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 05F39547058 for ; Wed, 7 Oct 2026 00:49:00 +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=1791334141; cv=none; b=EzdBYU9E0b9XsTidrKq/BfhGRlWItipJgnebyX8Rg2hJ71+HyVhagZndpYxkbREJo4syEsw6IHB5+hDd3YLs5v9uJ5EYR9N/NYvndcaQLuT3jpjLAALlmGh5qmlqgt3BOeloiYoOak0qmvFeqWsJes806NecP623Swt7KfZyD4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791334141; c=relaxed/simple; bh=IX4XmnqKHawUHflhwPxz6ctwLhz72YqRjfFZbvJNloE=; h=Date:To:From:Subject:Message-Id; b=G7rel3QlZMqITJE/slVDf6ASpjNSKTfiMpNbsOvM+liAw3pI5/4Gd1UC91fm93Rrm91OZp7FvRnFyMLXMn6Jvjek3dhmX22vsOWUMT2UY1DSTltbBfKBcRBNAw3NseWXlabVYdvBJkpAcWL6Qb9sb4U/t2a0tDEapwwRMMpnqYA= 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=gl4zBlGd; 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="gl4zBlGd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF5961F0089C; Wed, 7 Oct 2026 00:48:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791334139; bh=BMqXHJu8zW9HT+9eJLghGCRPnUAYlq9+FYpOh2SwJ0s=; h=Date:To:From:Subject; b=gl4zBlGdFWGOto+I67iFxSMyl6Xj/+H3Rjxx4a23baDNH4yernaH5SwtXfdlpd8Tt Sm1cllz2g+V1Uh2fpbuUk9W2tAM4xPeJhP8m01KCQgV9TbpL/Ixmas8T3skdtLkCvM P8x7DVVUoV8kZtJYd6nJOUrMhHvhFuw6YsnpnBSc= Date: Tue, 06 Oct 2026 17:48:59 -0700 To: mm-commits@vger.kernel.org,tj@kernel.org,shakeel.butt@linux.dev,roman.gushchin@linux.dev,muchun.song@linux.dev,mkoutny@suse.com,mhocko@suse.com,hannes@cmpxchg.org,cuitao@kylinos.cn,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] docs-cgroup-document-empty-write-behavior-of-memory-limit-knobs.patch removed from -mm tree Message-Id: <20261007004859.CF5961F0089C@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: docs: cgroup: document empty-write behavior of memory limit knobs has been removed from the -mm tree. Its filename was docs-cgroup-document-empty-write-behavior-of-memory-limit-knobs.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Tao Cui Subject: docs: cgroup: document empty-write behavior of memory limit knobs Date: Wed, 26 Aug 2026 10:17:53 +0800 A maintenance script on a cluster wrote an unset variable into memory.max of a workload cgroup; the variable expanded to an empty string, the write succeeded, and the workload in the cgroup was OOM-killed. Nothing pointed back at the write, so it took quite some time to trace the OOM kills to that script. The memory controller documentation does not say what an empty write does; the cpuset controller documents its empty-value semantics. The actual behavior is that the empty string is accepted as 0. Reproduced on a k8s cluster (v1.29, cgroup v2, two-container pod, 384M limit): # LIMIT= # echo "$LIMIT" > $CG/memory.max # echo $? 0 m6demo 0/2 OOMKilled 0 Memory cgroup out of memory: Killed process 339529 (sleep) ... anon-rss:32kB State it where the interface files are introduced, alongside the existing notes on units and page rounding. Link: https://lore.kernel.org/all/aoVUlFdZYLFn_gvJ@tiehlicka/ Link: https://lore.kernel.org/20260826021753.197871-1-cui.tao@linux.dev Signed-off-by: Tao Cui Signed-off-by: Andrew Morton Acked-by: Michal Hocko Acked-by: Shakeel Butt Cc: Johannes Weiner Cc: Michal Koutný Cc: Muchun Song Cc: Roman Gushchin Cc: Tejun Heo --- Documentation/admin-guide/cgroup-v2.rst | 4 ++++ 1 file changed, 4 insertions(+) --- a/Documentation/admin-guide/cgroup-v2.rst~docs-cgroup-document-empty-write-behavior-of-memory-limit-knobs +++ a/Documentation/admin-guide/cgroup-v2.rst @@ -1321,6 +1321,10 @@ All memory amounts are in bytes. If a v PAGE_SIZE is written, the value may be rounded up to the closest PAGE_SIZE multiple when read back. +For the limit files described below, an empty or all-whitespace +write is accepted and sets the limit to 0. To disable a limit, +write "max"; to set it to zero explicitly, write "0". + memory.current A read-only single value file which exists on non-root cgroups. _ Patches currently in -mm which might be from cuitao@kylinos.cn are