From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 ECA4D2DC787 for ; Fri, 24 Oct 2025 15:43:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761320624; cv=none; b=srkE19qzQJZRGA47nK+ZcO9au+u7DsQVZNVpAO9Kg3FJGIQfkv/2bG2VCe9h9USjYuRilmNdyS77RbAyhrfS9Ita0eTaNYwV1DOkd/FADH+qMcWzlCeRISahs/dUAmohV9/m32UG+SGilwAiHuYHD+8lxvhdupcLM7mGKzzAoNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761320624; c=relaxed/simple; bh=DieyGbtLhyeH3gU3/2qoZqXvo8pdAbE9Yv5SiQ1wypI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TQc/3Kw3x7x1HcdWi1sXodWLv6mtrnsAVXm/1dzV6p4+DPABuTjhu78MOE2Z7sB7muEQ7JHNQfV77diM56Kwl4aSE4SfJhgZnl+iv3Y+lx4Glbn+TAFMlQY6Geflr0Pg5x4e1Rv3I3tybqtGUDB5rQ+hpJG1rXMKxx9za/ah9Y4= 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=ABdK/X8x; arc=none smtp.client-ip=170.10.129.124 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="ABdK/X8x" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761320621; 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=Ub0PNoE2B12NaRoLC+6G8KS0ixUn+UmUgZF/iuUYOng=; b=ABdK/X8xxeZ5Q1edV45rkY3WatH2vnTmDHneRxBArG27qVg9MLgFZjy26yhx+J3Mdz+XA/ bwulAqgoAhxpAkqMAMYdNO4htFGB/Zf4aoTXbrVb0TWXAztFCIIVS4yOcm62Q19zNR7nq2 qNutquO1lgtFrdme09JVPKAT55vbmXk= 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-339-x5_USaeTO36ijRk3ceO8Rw-1; Fri, 24 Oct 2025 11:43:40 -0400 X-MC-Unique: x5_USaeTO36ijRk3ceO8Rw-1 X-Mimecast-MFC-AGG-ID: x5_USaeTO36ijRk3ceO8Rw_1761320619 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-47113dfdd20so9129925e9.1 for ; Fri, 24 Oct 2025 08:43:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1761320619; x=1761925419; h=content-transfer-encoding:in-reply-to: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=Ub0PNoE2B12NaRoLC+6G8KS0ixUn+UmUgZF/iuUYOng=; b=EpvzmoX/zp/+46X9qt8vkyHLy4ZQ0aZf/EGx9Sy3DtoJK4bQEAkAycll4IFDZMnrHI 3Tl6jjxa8Bo6ZSP4L5+lOWL6gR2kZKkG33oBBfbSV1UkkCicD6wOqFQ0JFaVNKTR0hth mykHLw/2dyiID8GyC1iF3ssEKRYQ4GQx78FLoRKaB3mGxAQRgHbWb77FskHXEiIwaf4R gD7rCv7uCNaCD61JPj17Oxuesh5MpZ0aj2ui0WJz/zNHlJ3ha3+MJglOzWguKbZAKt2O ls8YCGhSq1mFeYG1GACAJqyslpXWcmIwTXKvLILEL/jCb/FbwKgstpYvqHmNe/kYL1Tn uGUw== X-Forwarded-Encrypted: i=1; AJvYcCXs3QwGkzptVAfl1t5D7PdQ+UKvZe62Nqft2i0btgehnk3aIezcAdhktmTpYlwNn3Vu7CYRzPptin7mzlbP@vger.kernel.org X-Gm-Message-State: AOJu0YxCpqdlwRykhOUG36qcQAPscWb6wjMgZ2lUxkt1p0QBPFvqXHXy eW9epN0VQcOJYAjFVzFYH9XX63ct/nTcgpJyeZuDaQGmQnvxfNV4Ji188Jb8lImCWiFAZHJ/xZf Xl6hng4MeRJb2h0uXVA/DRyjA9MmH+JEfP7RmwVMdeMIbgrh1NkJnrqLDILiwD/0su98= X-Gm-Gg: ASbGncu0KK2cs1P5qPWda2/KXFe59EUwdfhJeFFeDj3PuJUR52bysNgC4YEkzNmSgGN zraBD77WqA5HqEGBwVFDocGjpKyLOMBD511rMC/Vzuv+pgoa0eXQ0sHJsdlPuaIuSBLHpVDJSAH fyEwjpDKfi6ZW414dPKyMpUUZuUJDZfvfcHyzQaVXPmBS6M3NaxKLEc1B9HI8s6eabU4ZDoxOy/ Ae27A272TaE1xXBXYTO+BmIt2zUKmPjcF+j0DlebyYum4P//SfhJR/2k6eqwfmrrw1pO0rbxFmd 8q9vxjFnfexhGLOMBpX0mfnE469Pv11zDG3pqSNIDHRWea0/bdJF5KHI3udalG/SLNDXiRf/ND5 9hxnQT4oU4IitiTFGREsYVzBNrJVBvg0h/XcYEmAZl7kX2ObPA9xi/rd9KMEmD0Bx0KCSBWc/Kb /l6liMna2Wj6TIXgkjGyz/LrZBX6o= X-Received: by 2002:a05:600d:828d:b0:475:c5e7:e580 with SMTP id 5b1f17b1804b1-475c5e7e633mr67896345e9.32.1761320619248; Fri, 24 Oct 2025 08:43:39 