From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2D06DF71 for ; Fri, 19 Jul 2024 03:55:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721361340; cv=none; b=hI0KBDW2bU/8Wylm3SFhB8E5N2V0WMQF2migIMSfurZ8UiUnZu7oZhWhMcj/+LvKynqE3YcEyn3+LnhhdkE7sE77YtJwb5U5TsQddwsYOtbbebRaNFqENLSklpKmzwzVxbjbz7fenj3m7zvKoc5XjIeuxqjHcGOTy83XsELaUZI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721361340; c=relaxed/simple; bh=kEj0kEpyv/SZuPTxZGlVX965wvoiV0y9G1NvmC+09LM=; h=Subject:To:CC:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=az+/r1iDSRLAyZeajE8wkvO8Uee0CzKpqBO1CpygTLkyy94/tuyzrpBcOIvut0/Vc67mPqd9SWYNhDBfQfLK74bqL7hZMPW9hfq/useWY4879kOW6BUMgGxyk5/vZB/MkvSc+G3VnoHuMwVRKVdNlx8Fg3Jby9OAqiz2BgvTkRY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.48]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4WQG1k6WStzQmDR; Fri, 19 Jul 2024 11:51:22 +0800 (CST) Received: from kwepemd200019.china.huawei.com (unknown [7.221.188.193]) by mail.maildlp.com (Postfix) with ESMTPS id 4C47B180087; Fri, 19 Jul 2024 11:55:28 +0800 (CST) Received: from [10.173.127.72] (10.173.127.72) by kwepemd200019.china.huawei.com (7.221.188.193) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 19 Jul 2024 11:55:27 +0800 Subject: Re: [PATCH] mm/memory-failure: fix VM_BUG_ON_PAGE(PagePoisoned(page)) when unpoison memory To: David Hildenbrand , Andrew Morton CC: , , References: <20240712064249.3882707-1-linmiaohe@huawei.com> <20240712140921.9aa90b18d22e67417d59dfc1@linux-foundation.org> <8fe349f9-d3d3-65ab-6045-da0bd19249ea@huawei.com> <00e18339-d911-4332-8732-e31bcecbf823@redhat.com> <5f8107e2-2b37-d899-f7f2-5a6093d8b089@huawei.com> From: Miaohe Lin Message-ID: Date: Fri, 19 Jul 2024 11:55:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemd200019.china.huawei.com (7.221.188.193) On 2024/7/18 13:15, David Hildenbrand wrote: > On 18.07.24 05:04, Miaohe Lin wrote: >> On 2024/7/17 17:01, David Hildenbrand wrote: >>> On 16.07.24 04:34, Miaohe Lin wrote: >>>> On 2024/7/16 0:16, David Hildenbrand wrote: >>>>> On 15.07.24 08:23, Miaohe Lin wrote: >>>>>> On 2024/7/13 5:09, Andrew Morton wrote: >>>>>>> On Fri, 12 Jul 2024 14:42:49 +0800 Miaohe Lin wrote: >>>>>>> >>>>>>>> When I did memory failure tests recently, below panic occurs: >>>>>>>> >>>>>>>> page dumped because: VM_BUG_ON_PAGE(PagePoisoned(page)) >>>>>>>> kernel BUG at include/linux/page-flags.h:616! >>>>>>>> Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI >>>>>>>> CPU: 3 PID: 720 Comm: bash Not tainted 6.10.0-rc1-00195-g148743902568 #40 >>>>>>>> RIP: 0010:unpoison_memory+0x2f3/0x590 >>>>>>>> RSP: 0018:ffffa57fc8787d60 EFLAGS: 00000246 >>>>>>>> RAX: 0000000000000037 RBX: 0000000000000009 RCX: ffff9be25fcdc9c8 >>>>>>>> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff9be25fcdc9c0 >>>>>>>> RBP: 0000000000300000 R08: ffffffffb4956f88 R09: 0000000000009ffb >>>>>>>> R10: 0000000000000284 R11: ffffffffb4926fa0 R12: ffffe6b00c000000 >>>>>>>> R13: ffff9bdb453dfd00 R14: 0000000000000000 R15: fffffffffffffffe >>>>>>>> FS:  00007f08f04e4740(0000) GS:ffff9be25fcc0000(0000) knlGS:0000000000000000 >>>>>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>>>>> CR2: 0000564787a30410 CR3: 000000010d4e2000 CR4: 00000000000006f0 >>>>>>>> Call Trace: >>>>>>>>     >>>>>>>>     unpoison_memory+0x2f3/0x590 >>>>>>>>     simple_attr_write_xsigned.constprop.0.isra.0+0xb3/0x110 >>>>>>>>     debugfs_attr_write+0x42/0x60 >>>>>>>>     full_proxy_write+0x5b/0x80 >>>>>>>>     vfs_write+0xd5/0x540 >>>>>>>>     ksys_write+0x64/0xe0 >>>>>>>>     do_syscall_64+0xb9/0x1d0 >>>>>>>>     entry_SYSCALL_64_after_hwframe+0x77/0x7f >>>>>>>> RIP: 0033:0x7f08f0314887 >>>>>>>> RSP: 002b:00007ffece710078 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 >>>>>>>> RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f08f0314887 >>>>>>>> RDX: 0000000000000009 RSI: 0000564787a30410 RDI: 0000000000000001 >>>>>>>> RBP: 0000564787a30410 R08: 000000000000fefe R09: 000000007fffffff >>>>>>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000009 >>>>>>>> R13: 00007f08f041b780 R14: 00007f08f0417600 R15: 00007f08f0416a00 >>>>>>>>     >>>>>>>> Modules linked in: hwpoison_inject >>>>>>>> ---[ end trace 0000000000000000 ]--- >>>>>>>> RIP: 0010:unpoison_memory+0x2f3/0x590 >>>>>>>> RSP: 0018:ffffa57fc8787d60 EFLAGS: 00000246 >>>>>>>> RAX: 0000000000000037 RBX: 0000000000000009 RCX: ffff9be25fcdc9c8 >>>>>>>> RDX: 0000000000000000 RSI: 0000000000000027 RDI: ffff9be25fcdc9c0 >>>>>>>> RBP: 0000000000300000 R08: ffffffffb4956f88 R09: 0000000000009ffb >>>>>>>> R10: 0000000000000284 R11: ffffffffb4926fa0 R12: ffffe6b00c000000 >>>>>>>> R13: ffff9bdb453dfd00 R14: 0000000000000000 R15: fffffffffffffffe >>>>>>>> FS:  00007f08f04e4740(0000) GS:ffff9be25fcc0000(0000) knlGS:0000000000000000 >>>>>>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>>>>>>> CR2: 0000564787a30410 CR3: 000000010d4e2000 CR4: 00000000000006f0 >>>>>>>> Kernel panic - not syncing: Fatal exception >>>>>>>> Kernel Offset: 0x31c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) >>>>>>>> ---[ end Kernel panic - not syncing: Fatal exception ]--- >>>>>>>> >>>>>>>> The root cause is that unpoison_memory() tries to check the PG_HWPoison >>>>>>>> flags of an uninitialized page. So VM_BUG_ON_PAGE(PagePoisoned(page)) is >>>>>>>> triggered. >>>>>>> >>>>>>> I'm not seeing the call path.  Is this BUG happening via >>>>>>> >>>>>>> static __always_inline void __ClearPage##uname(struct page *page)    \ >>>>>>> {                                    \ >>>>>>>       VM_BUG_ON_PAGE(!Page##uname(page), page);            \ >>>>>>>       page->page_type |= PG_##lname;                    \ >>>>>>> } >>>>>>> >>>>>>> ? >>>>>>> >>>>>>> If so, where's the callsite? >>>>>> >>>>>> It is BUG on PF_ANY(): >>>>>> >>>>>> PAGEFLAG(HWPoison, hwpoison, PF_ANY) >>>>>> >>>>>> #define PF_ANY(page, enforce)    PF_POISONED_CHECK(page) >>>>>> >>>>>> #define PF_POISONED_CHECK(page) ({                    \ >>>>>>       VM_BUG_ON_PGFLAGS(PagePoisoned(page), page);        \ >>>>>>       page; }) >>>>>> >>>>>> #define    PAGE_POISON_PATTERN    -1l >>>>>> static inline int PagePoisoned(const struct page *page) >>>>>> { >>>>>>       return READ_ONCE(page->flags) == PAGE_POISON_PATTERN; >>>>>> } >>>>>> >>>>>> The offlined pages will have page->flags set to PAGE_POISON_PATTERN while pfn is still valid: >>>>>> >>>>>> offline_pages >>>>>>      remove_pfn_range_from_zone >>>>>>        page_init_poison >>>>>>          memset(page, PAGE_POISON_PATTERN, size); >>>>> >>>>> Worth noting that this happens after __offline_isolated_pages() marked the covering sections as offline. >>>>> >>>>> Are we missing a pfn_to_online_page() check somewhere, or are we racing with offlining code that marks the section offline? >>>> >>>> I was thinking about to use pfn_to_online_page() instead of pfn_to_page() in unpoison_memory() so we can get rid of offlined pages. >>>> But there're ZONE_DEVICE pages. They're not-onlined too. And unpoison_memory() should work for them. So we can't simply use >>>> pfn_to_online_page() in that. Or am I miss something? >>> >>> Right, pfn_to_online_page() does not detect ZONE_DEVICE. That has to be handled separately if pfn_to_online_page() would fail. >>> >>> ... which is what we do in memory_failure(): >>> >>> p = pfn_to_online_page(pfn); >>> if (!p) { >>>      if (pfn_valid(pfn)) { >>>          pgmap = get_dev_pagemap(pfn, NULL); >>>          put_ref_page(pfn, flags); >>>          if (pgmap) { >>>              ... >>>          } >>>      } >>>      ... >>> } >> >> Yup, this will be a good alternative. But will it be better to simply check PagePoisoned() instead? > > The memmap of offline memory sections shall not be touched, so .... don't touch it ;) > > Especially because that PagePoisoned() check is non-sensical without poisoining-during-memmap-init. You would still work with memory in offline sections. > > I think the code is even wrong in that regard: we allow for memory offlining to work with HWPoisoned pages, see __offline_isolated_pages(). Staring at unpoison_memory(), we might be putting these pages back to the buddy? Which is completely wrong. I agree with you. Thanks for detailed explanation. :) Thanks David. .