From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 928D0155322; Wed, 6 Aug 2025 16:35:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754498137; cv=none; b=ot1BxoTk/23d+NzGWuND6/uzxTArJlV1yM/qW1kjb8ChV5S0y9AUASkxERdRzAZrUTP/+TP2UwR7S4Tmf5E7MBAYUHlKGIOasHoSOFSMr/2/iWUHR8TTABtRqlNeN43EYvSgY6KJfD1Wq4GlnEUs+6JVw0jFZTMs373XZtYv/a8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754498137; c=relaxed/simple; bh=xGGpA95XAeb0WwdxHKDD91ns9hkx0Ye7AgEA8IpfDQM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=N4f+GRG7ScW3KLI1tpqD3gNmt3ramcVg47DPOyBUbjoOhZziP3JusvwTKzfUybsfWdIMuu77x0g4hQqI7T0vJKSYlS/TZr50gRbUQe9r7bF//z+WGtHvB3oHXRPekcKec+L+wKCGaS6cgCpGGP/wT4eMpHjpukkx9rGuJAwBmjo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=d/y054IB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="d/y054IB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA4AFC4CEE7; Wed, 6 Aug 2025 16:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754498135; bh=xGGpA95XAeb0WwdxHKDD91ns9hkx0Ye7AgEA8IpfDQM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d/y054IB3WTivroNoV2FuA+UveCHLltCgYNZqm23SCuo2K9wGbGR2ca6JyInOgSVe LYLjRM5pnbKC0QeVcHViZHHqT64AmrA7+rN4vgnhFxrEqyFoh23I1CaVCHNR80/chv +DuIUQynVIwoERpz8iCWEZg9uf1Nzr1Y2HH1TTNynQwuiRE2+hMbXXLE/j98m3NiCq INKjI9cpu4MAYIcc0N2+F4aHVyHz4y4h7OQdop9sNR0xVL7gnaINkSav9ExiAYebtU eivKoe6UotebTQfZDgo8QyQIrou2wX9HPTkpDlfL71wIAEzMUlsuOnJ0fwyvZXDGOq +rTtZl13re3PA== From: SeongJae Park To: Suren Baghdasaryan Cc: SeongJae Park , akpm@linux-foundation.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, david@redhat.com, vbabka@suse.cz, peterx@redhat.com, jannh@google.com, hannes@cmpxchg.org, mhocko@kernel.org, paulmck@kernel.org, shuah@kernel.org, adobriyan@gmail.com, brauner@kernel.org, josef@toxicpanda.com, yebin10@huawei.com, linux@weissschuh.net, willy@infradead.org, osalvador@suse.de, andrii@kernel.org, ryan.roberts@arm.com, christophe.leroy@csgroup.eu, tjmercier@google.com, kaleshsingh@google.com, aha310510@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v3 3/3] fs/proc/task_mmu: execute PROCMAP_QUERY ioctl under per-vma locks Date: Wed, 6 Aug 2025 09:35:32 -0700 Message-Id: <20250806163532.82466-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250806155905.824388-4-surenb@google.com> References: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Wed, 6 Aug 2025 08:59:04 -0700 Suren Baghdasaryan wrote: > Utilize per-vma locks to stabilize vma after lookup without taking > mmap_lock during PROCMAP_QUERY ioctl execution. If vma lock is > contended, we fall back to mmap_lock but take it only momentarily > to lock the vma and release the mmap_lock. In a very unlikely case > of vm_refcnt overflow, this fall back path will fail and ioctl is > done under mmap_lock protection. > > This change is designed to reduce mmap_lock contention and prevent > PROCMAP_QUERY ioctl calls from blocking address space updates. > > Signed-off-by: Suren Baghdasaryan Acked-by: SeongJae Park Thanks, SJ [...]