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGcsWO+ZM/PYY8bptlnJAedXpz/Rg2rCmnppXlQBSMH+PbqY3P4FSmsB//MeHZgPtSXFS2jCA== X-Received: by 2002:a05:600d:828d:b0:475:c5e7:e580 with SMTP id 5b1f17b1804b1-475c5e7e633mr67896185e9.32.1761320618878; Fri, 24 Oct 2025 08:43:38 -0700 (PDT) Received: from ?IPV6:2003:d8:2f4e:3200:c99d:a38b:3f3a:d4b3? (p200300d82f4e3200c99da38b3f3ad4b3.dip0.t-ipconnect.de. [2003:d8:2f4e:3200:c99d:a38b:3f3a:d4b3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-475c4342946sm156957715e9.10.2025.10.24.08.43.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Oct 2025 08:43:38 -0700 (PDT) Message-ID: Date: Fri, 24 Oct 2025 17:43:36 +0200 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCHv2 2/2] mm/truncate: Unmap large folio on split failure To: Kiryl Shutsemau , Andrew Morton , Hugh Dickins , Matthew Wilcox , Alexander Viro , Christian Brauner Cc: Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Rik van Riel , Harry Yoo , Johannes Weiner , Shakeel Butt , Baolin Wang , "Darrick J. Wong" , Dave Chinner , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Kiryl Shutsemau References: <20251023093251.54146-1-kirill@shutemov.name> <20251023093251.54146-3-kirill@shutemov.name> 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 ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZoEEwEIAEQCGwMCF4ACGQEFCwkIBwICIgIG FQoJCAsCBBYCAwECHgcWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaJzangUJJlgIpAAKCRBN 3hD3AP+DWhAxD/9wcL0A+2rtaAmutaKTfxhTP0b4AAp1r/eLxjrbfbCCmh4pqzBhmSX/4z11 opn2KqcOsueRF1t2ENLOWzQu3Roiny2HOU7DajqB4dm1BVMaXQya5ae2ghzlJN9SIoopTWlR 0Af3hPj5E2PYvQhlcqeoehKlBo9rROJv/rjmr2x0yOM8qeTroH/ZzNlCtJ56AsE6Tvl+r7cW 3x7/Jq5WvWeudKrhFh7/yQ7eRvHCjd9bBrZTlgAfiHmX9AnCCPRPpNGNedV9Yty2Jnxhfmbv Pw37LA/jef8zlCDyUh2KCU1xVEOWqg15o1RtTyGV1nXV2O/mfuQJud5vIgzBvHhypc3p6VZJ lEf8YmT+Ol5P7SfCs5/uGdWUYQEMqOlg6w9R4Pe8d+mk8KGvfE9/zTwGg0nRgKqlQXrWRERv cuEwQbridlPAoQHrFWtwpgYMXx2TaZ3sihcIPo9uU5eBs0rf4mOERY75SK+Ekayv2ucTfjxr Kf014py2aoRJHuvy85ee/zIyLmve5hngZTTe3Wg3TInT9UTFzTPhItam6dZ1xqdTGHZYGU0O otRHcwLGt470grdiob6PfVTXoHlBvkWRadMhSuG4RORCDpq89vu5QralFNIf3EysNohoFy2A LYg2/D53xbU/aa4DDzBb5b1Rkg/udO1gZocVQWrDh6I2K3+cCs7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20251023093251.54146-3-kirill@shutemov.name> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 23.10.25 11:32, Kiryl Shutsemau wrote: > From: Kiryl Shutsemau > > Accesses within VMA, but beyond i_size rounded up to PAGE_SIZE are > supposed to generate SIGBUS. > > This behavior might not be respected on truncation. > > During truncation, the kernel splits a large folio in order to reclaim > memory. As a side effect, it unmaps the folio and destroys PMD mappings > of the folio. The folio will be refaulted as PTEs and SIGBUS semantics > are preserved. > > However, if the split fails, PMD mappings are preserved and the user > will not receive SIGBUS on any accesses within the PMD. > > Unmap the folio on split failure. It will lead to refault as PTEs and > preserve SIGBUS semantics. > > Signed-off-by: Kiryl Shutsemau > --- Thanks! Acked-by: David Hildenbrand -- Cheers David / dhildenb