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b=PVYDC95njTGNGSvrI17qkadoaNvtm+GWaVh4lh+NpLDGAcI1tgSaOKNYRFnGebqTY 4INwLt2VzXTqAyc75l8cZFUHvX5I0La/UG933dRQz/sa+D4hafDTB/rNL92bx3lAfl 2snx0KOs1WrQoTcBm5I7F3gCB4lC9IO+mcBVCdIg= Date: Fri, 18 Sep 2026 08:44:42 -0700 From: Andrew Morton To: Suren Baghdasaryan Cc: liam@infradead.org, ljs@kernel.org, vbabka@kernel.org, david@kernel.org, willy@infradead.org, jannh@google.com, paulmck@kernel.org, pfalcato@suse.de, xueyuan.chen21@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v5 0/7] read proc/pid/smaps_rollup under per-vma lock Message-Id: <20260918084442.c95296b529cd8bf003e38bd5@linux-foundation.org> In-Reply-To: <20260918153318.758387-1-surenb@google.com> References: <20260918153318.758387-1-surenb@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 873534000A X-Stat-Signature: 4ncnetwfrchn769taf8tazoj7xw6hes9 X-Rspam-User: X-HE-Tag: 1789746284-230408 X-HE-Meta: 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 0S0txq62 +CVKfPdE5L5zXPVcfKxv/1ChosyVKQ8IjyczQH7ZuPonStISj7QVCgrPF/fQlzUoFiQTCoGMxIpDTxtQFlx8RsW7INuwbO93DJ+11MVgLqJP+TMexQfxTEY5s2vjPwXjeAtGlIHcNUbFswzjfTGqSTaOOSJtAXFy6xwBLKAPzU6TIoRjXYd175kXE5THYFSPSr///iO+NY5xcjDmI2HGEDp1zdS+GgXkuzG9dv600AExqAgBcdBn8CeGPa7tJ2ZyjPyS4WbbU+CKKSUeRVE9wCqJQXG9yyOuZuwR8nDMjMvMMYaQAn6F0J/O1rTVAYOj/F4wlxVtWFby0WD35+UUcDAQmp3jfPN/QEu3GCD/A4/TphY1a0Z+qh3U1twJHiZ85NpT7WHMS84lmfamLtNjTZzLiPERk+SYcgXzSIo0J8DHbiCQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 18 Sep 2026 08:33:11 -0700 Suren Baghdasaryan wrote: > proc/pid/smaps_rollup can be read using the combination of RCU and > VMA read locks, similar to proc/pid/{maps|smaps|numa_maps}. RCU is > required to safely traverse the VMA tree and VMA lock stabilizes the > VMA being processed and the pagetable walk. > Note that we have to keep the logic to drop mmap_lock on contention > because even when using per-VMA locks we might have to fall back to > holding the mmap_lock. > > The first 5 patches are cleanups making later change simpler. The main > change is in patch 6. Patch 7 extends existing proc-maps-race tearing > test to verify smaps_rollup content. Thanks, I added this to mm.git's mm-new branch.