Re: [PATCH 7.2 v16 03/13] mm/khugepaged: rework max_ptes_* handling with helper functions

Usama Arif
2026-04-20T13:16:20Z

On Sun, 19 Apr 2026 12:57:40 -0600 Nico Pache <npache@redhat.com> wrote:

> The following cleanup reworks all the max_ptes_* handling into helper
> functions. This increases the code readability and will later be used to
> implement the mTHP handling of these variables.
>
> With these changes we abstract all the madvise_collapse() special casing
> (dont respect the sysctls) away from the functions that utilize them. And
> will later in this series to cleanly restrict mTHP collapses behaviors.
>
> Suggested-by: David Hildenbrand <david@kernel.org>
> Signed-off-by: Nico Pache <npache@redhat.com>
> ---
> mm/khugepaged.c | 114 +++++++++++++++++++++++++++++++++---------------
> 1 file changed, 78 insertions(+), 36 deletions(-)
>

The old code re-read khugepaged_max_ptes_* on every loop iteration; the new
code snapshots them once per scan call. If userspace writes the sysctl
mid-scan, old behavior reacted within the scan, new behavior uses the value
sampled at entry. This is completely ok IMO, but might be good to call out.

Also might be good to write no functional change intended apart from
above in the commit message?

Acked-by: Usama Arif <usama.arif@linux.dev>