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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8F8B6CC6B0E for ; Tue, 13 Oct 2026 14:40:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 773916B0092; Tue, 13 Oct 2026 10:40:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 723AA6B0096; Tue, 13 Oct 2026 10:40:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5EB6A6B0098; Tue, 13 Oct 2026 10:40:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 2FDFE6B0092 for ; Tue, 13 Oct 2026 10:40:54 -0400 (EDT) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay05.hostedemail.com (Postfix) with ESMTP id AD8D840D39 for ; Tue, 13 Oct 2026 14:40:53 +0000 (UTC) X-FDA: 85317864786.28.F588F5E Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf18.hostedemail.com (Postfix) with ESMTP id D14401C0005 for ; Tue, 13 Oct 2026 14:40:51 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=E3dxMwqL; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1791902451; h=from:from:sender: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:dkim-signature; bh=JMF/X4p2JMQOAWL5F8hcgnR0xRgqfvQmfw3SYOWs+Bc=; b=eIw0lxL8vL0vaiZsJUDb4/2wzy8P0YwWH9mWX5pEyWgwc1H/ShZe4FJ9IAPY95VM/V+CIt 6TYAMrbeF2lHMC2NFiga4DNskrUAKLR4zuiX7PqkNnZGOWLgHFVER/CxE2uRHsypTcJC56 198SY5kd6C2x9inMpH64Ls5wAHMgX5M= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=E3dxMwqL; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1791902452; b=7mmKFsI7qbUnxLtA6zSw9dpoRfgdodbAJSnQknTjIUISKLjDh0kxtStwHP1CFL9hLLMCIk HG8DxNu2HrZI9Gj+QtRlBnFDuX1ye+0+0zSZURwMsU9J1jsUjThkJ7Q7RcyChTGvYoUBxY KfzdNUITMEMGQY4MrbwneJcdnu70xQs= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 75EF860A5F; Tue, 13 Oct 2026 14:40:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2FB81F000FF; Tue, 13 Oct 2026 14:40:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791902450; bh=JMF/X4p2JMQOAWL5F8hcgnR0xRgqfvQmfw3SYOWs+Bc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=E3dxMwqLMttYe0HqZS0dZWPQZ5GG3zyuI0bjf3NPCgljWbcwXvEdkz5wNfUKIR9uO zrID0Xq18gpwNsFxSeaTpXMu8IwYvTbAvA58g/QChfUKY8hGkNGiN4cQV5qWD6opX+ czt4bQbb2TFIbQ+a7fGK/AISz3uh4NW3NwTCV79PSHfDdS+t6BHS/IGf34Y/d5KAns M3gTuKmkeJop2tA3nk1lKWpdnTe5rxUBYy9KSRVGqkiyJWnz1hBMENfuevLW/x8W+N dnMl3rvQi04aFvYZ475GaDry7zGNs8sGWJ6xqhJ3Olx/m16Qsr2Sf2cBNTLEwlys6f Ia9OFnVh7q93g== Message-ID: Date: Tue, 13 Oct 2026 16:40:43 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fs/proc/task_mmu: fix lost maps entries above 2^63 To: Stian Halseth , Andrew Morton , Suren Baghdasaryan Cc: "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pedro Falcato , Andreas Larsson , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261011162019.922436-1-stian@itx.no> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+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: <20261011162019.922436-1-stian@itx.no> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D14401C0005 X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: i77b3pp7u1wo6euijcqjsbcpi44kyfx3 X-HE-Tag: 1791902451-332230 X-HE-Meta: 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 vZO26fxG jg7jCk37zLRb2D9BYTOd5gfFZMhvJy6TMfmmzy6ekCKMaRoFfOF1ZSckD440t0CBTOCXSL0bLx9Fa/wep2s3Mw2Y7I65M7MLWjl7PVHhCvGLF824Ld+06JhB89y0YOrE/yDpF2WLVTBX8zPK15YGLWdKZvdZEwN3GD+47CmDUVXlnFG2EA3NCxLX0y1txq7eEFLBTgiKlwr44U8WqAMBE/PHLI+giTQNPY/o6APsaReqlTMwj5V33u2QCwKPswEMkPxG82jntB8EwaKRkFaW6aL0mkn6aWV3eWOEEJOETxMPE6n7rcokueB4dUcaAtqDQLXfEnyrGe2GYJUpM77CsOMeqDH38U5g/SxPdw7053ZxW5bzHxQyQa+ejUqQ/fWXiLKOo Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/11/26 18:20, Stian Halseth wrote: > When a read of /proc/pid/{maps,smaps,numa_maps} resumes, m_start() > rewinds *ppos to priv->last_pos so that the vma which did not fit into > the previous buffer is shown again. It only does so for last_addr > 0, > meaning to exclude the start of the file and SENTINEL_VMA_GATE, but > last_addr is a signed loff_t holding a vm_end. sparc64 maps shared > libraries, anonymous memory and the stack above 0x8000000000000000, so > the rewind does not happen there and one entry is lost at every read() > boundary. > > Reading the maps file of a process with read sizes from 64 to 8192 > bytes in steps of 64 loses lines at 126 of the 128 sizes, smaps at 123 > and numa_maps at 97, and the proc-maps-race selftest fails 4 of its 6 > tests. Python's sys.remote_exec() reads maps with fgets() and fails > intermittently when it misses the libpython data mapping. > > Test for the two values that are not a vma end instead. > > Fixes: 5631da56c9a87 ("fs/proc/task_mmu: read proc/pid/maps under per-vma lock") > Closes: https://github.com/sparclinux/issues/issues/111 > Cc: stable@vger.kernel.org > Signed-off-by: Stian Halseth > --- > > Notes: > Tested on a SPARC T7-1 (sun4v, 7.3-rc5), a T4-1 (7.2.9) and a Sun Fire > V240 (sun4u, 7.3-rc5): no lost lines at any read size afterwards, and > Python's sys.remote_exec() test passes 20/20. On an amd64 KVM guest maps, > smaps, numa_maps and the proc selftests are unchanged. > > fs/proc/task_mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 5c54aebe21182..cdce513edcb1d 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -339,7 +339,7 @@ static void *m_start(struct seq_file *m, loff_t *ppos) > * Reset current position if last_addr was set before > * and it's not a sentinel. > */ > - if (last_addr > 0) > + if (last_addr && last_addr != SENTINEL_VMA_GATE) > *ppos = last_addr = priv->last_pos; > vma_iter_init(&priv->iter, mm, (unsigned long)last_addr); > hold_task_mempolicy(priv); I hope Suren can review as well. Would it be cleaner to reject any special values, that is, SENTINEL_VMA_END and SENTINEL_VMA_GATE? That would match the comment and the previous code idea: exclude only 0 and sentinels. Could consider a simple addr_is_sentinel() helper. -- Cheers, David