From patchwork Tue Oct 13 14:44:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oscar Salvador X-Patchwork-Id: 11835727 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 704DF76EC for ; Tue, 13 Oct 2020 18:11:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C14A224880 for ; Tue, 13 Oct 2020 14:43:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C14A224880 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5627C6B0062; Tue, 13 Oct 2020 10:43:39 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 516F46B0068; Tue, 13 Oct 2020 10:43:39 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 42E386B006C; Tue, 13 Oct 2020 10:43:39 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id 346D96B0062 for ; Tue, 13 Oct 2020 10:43:39 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 6F8EA3624 for ; Tue, 13 Oct 2020 14:43:37 +0000 (UTC) X-FDA: 77367170874.16.bat77_4c11a5127204 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id E06E7100688A8 for ; Tue, 13 Oct 2020 14:43:36 +0000 (UTC) X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,osalvador@suse.de,,RULES_HIT:30012:30029:30054:30056:30070:30091,0,RBL:195.135.220.15:@suse.de:.lbl8.mailshell.net-64.100.201.201 62.2.6.2;04y8md31u3e4fr16otoe8r3tf5mx8opb9mqjpbkdiko3unbdu4wsiw7cos55ksz.wdm5wsmctochigb3m4aew7jhi3jinnstxrzsodoykuj91e98owbmm3q7kab3c75.n-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:19,LUA_SUMMARY:none X-HE-Tag: bat77_4c11a5127204 X-Filterd-Recvd-Size: 6160 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Tue, 13 Oct 2020 14:43:35 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 35DAFB19A; Tue, 13 Oct 2020 14:43:34 +0000 (UTC) From: Oscar Salvador To: n-horiguchi@ah.jp.nec.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador , Naoya Horiguchi Subject: [PATCH v5 2/4] mm,hwpoison: take free pages off the buddy freelists Date: Tue, 13 Oct 2020 16:44:45 +0200 Message-Id: <20201013144447.6706-3-osalvador@suse.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201013144447.6706-1-osalvador@suse.de> References: <20201013144447.6706-1-osalvador@suse.de> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The crux of the matter is that historically we left poisoned pages in the buddy system because we have some checks in place when allocating a page that are gatekeeper for poisoned pages. Unfortunately, we do have other users (e.g: compaction [1]) that scan buddy freelists and try to get a page from there without checking whether the page is HWPoison. As I stated already, I think it is fundamentally wrong to keep HWPoison pages within the buddy systems, checks in place or not. Let us fix this the same way we did for soft_offline [2], taking the page off the buddy freelist so it is completely unreachable. Note that this is fairly simple to trigger, as we only need to poison free buddy pages (madvise MADV_HWPOISON) and then run some sort of memory stress system. Just for a matter of reference, I put a dump_page() in compaction_alloc() to trigger for HWPoison patches: kernel: page:0000000012b2982b refcount:1 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1d5db kernel: flags: 0xfffffc0800000(hwpoison) kernel: raw: 000fffffc0800000 ffffea00007573c8 ffffc90000857de0 0000000000000000 kernel: raw: 0000000000000001 0000000000000000 00000001ffffffff 0000000000000000 kernel: page dumped because: compaction_alloc kernel: CPU: 4 PID: 123 Comm: kcompactd0 Tainted: G E 5.9.0-rc2-mm1-1-default+ #5 kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 kernel: Call Trace: kernel: dump_stack+0x6d/0x8b kernel: compaction_alloc+0xb2/0xc0 kernel: migrate_pages+0x2a6/0x12a0 kernel: ? isolate_freepages+0xc80/0xc80 kernel: ? __ClearPageMovable+0xb0/0xb0 kernel: compact_zone+0x5eb/0x11c0 kernel: ? finish_task_switch+0x74/0x300 kernel: ? lock_timer_base+0xa8/0x170 kernel: proactive_compact_node+0x89/0xf0 kernel: ? kcompactd+0x2d0/0x3a0 kernel: kcompactd+0x2d0/0x3a0 kernel: ? finish_wait+0x80/0x80 kernel: ? kcompactd_do_work+0x350/0x350 kernel: kthread+0x118/0x130 kernel: ? kthread_associate_blkcg+0xa0/0xa0 kernel: ret_from_fork+0x22/0x30 After that, if e.g: a process faults in the page, it will get killed unexpectedly. Fix it by containing the page immediatelly. Besides that, two more changes can be noticed: * MF_DELAYED no longer suits as we are fixing the issue by containing the page immediately, so it does no longer rely on the allocation-time checks to stop HWPoison to be handed over. gain unless it is unpoisoned, so we fixed the situation. Because of that, let us use MF_RECOVERED from now on. * The second block that handles PageBuddy pages is no longer needed: We call shake_page and then check whether the page is Buddy because shake_page calls drain_all_pages, which sends pcp-pages back to the buddy freelists, so we could have a chance to handle free pages. Currently, get_hwpoison_page already calls drain_all_pages, and we call get_hwpoison_page right before coming here, so we should be on the safe side. [1] https://lore.kernel.org/linux-mm/20190826104144.GA7849@linux/T/#u [2] https://patchwork.kernel.org/cover/11792607/ Signed-off-by: Oscar Salvador Acked-by: Naoya Horiguchi Acked-by: Vlastimil Babka --- mm/memory-failure.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index e2f12410c594..181bed890c16 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1341,6 +1341,7 @@ int memory_failure(unsigned long pfn, int flags) struct dev_pagemap *pgmap; int res; unsigned long page_flags; + bool retry = true; if (!sysctl_memory_failure_recovery) panic("Memory failure on page %lx", pfn); @@ -1358,6 +1359,7 @@ int memory_failure(unsigned long pfn, int flags) return -ENXIO; } +try_again: if (PageHuge(p)) return memory_failure_hugetlb(pfn, flags); if (TestSetPageHWPoison(p)) { @@ -1382,8 +1384,21 @@ int memory_failure(unsigned long pfn, int flags) */ if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) { if (is_free_buddy_page(p)) { - action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); - return 0; + if (take_page_off_buddy(p)) { + page_ref_inc(p); + res = MF_RECOVERED; + } else { + /* We lost the race, try again */ + if (retry) { + ClearPageHWPoison(p); + num_poisoned_pages_dec(); + retry = false; + goto try_again; + } + res = MF_FAILED; + } + action_result(pfn, MF_MSG_BUDDY, res); + return res == MF_RECOVERED ? 0 : -EBUSY; } else { action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED); return -EBUSY; @@ -1407,14 +1422,6 @@ int memory_failure(unsigned long pfn, int flags) * walked by the page reclaim code, however that's not a big loss. */ shake_page(p, 0); - /* shake_page could have turned it free. */ - if (!PageLRU(p) && is_free_buddy_page(p)) { - if (flags & MF_COUNT_INCREASED) - action_result(pfn, MF_MSG_BUDDY, MF_DELAYED); - else - action_result(pfn, MF_MSG_BUDDY_2ND, MF_DELAYED); - return 0; - } lock_page(p);