From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 15BA2C4167B for ; Thu, 30 Nov 2023 13:44:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=KUCkdxD9THnRHOCCnDpklmlDd3SKeGxUNv4wsrCNuoI=; b=3vm+XPzg51xsZJ aKQEjeJ6O72KLl6G2NOBkr4SlITC9x0iI0DSrpj5Nw4u2oDj12J5Le6k5xlCVsjInigrbC/mMM+H9 r/6qUqar5cjwFS9PNrUWmghuPJhue6M+0UR4d0yLNgqafBp8sufQbgvmp+ILW4N6kti+/1vX+ftP9 c8riaR1UotCNEVeqHiO4JsO2FN2RfBLehcWkTAu9MfbQh1V9oSWmS/xM/a6OnXTLzQXjrxAQZgKFG agIYTj0T09iZRWoyyrGxFcwHdBXuviB/YVjwAiKf7stzT/96SNkHW44gE72gs8AJXhqwUsQaEfz2D fQPY9UB8MVz7JIhHQ1bQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1r8hKe-00Azx1-3C; Thu, 30 Nov 2023 13:43:57 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1r8hKc-00Azua-07 for linux-arm-kernel@lists.infradead.org; Thu, 30 Nov 2023 13:43:55 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1701351832; 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=vXLmPI3YKuWjybHeV+zzmSdSrTMtOftgtk5WyUqCzCo=; b=Wn797WPlnarnGqY3kdP5bzDr7ergVVpNM+FBxKF0d1NGYU4sPUwnJSPuqP/jbszbI2bW7C KDoQE0/CsdfOj8IBYYA0jnY013wUvWHqYKWuro0I36UV4Q8HHW6g/+AUCikOXkwWbx6VMv doI8rJnNnHSGUMtvq4e/L0yKQbFRHOw= Received: from mail-lj1-f197.google.com (mail-lj1-f197.google.com [209.85.208.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-54-PFEDVOLcPrKF8BFhFhDgcQ-1; Thu, 30 Nov 2023 08:43:51 -0500 X-MC-Unique: PFEDVOLcPrKF8BFhFhDgcQ-1 Received: by mail-lj1-f197.google.com with SMTP id 38308e7fff4ca-2c9c265c5bdso11000071fa.2 for ; Thu, 30 Nov 2023 05:43:51 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701351830; x=1701956630; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :references:cc:to:content-language:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=vXLmPI3YKuWjybHeV+zzmSdSrTMtOftgtk5WyUqCzCo=; b=ros8A/fYnEEb5yg6I7F+CPTKz3ha+GeIaR8ZuF4l+UgKiHr9stwq1vM5x5KMtxjV8R QfjN5ZuMsy8UaTcVe9BhKS7uRSAIbogJqLcoDtv2q5sIsN8ZQtGC+I69I+S7naOpggTG 1IaEXonJXKIn62MKTr4l7Am1O+VZAM48Ivm9ldY5GSfA0boTcE5fSp/SC2S9kOEKGJm5 2Ld7aO6bAi2UngNle6UqfijDlTPs9dzNpHLkPv3fmDxA59jcB+mD74DKVWoqOC0d9BHk qggA98FaEOQwbFtg3ekhbkr7OvysPDDaOtk3yE3qug4+H26GBt5AqTNiL9f14pbm3aXN opfQ== X-Gm-Message-State: AOJu0YxK7DrJBjplxj3FErjM9ZExHrnzmu1Ov7tXYroT+JPFtKaOQAEQ MIOnFjvC8Qhw+EyUoCWCySArCC7uJXztCj/6eI0eL0AGYx2Sa32FiqZSYXcZRP5WyHADYQnTKnT qK7Vnsz2A/KyzNb8jQE328YGxlJULd4mFeCk= X-Received: by 2002:a2e:9b4d:0:b0:2c9:b4c6:a7ff with SMTP id o13-20020a2e9b4d000000b002c9b4c6a7ffmr5098583ljj.40.1701351830306; Thu, 30 Nov 2023 05:43:50 -0800 (PST) X-Google-Smtp-Source: AGHT+IHNEah9uEWG0d1eEyNvSkC2EScna+/OIpBCKDONcD2fN4xZ88Wfm1ISF4DLZSarzZEBaM0Hyg== X-Received: by 2002:a2e:9b4d:0:b0:2c9:b4c6:a7ff with SMTP id o13-20020a2e9b4d000000b002c9b4c6a7ffmr5098553ljj.40.1701351829882; Thu, 30 Nov 2023 05:43:49 -0800 (PST) Received: from ?IPV6:2a09:80c0:192:0:5dac:bf3d:c41:c3e7? ([2a09:80c0:192:0:5dac:bf3d:c41:c3e7]) by smtp.gmail.com with ESMTPSA id s9-20020a05600c45c900b0040b4fca8620sm5777979wmo.37.2023.11.30.05.43.