From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 4DE771CA84 for ; Fri, 18 Jul 2025 08:26:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752827213; cv=none; b=MXZOX5Cue8TgVWX48RSH40FR4qoGc3be65+65Iqf5bwCiF9n8UlK5azwNt1RWld8/v3SPuZ6AAzRAaHXZwAfKxp1pvwsfMFUWJ2+HWx8zBixaiEMWI4sxXJDp76anFi3AJyuupUlB59AyPNQUtZ6e5WVvi2YkqPREp3Ax4J/MJA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752827213; c=relaxed/simple; bh=EG6vCHcXTrC5kfFClUImkl1dN/zUL2RSO66sEXh4XPs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ME9DuqBNyOqKGXQbXSJFImhUBjuaqV++EBIu530Yxk01M5gjmoSPwk78F73pYgexO2fxMedAjXFQGeYwBXKIytSI90XlSsWfgbRGakaKowl4ycBKbBdetdCMIQZeAIOJsskFxZMz4fosLkapDxXm1fWBI4VEiaE9loBreIJnbhI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=JbmVmItM; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JbmVmItM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752827211; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=Fh+hMoH6LGA/IpwYhkQC4mry4srHsI8Wk6A7cPmtJNQ=; b=JbmVmItMBsniauVriGJxWak12wTyVuYvRToAhNxpDFm6TsKPxvUkEUClW/8B7FxLkJqqyb lgq65vJfWGcSgAlh3k84d8/W6wnnrgYVdCoNKeJqT7ksyCuHPvv6EChcIlaq/YQYMAnclz O2KqOAQlvl031IEHtJiQDdy7GGnG3Xc= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-286-RCfA7dP5M--TXxDRPvf8iA-1; Fri, 18 Jul 2025 04:26:49 -0400 X-MC-Unique: RCfA7dP5M--TXxDRPvf8iA-1 X-Mimecast-MFC-AGG-ID: RCfA7dP5M--TXxDRPvf8iA_1752827208 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4538f375e86so16697485e9.3 for ; Fri, 18 Jul 2025 01:26:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752827208; x=1753432008; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=Fh+hMoH6LGA/IpwYhkQC4mry4srHsI8Wk6A7cPmtJNQ=; b=asFecO/MuXypRzxdWcCBUCqp0cB8y9U8oId3LGBuvrfrOfvtfNcv4WjshPrz2imxZn Wdn0U+sd+wsnIFeUez2TRDg3VKmUQhrClZ6h4jFPTigV7yjzCmOB6RQuBMzGr+i+DtS1 kuqUub9cQWP6XW913qQoxDFxIDVTlKmpGbDIAnf+Qt3TXeHes04m7p/N36Jb5ksrBrCs oC24788PbvikfPqPafMLEhFhf6YoASKURDkaCDpzkq7/LCNZ7tq4u9UVlV2d/cE6HlAa LC++O6hEPIN7TpE7+BCujTLz7XftSdn+Ow74HSmMhhYpxJy21+fT5kiFqaLaEY6VeAtq REVA== X-Forwarded-Encrypted: i=1; AJvYcCVyr2JVZZZQG6i8piDV6nJMFaDkHY/oKCj6gUm1uAb29VmVmqp3gsD+a01Qj9eCxz4qF+S6Ef9HoMJKnKY=@vger.kernel.org X-Gm-Message-State: AOJu0YxHxP+3SaQhbxT0vrTDl4bx4ZVQg33tH4a85zJVsBx0SA1muN19 cGkAXumRB/YGe+VbCQQo49999L0KrOnsPGhS1qfy3HOYmlu+hXzf8mE5LENsq1lRHGo5UPo75au c5iOpaYeD78j9RtzSaT0LdJWR/K+2z3Bwkg69un/3PgFBu20ZJLgJqA89RxNDbpjWzw== X-Gm-Gg: ASbGnct20HukEnrgYrVBMX7NPB7rd+v39C5o9tdlsMt9YAV6ehATf1GxtrcgzQRF6Gy oluGx/aIIrVW+iLu+Z/7QC8l6bSvkheKVMABOJwYendZjNu11fiUUHdFJ7VubVqKyc3cwAERNW2 uNAcV06ZAdoaePuERjiyb5wjxtAZhqOW3+MJfdCO/4wd80vrQokXizVZB9GoHJpMlttPuqrwZcj mmxKHQAs/dsfgt71G7wV+Vg9bOMY0vLlq8rHUsyeORUceSFBlsdrDognceuUvBF2BExePXi/ALh 113IAkjikTsr6Nv+OcMKznp6OWxjEigQh9v0Od6UEDQqwXfCGcz8jAHnv7+VkSVJ90QkmiF38/2 C2qREfjqnsV/nuPPIH/RlNiwX6rumzuaNMni09tkHAivQqa2F6E9md0aj3XFwQF8fit0= X-Received: by 2002:a05:600c:a089:b0:442:e9eb:cba2 with SMTP id 5b1f17b1804b1-4562dfc0150mr115638895e9.0.1752827207884; Fri, 18 Jul 2025 01:26:47 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHD/3Ne58bEKVAFm6OxA4kILsajKRFE9VzvEFYW8WykrRXvnfSb8yGYzDQJezo8A49ZYr5JNw== X-Received: by 2002:a05:600c:a089:b0:442:e9eb:cba2 with SMTP id 5b1f17b1804b1-4562dfc0150mr115638255e9.0.1752827207273; Fri, 18 Jul 2025 01:26:47 -0700 (PDT) Received: from ?IPV6:2003:d8:2f43:8900:f364:1333:2a67:d49e? (p200300d82f438900f36413332a67d49e.dip0.t-ipconnect.de. [2003:d8:2f43:8900:f364:1333:2a67:d49e]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4563b75de26sm12969775e9.33.2025.07.18.01.26.