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[73.183.52.120]) by smtp.gmail.com with ESMTPSA id af79cd13be357-914f86ff80esm825920285a.13.2026.05.28.06.45.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 May 2026 06:45:39 -0700 (PDT) From: Brian Masney Date: Thu, 28 May 2026 09:45:10 -0400 Subject: [PATCH] docs: mm: clarify that user_reserve_kbytes has no effect when overcommit_memory is set to 0 or 1 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260528-mm-clarify-docs-v1-1-aa88e83b4bfd@redhat.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/x3MQQqAIBBA0avErBuogUy6SrQwHWsgKxSikO6et HyL/zMkjsIJhipD5EuSHHtBW1dgV7MvjOKKgRpSTUcaQ0C7mSj+QXfYhL0ys/aaNCkHpToje7n /4zi97wffbkU/YQAAAA== X-Change-ID: 20260528-mm-clarify-docs-76ab8f82826d To: Jonathan Corbet , Shuah Khan , Andrew Morton Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Matthew Storr , Brian Masney X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1365; i=bmasney@redhat.com; s=20250903; h=from:subject:message-id; bh=nhsyimBQ315HBr0MkYf5dXK4pQhhIUcYzbD+bgi/3No=; b=owGbwMvMwCW2/dJd9di6A+2Mp9WSGLIk3P7+dlx5slO2ew+X+KooNZ7Fgf4L31/bE8KWtin3l +qGqcv9O0pYGMS4GGTFFFmW5BoVRKSusr13R5MFZg4rE8gQBi5OAZjIgUqG/0nX9onfjnuV7KJz X/jm/tC+7DmPpetWv7kc3FNxJ/JUxmaG7+6f9O9VyuszvjTNrjvvOZunt0HjbFRHSvukvWKKdtW sAA== X-Developer-Key: i=bmasney@redhat.com; a=openpgp; fpr=A46D32705865AA3DDEDC2904B7D2DD275D7EC087 Looking at __vm_enough_memory() in mm/util.c, user_reserve_kbytes has no effect when overcommit_memory is set to 0 or 1. The documentation for overcommit_memory already references user_reserve_kbytes when the flag is set to 2. Let's go ahead and add a clarification to user_reserve_kbytes in vm.rst that it has no effect when overcommit_memory is set to 0 or 1. Signed-off-by: Brian Masney Acked-by: David Hildenbrand (Arm) --- Documentation/admin-guide/sysctl/vm.rst | 2 ++ 1 file changed, 2 insertions(+) diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-= guide/sysctl/vm.rst index 97e12359775c..b9b0c218bfb4 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -1034,6 +1034,8 @@ min(3% of current process size, user_reserve_kbytes) = of free memory. This is intended to prevent a user from starting a single memory hogging process, such that they cannot recover (kill the hog). =20 +This setting has no effect when overcommit_memory is set to 0 or 1. + user_reserve_kbytes defaults to min(3% of the current process size, 128MB). =20 If this is reduced to zero, then the user will be allowed to allocate --- base-commit: e7d700e14934e68f86338c5610cf2ae76798b663 change-id: 20260528-mm-clarify-docs-76ab8f82826d Best regards, --=20 Brian Masney