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Sat, 11 Jan 2025 12:58:22 -0800 (PST) MIME-Version: 1.0 References: <20250111042604.3230628-1-surenb@google.com> <20250111042604.3230628-12-surenb@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Sat, 11 Jan 2025 12:58:10 -0800 X-Gm-Features: AbW1kvaJ43SEywDn5XzSIyXFLgO9NV09UA7g7hE5IJyHZ53Gp9uaIDe6HvGxsK4 Message-ID: Subject: Re: [PATCH v9 11/17] mm: replace vm_lock and detached flag with a reference count To: Mateusz Guzik 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-Queue-Id: 5EEEB8000A X-Stat-Signature: 1e9yxdtpts47od8ssd1ku691gre813yk X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1736629103-193232 X-HE-Meta: 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 sTFQjrU/ TTyICsDhRZzuj/ivZV1j73hauxZtSefHqIuzO03QUJiEX+pyO5YYH4zhpbdjxBGixV0LiDszjcYxOYtD0c1d+N/NG8SK9RuoOJ7iPCx/6dZtGHdi/aL6juxR/sNuEdHJXtaN0xj/fI6/DLSXXGRaR1ZCPo/WgDVk9dOid6cX3g1dkFkrLh24YQEv75vlb8hLvUsZ+2j9Ghsb2u8OPO6DwIHffSlL6EpCHmRTL5jQ2FGPT0kzdyA3xiFV0HVdBuXAqeaxiYn0erv9yewCYTTzv/0XgiGFDlDja6w2HJPEXexZh+S+ttEyVOu9ecpG1o+avBfiiMeuplhsFMhOTUdtYTfYjriFYvv1PHDH0CZNycN/OfC6DvjK+Junf5Po2EzN2EirhMNDWKvDzMsaLokPYcHoGUEhrKCGeAvyu X-Bogosity: Ham, tests=bogofilter, spamicity=0.005920, 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 12:31=E2=80=AFPM Mateusz Guzik = wrote: > > 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/seqloc= k.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 somet= hing? > > > > 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. :) No worries. Better to double-check than to merge a bug. Thanks, Suren. > > -- > Mateusz Guzik