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Nov 2023 05:43:49 -0800 (PST) Message-ID: Date: Thu, 30 Nov 2023 14:43:48 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v2 19/27] mm: mprotect: Introduce PAGE_FAULT_ON_ACCESS for mprotect(PROT_MTE) To: Alexandru Elisei Cc: Hyesoo Yu , catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev, maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, arnd@arndb.de, akpm@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, mhiramat@kernel.org, rppt@kernel.org, hughd@google.com, pcc@google.com, steven.price@arm.com, anshuman.khandual@arm.com, vincenzo.frascino@arm.com, eugenis@google.com, kcc@google.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org References: <20231119165721.9849-1-alexandru.elisei@arm.com> <20231119165721.9849-20-alexandru.elisei@arm.com> <20231129092725.GD2988384@tiffany> <4e7a4054-092c-4e34-ae00-0105d7c9343c@redhat.com> From: David Hildenbrand 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/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz 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+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231130_054354_148846_B5276C55 X-CRM114-Status: GOOD ( 20.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 30.11.23 14:32, Alexandru Elisei wrote: > Hi, > > On Thu, Nov 30, 2023 at 01:49:34PM +0100, David Hildenbrand wrote: >>>>> + >>>>> +out_retry: >>>>> + put_page(page); >>>>> + if (vmf->flags & FAULT_FLAG_VMA_LOCK) >>>>> + vma_end_read(vma); >>>>> + if (fault_flag_allow_retry_first(vmf->flags)) { >>>>> + err = VM_FAULT_RETRY; >>>>> + } else { >>>>> + /* Replay the fault. */ >>>>> + err = 0; >>>> >>>> Hello! >>>> >>>> Unfortunately, if the page continues to be pinned, it seems like fault will continue to occur. >>>> I guess it makes system stability issue. (but I'm not familiar with that, so please let me know if I'm mistaken!) >>>> >>>> How about migrating the page when migration problem repeats. >>> >>> Yes, I had the same though in the previous iteration of the series, the >>> page was migrated out of the VMA if tag storage couldn't be reserved. >>> >>> Only short term pins are allowed on MIGRATE_CMA pages, so I expect that the >>> pin will be released before the fault is replayed. Because of this, and >>> because it makes the code simpler, I chose not to migrate the page if tag >>> storage couldn't be reserved. >> >> There are still some cases that are theoretically problematic: vmsplice() >> can pin pages forever and doesn't use FOLL_LONGTERM yet. >> >> All these things also affect other users that rely on movability (e.g., CMA, >> memory hotunplug). > > I wasn't aware of that, thank you for the information. Then to ensure that the > process doesn't hang by replying the loop indefinitely, I'll migrate the page if > tag storage cannot be reserved. Looking over the code again, I think I can reuse > the same function that migrates tag storage pages out of the MTE VMA (added in > patch #21), so no major changes needed. It's going to be interesting if migrating that page fails because it is pinned :/ -- Cheers, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel