Re: [PATCH v5 05/14] mm: remove READ_ONLY_THP_FOR_FS Kconfig option

[Wei Yang]

On Wed, Apr 29, 2026 at 11:35:28AM -0400, Zi Yan wrote:
>After removing READ_ONLY_THP_FOR_FS check in file_thp_enabled(),
>khugepaged and MADV_COLLAPSE can run on FSes with PMD THP pagecache
>support even without READ_ONLY_THP_FOR_FS enabled. Remove the Kconfig first
>so that no one can use READ_ONLY_THP_FOR_FS as upcoming commits remove
>mapping->nr_thps, which its safe guard mechanism relies on.
>
>Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@xxxxxxxxxx>
>Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
>Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
>---
> mm/Kconfig | 11 -----------
> 1 file changed, 11 deletions(-)
>
>diff --git a/mm/Kconfig b/mm/Kconfig
>index e221fa1dc54d0..27dc5b0139ba6 100644
>--- a/mm/Kconfig
>+++ b/mm/Kconfig
>@@ -936,17 +936,6 @@ config THP_SWAP
> 
> 	  For selection by architectures with reasonable THP sizes.
> 
>-config READ_ONLY_THP_FOR_FS
>-	bool "Read-only THP for filesystems (EXPERIMENTAL)"
>-	depends on TRANSPARENT_HUGEPAGE
>-
>-	help
>-	  Allow khugepaged to put read-only file-backed pages in THP.
>-
>-	  This is marked experimental because it is a new feature. Write
>-	  support of file THPs will be developed in the next few release
>-	  cycles.
>-

Hi,

I see hugepage_enabled() in khugepaged.c still use READ_ONLY_THP_FOR_FS.

> config NO_PAGE_MAPCOUNT
> 	bool "No per-page mapcount (EXPERIMENTAL)"
> 	help
>-- 
>2.53.0
>

-- 
Wei Yang
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