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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53054C433EF for ; Tue, 12 Apr 2022 09:45:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D92CD6B007E; Tue, 12 Apr 2022 05:45:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D411D6B0080; Tue, 12 Apr 2022 05:45:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C2FBE6B0081; Tue, 12 Apr 2022 05:45:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0254.hostedemail.com [216.40.44.254]) by kanga.kvack.org (Postfix) with ESMTP id B530C6B007E for ; Tue, 12 Apr 2022 05:45:34 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 717D4A75BA for ; Tue, 12 Apr 2022 09:45:34 +0000 (UTC) X-FDA: 79347744588.22.D969BB4 Received: from out30-56.freemail.mail.aliyun.com (out30-56.freemail.mail.aliyun.com [115.124.30.56]) by imf18.hostedemail.com (Postfix) with ESMTP id 59BBA1C0008 for ; Tue, 12 Apr 2022 09:45:32 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R121e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xuyu@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0V9uO3nF_1649756729; Received: from 30.225.28.172(mailfrom:xuyu@linux.alibaba.com fp:SMTPD_---0V9uO3nF_1649756729) by smtp.aliyun-inc.com(127.0.0.1); Tue, 12 Apr 2022 17:45:30 +0800 Message-ID: Date: Tue, 12 Apr 2022 17:45:28 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] mm/memory-failure.c: bail out early if huge zero page Content-Language: en-US To: Naoya Horiguchi , Miaohe Lin Cc: akpm@linux-foundation.org, Linux-MM , Naoya Horiguchi References: <49273e6688d7571756603dac996692a15f245d58.1649603963.git.xuyu@linux.alibaba.com> <8f06b79b-aeff-3479-a3cc-c0a649dc770b@huawei.com> <20220412090907.GA350357@u2004> From: Yu Xu In-Reply-To: <20220412090907.GA350357@u2004> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: ciaz6kiddpjfoa85hiqtafxacuxheuif Authentication-Results: imf18.hostedemail.com; dkim=none; spf=pass (imf18.hostedemail.com: domain of xuyu@linux.alibaba.com designates 115.124.30.56 as permitted sender) smtp.mailfrom=xuyu@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 59BBA1C0008 X-HE-Tag: 1649756732-86969 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: On 4/12/22 5:09 PM, Naoya Horiguchi wrote: > On Mon, Apr 11, 2022 at 10:18:26AM +0800, Miaohe Lin wrote: >> On 2022/4/10 23:22, Xu Yu wrote: >>> Kernel panic when injecting memory_failure for the global huge_zero_page, >>> when CONFIG_DEBUG_VM is enabled, as follows. >>> >>> [ 5.582720] Injecting memory failure for pfn 0x109ff9 at process virtual address 0x20ff9000 >>> [ 5.583786] page:00000000fb053fc3 refcount:2 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x109e00 >>> [ 5.584900] head:00000000fb053fc3 order:9 compound_mapcount:0 compound_pincount:0 >>> [ 5.585796] flags: 0x17fffc000010001(locked|head|node=0|zone=2|lastcpupid=0x1ffff) >>> [ 5.586712] raw: 017fffc000010001 0000000000000000 dead000000000122 0000000000000000 >>> [ 5.587640] raw: 0000000000000000 0000000000000000 00000002ffffffff 0000000000000000 >>> [ 5.588565] page dumped because: VM_BUG_ON_PAGE(is_huge_zero_page(head)) >>> [ 5.589398] ------------[ cut here ]------------ >>> [ 5.589952] kernel BUG at mm/huge_memory.c:2499! >>> [ 5.590516] invalid opcode: 0000 [#1] PREEMPT SMP PTI >>> [ 5.591120] CPU: 6 PID: 553 Comm: split_bug Not tainted 5.18.0-rc1+ #11 >>> [ 5.591904] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 3288b3c 04/01/2014 >>> [ 5.592817] RIP: 0010:split_huge_page_to_list+0x66a/0x880 >>> [ 5.593469] Code: 84 9b fb ff ff 48 8b 7c 24 08 31 f6 e8 9f 5d 2a 00 b8 b8 02 00 00 e9 e8 fb ff ff 48 c7 c6 e8 47 3c 82 4c b >>> [ 5.595806] RSP: 0018:ffffc90000dcbdf8 EFLAGS: 00010246 >>> [ 5.596434] RAX: 000000000000003c RBX: 0000000000000001 RCX: 0000000000000000 >>> [ 5.597322] RDX: 0000000000000000 RSI: ffffffff823e4c4f RDI: 00000000ffffffff >>> [ 5.598162] RBP: ffff88843fffdb40 R08: 0000000000000000 R09: 00000000fffeffff >>> [ 5.598999] R10: ffffc90000dcbc48 R11: ffffffff82d68448 R12: ffffea0004278000 >>> [ 5.599849] R13: ffffffff823c6203 R14: 0000000000109ff9 R15: ffffea000427fe40 >>> [ 5.600693] FS: 