Re: [PATCH -next] mm: don't try THP align for FS without get_unmapped_area

[Vlastimil Babka <vbabka@suse.cz>]

On 12/6/24 08:03, Kefeng Wang wrote:
> Commit ed48e87c7df3 ("thp: add thp_get_unmapped_area_vmflags()")
> changes thp_get_unmapped_area() to thp_get_unmapped_area_vmflags()
> in __get_unmapped_area(), which won't setup get_area for anonymous
> mappings, but it leads to always try THP align when file ops without
> '.get_unmapped_area' callback too as the get_area is NULL.
> 
> Since commit efa7df3e3bb5 ("mm: align larger anonymous mappings on
> THP boundaries") only want to enable THP align for anonymous, adding
> !file check to fix it.
> 
> Fixes: ed48e87c7df3 ("thp: add thp_get_unmapped_area_vmflags()")
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Yeah, well spotted.
Cc stable as we did for the others?

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/mmap.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 1c6bdffa13dd..b373486bd1c6 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -782,7 +782,7 @@ __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
>  
>  	if (get_area) {
>  		addr = get_area(file, addr, len, pgoff, flags);
> -	} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)
> +	} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && !file
>  		   && !addr /* no hint */
>  		   && IS_ALIGNED(len, PMD_SIZE)) {
>  		/* Ensures that larger anonymous mappings are THP aligned. */