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 4B6C2C433F5 for ; Tue, 12 Apr 2022 10:00:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B37236B007D; Tue, 12 Apr 2022 06:00:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AE6EB6B007E; Tue, 12 Apr 2022 06:00:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9AEB86B0080; Tue, 12 Apr 2022 06:00:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 8C60E6B007D for ; Tue, 12 Apr 2022 06:00:16 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 565C4247A4 for ; Tue, 12 Apr 2022 10:00:16 +0000 (UTC) X-FDA: 79347781632.05.0DEB1B4 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) by imf08.hostedemail.com (Postfix) with ESMTP id E71DC160002 for ; Tue, 12 Apr 2022 10:00:14 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R681e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=xuyu@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0V9uO8qO_1649757609; Received: from 30.225.28.172(mailfrom:xuyu@linux.alibaba.com fp:SMTPD_---0V9uO8qO_1649757609) by smtp.aliyun-inc.com(127.0.0.1); Tue, 12 Apr 2022 18:00:10 +0800 Message-ID: <649dae7f-8513-0484-6565-cc0167015ac2@linux.alibaba.com> Date: Tue, 12 Apr 2022 18:00:09 +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 From: Yu Xu 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> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 6nbhpgwpmzisip9nwj7569ak8ypsusem Authentication-Results: imf08.hostedemail.com; dkim=none; spf=pass (imf08.hostedemail.com: domain of xuyu@linux.alibaba.com designates 115.124.30.132 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: E71DC160002 X-HE-Tag: 1649757614-780895 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 5:45 PM, Yu Xu wrote: > 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(). If so, we just need to add a one-line condition in try_to_split_thp_page(). > >> +            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