From: Johannes Weiner <hannes@cmpxchg.org>
To: Nimrod Oren <noren@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Jonathan Corbet <corbet@lwn.net>,
Shuah Khan <skhan@linuxfoundation.org>,
Randy Dunlap <rdunlap@infradead.org>, Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Nico Pache <nico.pache@linux.dev>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Kiryl Shutsemau <kas@kernel.org>,
Brendan Jackman <brendan.jackman@linux.dev>,
David Laight <david.laight.linux@gmail.com>,
linux-mm@kvack.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: stop recalculating min_free_kbytes once set by userspace
Date: Wed, 14 Oct 2026 22:32:14 +0200 [thread overview]
Message-ID: <20261014203214.GF371161@cmpxchg.org> (raw)
In-Reply-To: <20261014140859.1006967-1-noren@nvidia.com>
On Wed, Oct 14, 2026 at 05:08:59PM +0300, Nimrod Oren wrote:
> min_free_kbytes is recalculated on memory hotplug and on THP sysfs
> writes. The new value comes from calculate_min_free_kbytes() or, while
> THP is enabled, from set_recommended_min_free_kbytes(). A value written
> to the vm.min_free_kbytes sysctl is replaced whenever the new value is
> higher, so a lower value does not stick. This matters most when THP is
> enabled on configurations with large pageblocks, where the new value
> can be excessive [1].
>
> Stop recalculating min_free_kbytes once a value has been written to the
> sysctl. Systems where the sysctl is never written keep the current
> behavior.
>
> Link: https://lore.kernel.org/r/20260716173504.760369-1-noren@nvidia.com/ [1]
> Suggested-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
> Link: https://lore.kernel.org/r/d202dcc3-d7d7-4e98-a9a5-3137cfbfd041@kernel.org/
> Signed-off-by: Nimrod Oren <noren@nvidia.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
next prev parent reply other threads:[~2026-10-14 20:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-14 14:08 [PATCH] mm: stop recalculating min_free_kbytes once set by userspace Nimrod Oren
2026-10-14 20:32 ` Johannes Weiner [this message]
2026-10-14 20:34 ` Zi Yan
2026-10-14 21:48 ` Andrew Morton
2026-10-15 7:10 ` Vlastimil Babka (SUSE)
2026-10-15 9:19 ` Lorenzo Stoakes (ARM)
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