From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E51DC04AB5 for ; Thu, 6 Jun 2019 17:30:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 482F32083D for ; Thu, 6 Jun 2019 17:30:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730153AbfFFRac (ORCPT ); Thu, 6 Jun 2019 13:30:32 -0400 Received: from swift.blarg.de ([138.201.185.127]:37802 "EHLO swift.blarg.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726924AbfFFRab (ORCPT ); Thu, 6 Jun 2019 13:30:31 -0400 X-Greylist: delayed 348 seconds by postgrey-1.27 at vger.kernel.org; Thu, 06 Jun 2019 13:30:30 EDT Received: by swift.blarg.de (Postfix, from userid 1000) id C92E14030F; Thu, 6 Jun 2019 19:24:40 +0200 (CEST) Date: Thu, 6 Jun 2019 19:24:40 +0200 From: Max Kellermann To: Justin Piszcz Cc: "Kirill A. Shutemov" , LKML Subject: Re: 5.1 kernel: khugepaged stuck at 100% Message-ID: <20190606172440.GA24838@swift.blarg.de> Mail-Followup-To: Justin Piszcz , "Kirill A. Shutemov" , LKML References: <002901d5064d$42355ea0$c6a01be0$@lucidpixels.com> <20190509111343.rvmy5noqlf4os3zk@box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/05/16 16:14, Justin Piszcz wrote: > Kernel: 5.1.2 > > $ sudo cat /proc/$(pidof khugepaged)/stack > [<0>] 0xffffffffffffffff > > $ perf top > > PerfTop: 3716 irqs/sec kernel:92.9% exact: 99.1% lost: 68/68 > drop: 0/0 [4000Hz cycles], (all, 12 CPUs) > ------------------------------------------------------------------------------- > > 47.53% [kernel] [k] compaction_alloc > 38.88% [kernel] [k] __pageblock_pfn_to_page > 6.68% [kernel] [k] nmi > 0.58% [kernel] [k] __list_del_entry_valid > 0.48% [kernel] [k] format_decode > 0.39% [kernel] [k] __rb_insert_augmented > 0.25% libdbus-1.so.3.19.9 [.] _dbus_string_hex_decode > 0.24% [kernel] [k] entry_SYSCALL_64_after_hwframe > 0.20% perf [.] rb_next > 0.19% perf [.] __symbols__insert I have the same problem (kernel 5.1.7), but over here, it's a PHP process, not khugepaged, which is looping inside compaction_alloc. This is from "perf report": 100.00% 0.00% php-cgi7.0 php-cgi7.0 [.] 0x000055d0e88bc5ee | ---0x55d0e88bc5ee page_fault __do_page_fault handle_mm_fault __handle_mm_fault do_huge_pmd_anonymous_page __alloc_pages_nodemask __alloc_pages_slowpath __alloc_pages_direct_compact try_to_compact_pages compact_zone_order compact_zone migrate_pages compaction_alloc | |--24.43%--__pageblock_pfn_to_page | --2.22%--_cond_resched | --0.89%--rcu_all_qs ftrace: <...>-263514 [012] .... 109004.793009: rcu_all_qs <-_cond_resched <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793009: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793010: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: __pageblock_pfn_to_page <-compaction_alloc <...>-263514 [012] .... 109004.793011: _cond_resched <-compaction_alloc (Repeating this sequence over and over.) Nothing useful in /proc/263514/{stack,wchan,syscall}. What else can I do to collect more information to aid fix this? Max