From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 89BF4515897; Tue, 13 Oct 2026 15:09:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791904152; cv=none; b=XppUBD+cxkOGVotonBg3E04SIF9Khzs9lusYtv/yWIL2Ry1VJeMYyt2v220XgWAh1oWVxFzNXzvYYVe7cuc5dAkN1NopMXvIV4/YpuVTdcb0IBGzUUoWBMzrmtpbBlN2Esoy2gGt0XZQDBV6ygtt3fAwCQIN9WdWK+iow4FGdsM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791904152; c=relaxed/simple; bh=9blUwT6e0Ts6h04B3FpvA5wBGV5BTm958rVQ0HCmK9U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mV2CO/kavvkwo9xFZicj363g9TjINH2PCIFe3ZP57w1HJLIJjZiGeaSvRCz9F2dEMXooDgtgcIpcIXS5I931lm6a0TGVA/mWjYlLK/0GnGo3adiPK0J2yD/xVQWMog+JP6WShKYy3MOjSnPVwn50z9MlboS5HhrfUO5edrN136U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EmfZ3myr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EmfZ3myr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3097F1F0089D; Tue, 13 Oct 2026 15:09:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791904151; bh=orXAxipawcAD57KCvhEp9yEc9EqWE9+dKa+U7k41Y50=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=EmfZ3myrFSViuO5vxZpOvDHMlTSxQl6dXxBk9ppNQGjyEaYzJGw7v+RlLZUJt1TQx 48CJhDl52oyae7mYildPISLB2ujwobN08IuONu+Lpa5TfV7/U6VFjMY0Qwe0uCP4sn M15UnhN2hT/TVmDM4oehdRWnqden70b1/6XToUvjHTYLlRMXh5sfgOkj7f/FK8RWcf J6C55KmIC8qMNPDkUN/76WTLXmbWhOuBgdk3H7P5EOxv8dB3Tgogch9bRYb0svhLBq UZ45UVBXLxZXv8UbHVgSRnrYsaO2PxRdS/z2EQyCL1zVT4RDhoMkkYkEw1/ulzXc4i /dd5QHn0Vl64w== Message-ID: Date: Tue, 13 Oct 2026 17:09:05 +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] fs/proc/task_mmu: fix lost maps entries above 2^63 To: Stian Halseth , Andrew Morton Cc: Suren Baghdasaryan , "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: <20261013150712.1827315-1-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: <20261013150712.1827315-1-stian@itx.no> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/13/26 17:07, 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. > > Skip the rewind only for 0 and the two sentinels instead, with an > addr_is_sentinel() helper. > > 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: > v2: addr_is_sentinel() covering both sentinels, as the comment says > (David Hildenbrand). No functional change: m_start() returns early on > SENTINEL_VMA_END. Re-tested on the T4 (7.2.10): maps and smaps read at > 128 sizes, 200 and 1000 mappings, no lost lines. > v1: https://lore.kernel.org/all/20261011162019.922436-1-stian@itx.no/ > > 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 | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 5c54aebe21182..9fd6a360919b9 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -32,6 +32,11 @@ > #define SENTINEL_VMA_END -1 > #define SENTINEL_VMA_GATE -2 > > +static inline bool addr_is_sentinel(loff_t addr) Nit: no need for the "inline". The compiler is smart enough :) Acked-by: David Hildenbrand (Arm) -- Cheers, David