00007fc375a26740(0000) GS:ffff88842fd80000(0000) knlGS:0000000000000000 >>> [ 5.601640] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> [ 5.602304] CR2: 00007fc3757c9290 CR3: 0000000102174006 CR4: 00000000003706e0 >>> [ 5.603139] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> [ 5.603977] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>> [ 5.604806] Call Trace: >>> [ 5.605101] >>> [ 5.605357] ? __irq_work_queue_local+0x39/0x70 >>> [ 5.605904] try_to_split_thp_page+0x3a/0x130 >>> [ 5.606430] memory_failure+0x128/0x800 >>> [ 5.606888] madvise_inject_error.cold+0x8b/0xa1 >>> [ 5.607444] __x64_sys_madvise+0x54/0x60 >>> [ 5.607915] do_syscall_64+0x35/0x80 >>> [ 5.608347] entry_SYSCALL_64_after_hwframe+0x44/0xae >>> [ 5.608949] RIP: 0033:0x7fc3754f8bf9 >>> [ 5.609374] Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 8 >>> [ 5.611554] RSP: 002b:00007ffeda93a1d8 EFLAGS: 00000217 ORIG_RAX: 000000000000001c >>> [ 5.612441] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc3754f8bf9 >>> [ 5.613269] RDX: 0000000000000064 RSI: 0000000000003000 RDI: 0000000020ff9000 >>> [ 5.614108] RBP: 00007ffeda93a200 R08: 0000000000000000 R09: 0000000000000000 >>> [ 5.614946] R10: 00000000ffffffff R11: 0000000000000217 R12: 0000000000400490 >>> [ 5.615787] R13: 00007ffeda93a2e0 R14: 0000000000000000 R15: 0000000000000000 >>> [ 5.616626] >>> >> >> Thanks for the report and the patch! >> >> I remember I and Naoya discussed the try_to_split_thp_page in memory_failure might come >> across non-lru movable compound page and huge_zero_page. We fixed the non-lru movable >> compound page case but conclude huge_zero_page won't reach here due to the HWPoisonHandlable() >> check. But we missed the MF_COUNT_INCREASED case where HWPoisonHandlable() is skipped. >> >>> In fact, huge_zero_page is unhandlable currently in either soft offline >>> or memory failure injection. With CONFIG_DEBUG_VM disabled, >>> huge_zero_page is bailed out when checking HWPoisonHandlable() in >>> get_any_page(), or checking page mapping in split_huge_page_to_list(). >>> >>> This makes huge_zero_page bail out early in madvise_inject_error(), and >>> panic above won't happen again. >> >> It seems this issue is expected to happen only in madvise_inject_error case because >> MF_COUNT_INCREASED is only set here. So this fix should do the right thing. But I >> don't know whether bail out early for huge_zero_page is suitable. >> >> Hi Naoya, what do you think? > > Thank you for reporting. > > ... > >>> @@ -1087,12 +1087,21 @@ static int madvise_inject_error(int behavior, >>> return ret; >>> pfn = page_to_pfn(page); >>> >>> + head = compound_head(page); >>> + if (unlikely(is_huge_zero_page(head))) { >>> + pr_warn("Unhandlable attempt to %s pfn %#lx at process virtual address %#lx\n", >>> + behavior == MADV_SOFT_OFFLINE ? "soft offline" : >>> + "inject memory failure for", >>> + pfn, start); >>> + return -EINVAL; >>> + } > > This check is about the detail of error handling, so I feel it desirable to > do this in memory_failure(). And memory errors on huge zero page is the > real scenario, so it seems to me better to make this case injectable rather > than EINVAL. > > How about checking is_huge_zero_page() before try_to_split_thp_page()? > The result should be consistent with the results when called by other > memory_failure()'s callers like MCE handler and hard_offline_page_store(). Agree. thanks! > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 9b76222ee237..771fb4fc626c 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1852,6 +1852,12 @@ int memory_failure(unsigned long pfn, int flags) > } > > if (PageTransHuge(hpage)) { > + if (is_huge_zero_page(hpage)) { > + action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED); Should we use MF_MSG_UNSPLIT_THP instead of MF_MSG_KERNEL_HIGH_ORDER? And should we SetPageHasHWPoisoned(hpage) for huge zero page, since TestSetPageHWPoison(p) is done in the early part of memory_failure(). > + res = -EBUSY; > + goto unlock_mutex; > + } > + > /* > * The flag must be set after the refcount is bumped > * otherwise it may race with THP split. > > > Thanks, > Naoya Horiguchi -- Thanks, Yu