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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00709E7719A for ; Sat, 11 Jan 2025 20:31:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 815B06B0088; Sat, 11 Jan 2025 15:31:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7C8156B0089; Sat, 11 Jan 2025 15:31:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6B6A46B008C; Sat, 11 Jan 2025 15:31:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 534426B0088 for ; Sat, 11 Jan 2025 15:31:48 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 02FD281566 for ; Sat, 11 Jan 2025 20:31:47 +0000 (UTC) X-FDA: 82996317096.29.3F2B5BE Received: from mail-ed1-f42.google.com (mail-ed1-f42.google.com [209.85.208.42]) by imf07.hostedemail.com (Postfix) with ESMTP id 110D840005 for ; Sat, 11 Jan 2025 20:31:45 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=MuAfruHc; spf=pass (imf07.hostedemail.com: domain of mjguzik@gmail.com designates 209.85.208.42 as permitted sender) smtp.mailfrom=mjguzik@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1736627506; 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=MslvBwVp8G0PqfNk0PqWhn2Nba3mKE6gkZqPy7s3dYc=; b=EI24wFdNwN9fNdB7GMfn132vBI9p+9uViCHKfKGzudBzYr5g9y6Ux7+7CNdVgzNSTNuvfE WO8dZ7HohTE1wNbgqhYPuEQTlPBeFsGCzhEEPzW4jW3L4ZK4uc4YALN358vN1IAP7eNue4 YPlh10eAGadRBZNIac4gDCe5dUBR2pU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1736627506; a=rsa-sha256; cv=none; b=IXLv6Bl9aFg3UBMCdOK7Sw+31Rc1RHPcCduBdwr5/DSfk99Iurv+FJyfYUiKkxCFtoLs6+ QMAPR3/j+55Nm+Tbi/E6S5l9nUlepshBkv89jgXWhp6LM2rcbfc8gPcJKxvqFp0ZgzaoA3 G6ySMzt4P8SVdRSW6S3Y1Mr5fiUka2U= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20230601 header.b=MuAfruHc; spf=pass (imf07.hostedemail.com: domain of mjguzik@gmail.com designates 209.85.208.42 as permitted sender) smtp.mailfrom=mjguzik@gmail.com; dmarc=pass (policy=none) header.from=gmail.com Received: by mail-ed1-f42.google.com with SMTP id 4fb4d7f45d1cf-5d122cf8e52so5122076a12.1 for ; Sat, 11 Jan 2025 12:31:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1736627504; x=1737232304; darn=kvack.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=MslvBwVp8G0PqfNk0PqWhn2Nba3mKE6gkZqPy7s3dYc=; b=MuAfruHc/g9UeXA86Y6bLo5jEe8bJSGDKn7GeBYn2kSQget6H5xgiXxf94N96SkwRg fPi1BylDxzwoqEGL7ezZG9WxyDTtfO4qz86yXoVHizUW/J5fwg+u3SpLnRPShdBkrnB/ LZYa6vl2Ktz2yUSzcixyo03edDkb6qNhdqWYhZ2T0Jnl7hHQZBnpbxoacKaS2I3XPejX r9kW7FKF9/cxFTfxqZWBwDT4WyDy1AI1YnEUdm6nJYzyZZBXQ0lwdFxw4AyLfsdMluVb McLAC0bvsjPw8txWexPQ/PRaMQzCZfz/o+Hy+HYarMkisunwP9R8aC87DX837dcJ0HjF Lg4A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1736627504; x=1737232304; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MslvBwVp8G0PqfNk0PqWhn2Nba3mKE6gkZqPy7s3dYc=; b=n3k3AwGhYt3bhEqdbEiul57OR5qLX/0YgS1mxeTchldYv/cr3VKl606WjMLqLTekJS