From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (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 C590D1DFF7 for ; Mon, 5 Aug 2024 06:25:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722839124; cv=none; b=r9B1jcmTygSLQkynN6C0T9P9sHcJjcaXzLUKAC9bDDUmtIoIbpYXPybA8GHh/XD/II+zSwhdgPOh9Em5CbP9do4rRncj5KXvrCDYPXRkA1bbvwJoN+kEAM9vaeo4fiDI3QdIsRYYy6hlPWVcNvd9xeYv4cxZXgVQUdX76REGfXQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722839124; c=relaxed/simple; bh=YDghittTVl+AJyYN2LcKbeI8kB56RWne2ZVTQ286bC4=; h=Subject:To:CC:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=ZpX3oPNIIYAFq9uay/SlNVLcmFXfXbcYRAQJgFRWDW3I1i3oVqbTwjaknnIvqbAXdYEbc9cYQ4krVHljaW3E/ujZdjpnX0sgJzr35F4FBxiSUY0VW7AAvHCHtvP95kgRLjoAQ3zW+yJBLvjStQC7k8obic4mqU98GPRA2TbsXxY= 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=45.249.212.188 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 [172.19.162.254]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4WcmbG6hPszfZhn; Mon, 5 Aug 2024 14:23:22 +0800 (CST) Received: from kwepemd200019.china.huawei.com (unknown [7.221.188.193]) by mail.maildlp.com (Postfix) with ESMTPS id B9332180100; Mon, 5 Aug 2024 14:25:15 +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; Mon, 5 Aug 2024 14:25:15 +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: <0519bf4b-49aa-6b81-a041-362a171b2a5e@huawei.com> Date: Mon, 5 Aug 2024 14:25:14 +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: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemd200019.china.huawei.com (7.221.188.193) On 2024/8/2 4:24, David Hildenbrand wrote: > On 19.07.24 05:55, Miaohe Lin wrote: >> 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. > > So ... I assume there will be a new patch? :) I was just back from my two-weeks holidays. ;) I will try to send a new version when possible. Thanks. .