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Jul 2025 01:26:46 -0700 (PDT) Message-ID: <9001b918-a08d-4b38-9737-b5d9949668be@redhat.com> Date: Fri, 18 Jul 2025 10:26:45 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 6/9] mm/memory: convert print_bad_pte() to print_bad_page_map() To: Demi Marie Obenour , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, xen-devel@lists.xenproject.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, Andrew Morton , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Jann Horn , Pedro Falcato , Hugh Dickins , Oscar Salvador , Lance Yang References: <20250717115212.1825089-1-david@redhat.com> <20250717115212.1825089-7-david@redhat.com> <30268c21-a907-43d9-ac12-f6215cd95d03@gmail.com> <62cc8974-ddad-44a0-9f7c-e8a75a53ff99@redhat.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 18.07.25 09:59, Demi Marie Obenour wrote: > On 7/18/25 03:44, David Hildenbrand wrote: >> On 18.07.25 00:06, Demi Marie Obenour wrote: >>> On 7/17/25 07:52, David Hildenbrand wrote: >>>> print_bad_pte() looks like something that should actually be a WARN >>>> or similar, but historically it apparently has proven to be useful to >>>> detect corruption of page tables even on production systems -- report >>>> the issue and keep the system running to make it easier to actually detect >>>> what is going wrong (e.g., multiple such messages might shed a light). >>>> >>>> As we want to unify vm_normal_page_*() handling for PTE/PMD/PUD, we'll have >>>> to take care of print_bad_pte() as well. >>>> >>>> Let's prepare for using print_bad_pte() also for non-PTEs by adjusting the >>>> implementation and renaming the function -- we'll rename it to what >>>> we actually print: bad (page) mappings. Maybe it should be called >>>> "print_bad_table_entry()"? We'll just call it "print_bad_page_map()" >>>> because the assumption is that we are dealing with some (previously) >>>> present page table entry that got corrupted in weird ways. >>>> >>>> Whether it is a PTE or something else will usually become obvious from the >>>> page table dump or from the dumped stack. If ever required in the future, >>>> we could pass the entry level type similar to "enum rmap_level". For now, >>>> let's keep it simple. >>>> >>>> To make the function a bit more readable, factor out the ratelimit check >>>> into is_bad_page_map_ratelimited() and place the dumping of page >>>> table content into __dump_bad_page_map_pgtable(). We'll now dump >>>> information from each level in a single line, and just stop the table >>>> walk once we hit something that is not a present page table. >>>> >>>> Use print_bad_page_map() in vm_normal_page_pmd() similar to how we do it >>>> for vm_normal_page(), now that we have a function that can handle it. >>>> >>>> The report will now look something like (dumping pgd to pmd values): >>>> >>>> [ 77.943408] BUG: Bad page map in process XXX entry:80000001233f5867 >>>> [ 77.944077] addr:00007fd84bb1c000 vm_flags:08100071 anon_vma: ... >>>> [ 77.945186] pgd:10a89f067 p4d:10a89f067 pud:10e5a2067 pmd:105327067 >>>> >>>> Not using pgdp_get(), because that does not work properly on some arm >>>> configs where pgd_t is an array. Note that we are dumping all levels >>>> even when levels are folded for simplicity. >>>> >>>> Signed-off-by: David Hildenbrand >>> >>> Should this still use a WARN? If the admin sets panic-on-warn they >>> have asked for "crash if anything goes wrong" and so that is what >>> they should get. Otherwise the system will still stay up. >> >> I assume you're comment is in context of the other proposal regarding >> panicking. > > Which one? I'm only subscribed to xen-devel and might have missed it. This one here: https://lkml.kernel.org/r/4e1b7d2d-ed54-4e0a-a0a4-906b14d9cd41@p183 -- Cheers, David / dhildenb