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b=yyipCU4al7wZUCxLPJtBmtOl5273fibvVCgLfHNF7po9bNlRLGzN210UCpk8JwAsi doC9AmMcNB38C98pfORUq0o7zRTx6j3Dt14cazQjO+uIbCyhbpjfb5aJVWVrHAS8kP Cm+cpgWnTUI3Up4Tp9CQJNZTLyemXpfPW13JBFn0= Date: Mon, 5 Oct 2026 05:54:02 -0700 From: Andrew Morton To: Vernon Yang Cc: david@kernel.org, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, baoquan.he@linux.dev, hannes@cmpxchg.org, mhocko@kernel.org, ljs@kernel.org, roman.gushchin@linux.dev, dave@stgolabs.net, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vernon Yang , stable@vger.kernel.org Subject: Re: [PATCH] mm: vmscan: don't count per-node proactive reclaim as memory pressure Message-Id: <20261005055402.61065464d9c66f1540a08c94@linux-foundation.org> In-Reply-To: References: <20261005062236.564210-1-vernon2gm@gmail.com> <20261004233615.df26e580c1bc916c7f3a23b2@linux-foundation.org> 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-Stat-Signature: zucenot9ncj5ep153m1nkp8g836k97bw X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: A0EC31A000A X-HE-Tag: 1791204844-744674 X-HE-Meta: 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 wTvy1WL0 gEAGUt8Plz0lKITeCK5GmTIgT/epkJx6B7p6xV1QRYTpIH8kO+rGVMdJ6YyRmW5njq7d9BnKw30ydLROmyAlewB1cBxB7VImOfml0YFzp4BgiKc2IEWQ5ln4TbD2pSy09cswxigK4P73bC/vbhfS2nE03CSHTMvB5Bn9WwXWAsovZnjFxDd1wxNxiUCqU8a8Jsz4GLHPeJMPwt5dGs7g5/HNqEMjsf5ojAm6aS8jAERxAS/MBFajpyLdmlO17oavHjJaAgdmcq7RQOQxec/JsLE8g6A2BPav5vCdjXfpNb0Qv8mw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 5 Oct 2026 18:10:45 +0800 Vernon Yang wrote: > the phenomenon resembling > > > senpai will appear again. > > > > What is this? > > This is commit e22c6ed90aa9, which addresses a scenario mentioned in > memory limits of a cgroup, in detail as follows: > > Currently, this reclaim activity is accounted as memory pressure in the > cgroup that the writer(!) belongs to. This is unexpected. It > specifically causes problems for senpai > (https://github.com/facebookincubator/senpai), which is an agent that > routinely adjusts the memory limits and performs associated reclaim work > in tens or even hundreds of cgroups running on the host. The cgroup that > senpai is running in itself will report elevated levels of memory > pressure, even though it itself is under no memory shortage or any sort of > distress. ah, thanks. It's arguably appropriate that the procfs-writing process gets blamed for the I/O which it caused, but clearly that's the wrong place to account the memory pressure.