4] pSeries_lpar_flush_hash_range+0x384/0x420 [ 850.996401] Call Trace: [ 850.996600] [c00003ef9b1cb8c0] [c00003fa8fff7d40] 0xc00003fa8fff7d40 (unreliable) [ 850.996959] [c00003ef9b1cba40] [c0000000000688a8] flush_hash_range+0x48/0x100 [ 850.997261] [c00003ef9b1cba90] [c000000000071b14] __flush_tlb_pending+0x44/0xd0 [ 850.997600] [c00003ef9b1cbac0] [c000000000071fa8] hpte_need_flush+0x408/0x470 [ 850.997958] [c00003ef9b1cbb30] [c0000000002c646c] change_protection_range+0xaac/0xf10 [ 850.998180] [c00003ef9b1cbcb0] [c0000000002f2510] change_prot_numa+0x30/0xb0 [ 850.998502] [c00003ef9b1cbce0] [c00000000013a950] task_numa_work+0x2d0/0x3e0 [ 850.998816] [c00003ef9b1cbda0] [c00000000011ea30] task_work_run+0x130/0x190 [ 850.999121] [c00003ef9b1cbe00] [c00000000001bcd8] do_notify_resume+0x118/0x120 [ 850.999421] [c00003ef9b1cbe30] [c00000000000b744] ret_from_except_lite+0x70/0x74 [ 850.999716] Instruction dump: [ 850.999959] 60000000 f8810028 7ca42b78 7cc53378 7ce63b78 7d074378 7d284b78 7d495378 [ 851.000575] e9410060 e9610068 e9810070 44000022 <7d806378> e9810028 f88c0000 f8ac0008 Suggested-by: Nicholas Piggin Signed-off-by: Anshuman Khandual --- Changes in V3: - Enabled the scheduling point for THP backed pages and pmd holes Changes in V2: (https://patchwork.kernel.org/patch/10111863/) - Moved cond_resched() to change_pmd_range() as per Michal Hocko - Fixed commit message as appropriate Changes in V1: (https://patchwork.kernel.org/patch/10111445/) mm/mprotect.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index ec39f73..58b629b 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -166,7 +166,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, next = pmd_addr_end(addr, end); if (!is_swap_pmd(*pmd) && !pmd_trans_huge(*pmd) && !pmd_devmap(*pmd) && pmd_none_or_clear_bad(pmd)) - continue; + goto next; /* invoke the mmu notifier if the pmd is populated */ if (!mni_start) { @@ -188,7 +188,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, } /* huge pmd was handled */ - continue; + goto next; } } /* fall through, the trans huge pmd just split */ @@ -196,6 +196,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma, 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) -- 2.9.3