L4tO6BETQ6997nmSEJkwbyTeJ0js3GOv1G96eiG1Q9EQyDldo6g28C/mZlutVnDOc/Wc ro0FqgY59QkwPgCgTZsZFrHnImHUXsUmKOpV1WlruC+mKGHQtAJPAORyyvj5O1keX3e3 89uWeQSW1iTf4LU/D/CoJiPxmYnmq4+kYXjg4GQbQAYbUs1HduRLxqjfg8FsOYnF/Jpe 0f3LXHdyNeO0lZmC5BM91FWxrmmnYUoOBLeUX13PYD+5V5S8U9PCAZ26PGxyLAvTi/Oo c6pw== X-Forwarded-Encrypted: i=1; AJvYcCXaygR54VR4t3V+7GlJUTutbFh0ovdHBinfiuUZ55+fCPMDy9FHvb/h+39umQWh6MyJcL3t9ediag==@kvack.org X-Gm-Message-State: AOJu0Yw5YLOPOQVqIGfFFVmIMwIqlTQe+PovI+pZQ2wH7tWIQ/taGsbg MhnsA+ZjhlIO2b6MU5LqAUjYI3xPubNAMy/NZqbtNnrM3h2PaVn60L1DwuVQpzgHWkkB0cDPx/c hynTY4zypCrG/u7rvnZefCcAR3jU= X-Gm-Gg: ASbGncuWBulNRjID9SjJnPkNfL+PfgH0MtddeyDF+BOvjRhYReQ08DePjHgZ7X4oBui SzGo3oBzntLqh04wB7esTqjqDS7G+Q4TNuh3V X-Google-Smtp-Source: AGHT+IHuXJeqlgCckMeQ+w12Yjk3JH+vgnCauIut0U6G3C0fvr0fdunF+UtgkkpqvxSBAKKB5ehiw3elG85BZ+zKhiU= X-Received: by 2002:a05:6402:2790:b0:5d4:5e4:1555 with SMTP id 4fb4d7f45d1cf-5d972e148dbmr14181767a12.19.1736627504093; Sat, 11 Jan 2025 12:31:44 -0800 (PST) MIME-Version: 1.0 References: <20250111042604.3230628-1-surenb@google.com> <20250111042604.3230628-12-surenb@google.com> In-Reply-To: From: Mateusz Guzik Date: Sat, 11 Jan 2025 21:31:31 +0100 X-Gm-Features: AbW1kvZ_ZJ9-8LiNseFXH-qVMqlLy5y7326TflNCxRehrLh15qB8CHaQI67q6CU Message-ID: Subject: Re: [PATCH v9 11/17] mm: replace vm_lock and detached flag with a reference count To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, peterz@infradead.org, willy@infradead.org, liam.howlett@oracle.com, lorenzo.stoakes@oracle.com, david.laight.linux@gmail.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, lokeshgidra@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, klarasmodin@gmail.com, richard.weiyang@gmail.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 110D840005 X-Stat-Signature: p3ury1t59ezhbgwtwzmesysoyj5uzbb5 X-Rspam-User: X-HE-Tag: 1736627505-520440 X-HE-Meta: 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 AzEuIeCZ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000258, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Jan 11, 2025 at 9:14=E2=80=AFPM Suren Baghdasaryan wrote: > > On Sat, Jan 11, 2025 at 3:24=E2=80=AFAM Mateusz Guzik = wrote: > > The previous modification of this spot to raw_read_seqcount loses the > > acquire fence, making the above comment not line up with the code. > > Is it? From reading the seqcount code > (https://elixir.bootlin.com/linux/v6.13-rc3/source/include/linux/seqlock.= h#L211): > > raw_read_seqcount() > seqprop_sequence() > __seqprop(s, sequence) > __seqprop_sequence() > smp_load_acquire() > > smp_load_acquire() still provides the acquire fence. Am I missing somethi= ng? > That's fine indeed. In a different project there is an equivalent API which skips barriers, too quick glance suggested this is what's going on here. My bad, sorry for false alarm on this front. :) --=20 Mateusz Guzik