Re: [PATCH] bcachefs: fix alignment of VMA for memory mapped files on THP
From: Kent Overstreet
Date: Thu Jun 20 2024 - 08:51:47 EST
On Thu, Jun 20, 2024 at 09:22:42AM +0800, Youling Tang wrote:
> From: Youling Tang <tangyouling@xxxxxxxxxx>
>
> With CONFIG_READ_ONLY_THP_FOR_FS, the Linux kernel supports using THPs
> for read-only mmapped files, such as shared libraries. However, the
> kernel makes no attempt to actually align those mappings on 2MB
> boundaries, which makes it impossible to use those THPs most of the
> time. This issue applies to general file mapping THP as well as
> existing setups using CONFIG_READ_ONLY_THP_FOR_FS. This is easily
> fixed by using thp_get_unmapped_area for the unmapped_area function
> in bcachefs, which is what ext2, ext4, fuse, xfs and btrfs all use.
>
> Similar to commit b0c582233a85 ("btrfs: fix alignment of VMA for
> memory mapped files on THP").
>
> Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxx>
Thanks - applied