From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 EF9252222A9; Mon, 5 Oct 2026 12:54:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791204845; cv=none; b=k+iidGdduWGzGQFya1Z92Nu2di2vav++9wbOL3mz5GkG04vTNQSLSbyxxFjv+/TJqbqNzTOmMExLhSHPFEr8SyW5RR/ISEdanYh34Ei9qWfhcGNkcU/DeSzvk83vsG58NkX9DQF7J7fnWPVqzk8+l1Rg1XG80vbMEbUmuqyUmdA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791204845; c=relaxed/simple; bh=QHXMqfCvgS8poFHJ2hnBrzonA+Ie7PSmWuuk17LQehw=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=P3ItEL01FwadooouM4nGAaOvVOd+CM3wJ+TwWL79TAZiyNq0yDJQzK3Bna/dw6GOOGIFSTeb78s3bVtYe+F03REck/eLeBMZHxbWTO/ba6gxveL6+DBycvFsDAJuoGuD9fXgNkkTaNff04T5IHsb77huJFccLjbC/H/N8na1jmg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=yyipCU4a; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="yyipCU4a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A667A1F000FF; Mon, 5 Oct 2026 12:54:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791204843; bh=L0WZ+X3bCrlqT3aScryv2WGhSJF2SKbCE0Wf2Qf1Okk=; h=Date:From:To:Cc:Subject:In-Reply-To:References; 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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.