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9BBC5140390; Thu, 18 Jul 2024 11:04:39 +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; Thu, 18 Jul 2024 11:04:38 +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: Thu, 18 Jul 2024 11:04:38 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.173.127.72] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemd200019.china.huawei.com (7.221.188.193) X-Stat-Signature: y3afy8mpbonawo9arwkrqjdkpcfohex6 X-Rspamd-Queue-Id: DC91E1C0023 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1721271883-658753 X-HE-Meta: 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 yffXU+AM YUvuaB+PGlBOYMDRm1BFrIaYfzTm+Z9PMSzdv4YpIn2UikTaYIEyRM6JXhsvpJAacoRzo2wsXxSBrV+f2iDUknu9sxFTvVIjc2J+6t6TE6Q8vxeFK47h+Ho9hJ5z7NrognJZYe9VbhcZQDsQE6VojckOnC9o7R3fmEFLJBp5slAR3pKh4ZEPN9AFLhIzg1GdjxyYn5WM6L3z9+p8Jxq5je+sQTXWvd4jYXQ9t+s4f9iK0ERi1/ySJ+/6ed3KJ7qqUSS76oY9iAf82pKTj45+sqEjy6Y74bKokSuNohFOBjQvvatk= 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: List-Subscribe: List-Unsubscribe: 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? Thanks. .