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Thu, 27 Nov 2025 13:52:52 -0800 (PST) MIME-Version: 1.0 References: <20251127011438.6918-1-21cnbao@gmail.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Fri, 28 Nov 2025 05:52:40 +0800 X-Gm-Features: AWmQ_blYpw-GPSWAvHSSwIXD1PKL1aIx4iCUo78DT2gXpdF1CZ018OhwLE5_XJY Message-ID: Subject: Re: [RFC PATCH 0/2] mm: continue using per-VMA lock when retrying page faults after I/O To: Matthew Wilcox Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-fsdevel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 874CB1C0007 X-Rspamd-Server: rspam02 X-Stat-Signature: 8wfzs4ktjteck5z3gjqooseayrwucqmt X-Rspam-User: X-HE-Tag: 1764280373-962048 X-HE-Meta: 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 xFY44uHJ YHzHBG01X47n3/HYDM7TtB5z8qW98UUC6/4Pa4PSNfBIE7Z0tQL8zSXW0Lb9RzT05VlMrIuS1yPTSbd76sbIIx81LXObq2F+2rqH+NLHzEyQprQyuMGx7oOP6JLNhgpVkKT/EMpxVnhuProVtk/7htYFzffUOoZKZB6zlq+8Re2Hkv4pc1e8s/tVmC9pWcSGSodoCwihCTpw16SaxomutDmuDFzZfWwUZ4bhCyZWrBklH+GWHvX4zcHWa9kHqDG7JIe8GXvSuHLpXsq1FyWmw5tzKCIY6pFs/XGDdYBNZMseEh3unemmP+qlI1Nb8BEq4KB20hYH3rf/gyGAJaP4G6XErEvVQHZ6lko9SuY9RSHLUc0rcGlmuM6ejuuyv2zSBfH8G3h1lztWF34f5uBeCMaL8aBQ94dTp50GHUB/8CFE2qPJvS/iFlpz7kg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 Fri, Nov 28, 2025 at 4:29=E2=80=AFAM Barry Song <21cnbao@gmail.com> wrot= e: > > On Fri, Nov 28, 2025 at 3:43=E2=80=AFAM Matthew Wilcox wrote: > > > > [dropping individuals, leaving only mailing lists. please don't send > > this kind of thing to so many people in future] Apologies, I missed this one. The output comes from ./scripts/get_maintainer.pl. If you think the group i= s too large, I guess we should at least include Suren, Lorenzo, David, and a few others in the discussion? [...] > > > > > This use case also manages to get utterly hung-up trying to do reclaim > > today with the mmap_lock held. SO it manifests somewhat similarly to > > your problem (everybody ends up blocked on mmap_lock) but it has a > > rather different root cause. If I understand the use case correctly, I believe retrying with the per-VMA lock would also be very helpful. Previously, we always retried using mmap_lock, which can be difficult to acquire under heavy contention, leadin= g to long latency while the pages might be reclaimed. With the per-VMA lock, = it is much easier to hold and proceed with the work. Thanks Barry