* Re: [PATCH] mm/khugepaged: use page_cache_sync_ra() directly
2026-07-16 8:32 [PATCH] mm/khugepaged: use page_cache_sync_ra() directly Aditya Prakash Srivastava
@ 2026-07-16 9:02 ` Dev Jain
2026-07-16 9:08 ` David Hildenbrand (Arm)
2026-07-16 9:11 ` Lorenzo Stoakes (ARM)
2 siblings, 0 replies; 5+ messages in thread
From: Dev Jain @ 2026-07-16 9:02 UTC (permalink / raw)
To: Aditya Prakash Srivastava, Andrew Morton, David Hildenbrand,
Lorenzo Stoakes
Cc: Zi Yan, Baolin Wang, Liam R . Howlett, Nico Pache, Ryan Roberts,
Barry Song, Lance Yang, linux-mm, linux-kernel
On 16/07/26 2:02 pm, Aditya Prakash Srivastava wrote:
> The static inline page_cache_sync_readahead() wrapper in pagemap.h
> is legacy and only wraps page_cache_sync_ra() after initializing
How exactly is this a legacy interface?
> a local readahead_control structure using DEFINE_READAHEAD.
>
> Modernize the khugepaged readahead call by using page_cache_sync_ra()
> directly. This avoids the legacy wrapper and aligns the khugepaged
> readahead implementation with other subsystems in the kernel.
I can see multiple callers of page_cache_sync_readahead.
>
> No functional change is introduced, as the logic and behavior
> remain identical.
>
> Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>
> ---
> mm/khugepaged.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 617bca76db49..2682b39401b2 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2331,10 +2331,10 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
> }
> } else { /* !is_shmem */
> if (!folio || xa_is_value(folio)) {
> + DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, index);
> +
> xas_unlock_irq(&xas);
> - page_cache_sync_readahead(mapping, &file->f_ra,
> - file, index,
> - end - index);
> + page_cache_sync_ra(&ractl, end - index);
> /* drain lru cache to help folio_isolate_lru() */
> lru_add_drain();
> folio = filemap_lock_folio(mapping, index);
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/khugepaged: use page_cache_sync_ra() directly
2026-07-16 8:32 [PATCH] mm/khugepaged: use page_cache_sync_ra() directly Aditya Prakash Srivastava
2026-07-16 9:02 ` Dev Jain
@ 2026-07-16 9:08 ` David Hildenbrand (Arm)
2026-07-16 9:11 ` Lorenzo Stoakes (ARM)
2 siblings, 0 replies; 5+ messages in thread
From: David Hildenbrand (Arm) @ 2026-07-16 9:08 UTC (permalink / raw)
To: Aditya Prakash Srivastava, Andrew Morton, Lorenzo Stoakes
Cc: Zi Yan, Baolin Wang, Liam R . Howlett, Nico Pache, Ryan Roberts,
Dev Jain, Barry Song, Lance Yang, linux-mm, linux-kernel
On 7/16/26 10:32, Aditya Prakash Srivastava wrote:
> The static inline page_cache_sync_readahead() wrapper in pagemap.h
> is legacy and only wraps page_cache_sync_ra() after initializing
> a local readahead_control structure using DEFINE_READAHEAD.
>
> Modernize the khugepaged readahead call by using page_cache_sync_ra()
> directly. This avoids the legacy wrapper and aligns the khugepaged
> readahead implementation with other subsystems in the kernel.
>
> No functional change is introduced, as the logic and behavior
> remain identical.
>
> Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>
> ---
> mm/khugepaged.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 617bca76db49..2682b39401b2 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2331,10 +2331,10 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
> }
> } else { /* !is_shmem */
> if (!folio || xa_is_value(folio)) {
> + DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, index);
> +
> xas_unlock_irq(&xas);
> - page_cache_sync_readahead(mapping, &file->f_ra,
> - file, index,
> - end - index);
> + page_cache_sync_ra(&ractl, end - index);
The page_cache_sync_readahead() call nicely wraps these two things.
You are essentially duplicating code, no?
So I also miss the point.
--
Cheers,
David
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/khugepaged: use page_cache_sync_ra() directly
2026-07-16 8:32 [PATCH] mm/khugepaged: use page_cache_sync_ra() directly Aditya Prakash Srivastava
2026-07-16 9:02 ` Dev Jain
2026-07-16 9:08 ` David Hildenbrand (Arm)
@ 2026-07-16 9:11 ` Lorenzo Stoakes (ARM)
2026-07-16 9:16 ` Aditya Prakash Srivastava
2 siblings, 1 reply; 5+ messages in thread
From: Lorenzo Stoakes (ARM) @ 2026-07-16 9:11 UTC (permalink / raw)
To: Aditya Prakash Srivastava
Cc: Andrew Morton, David Hildenbrand, Zi Yan, Baolin Wang,
Liam R . Howlett, Nico Pache, Ryan Roberts, Dev Jain, Barry Song,
Lance Yang, linux-mm, linux-kernel
On Thu, Jul 16, 2026 at 08:32:11AM +0000, Aditya Prakash Srivastava wrote:
> The static inline page_cache_sync_readahead() wrapper in pagemap.h
> is legacy and only wraps page_cache_sync_ra() after initializing
> a local readahead_control structure using DEFINE_READAHEAD.
As Dev notes there's nothing legacy about it, it's used in multiple places.
>
> Modernize the khugepaged readahead call by using page_cache_sync_ra()
> directly. This avoids the legacy wrapper and aligns the khugepaged
> readahead implementation with other subsystems in the kernel.
Nope, it's replacing a helper function that wraps something with open coding it
instead for no good reason.
>
> No functional change is introduced, as the logic and behavior
> remain identical.
>
> Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>
Sorry this patch is replacing a wrapper with open code for not really much
benefit.
> ---
> mm/khugepaged.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 617bca76db49..2682b39401b2 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2331,10 +2331,10 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
> }
> } else { /* !is_shmem */
> if (!folio || xa_is_value(folio)) {
> + DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, index);
> +
> xas_unlock_irq(&xas);
> - page_cache_sync_readahead(mapping, &file->f_ra,
> - file, index,
> - end - index);
> + page_cache_sync_ra(&ractl, end - index);
> /* drain lru cache to help folio_isolate_lru() */
> lru_add_drain();
> folio = filemap_lock_folio(mapping, index);
> --
> 2.47.3
>
Cheers, Lorenzo
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] mm/khugepaged: use page_cache_sync_ra() directly
2026-07-16 9:11 ` Lorenzo Stoakes (ARM)
@ 2026-07-16 9:16 ` Aditya Prakash Srivastava
0 siblings, 0 replies; 5+ messages in thread
From: Aditya Prakash Srivastava @ 2026-07-16 9:16 UTC (permalink / raw)
To: Lorenzo Stoakes (ARM)
Cc: Andrew Morton, David Hildenbrand, Zi Yan, Baolin Wang,
Liam R . Howlett, Nico Pache, Ryan Roberts, Dev Jain, Barry Song,
Lance Yang, linux-mm, linux-kernel
Thanks for the feedback. I agree that replacing the helper with
its open-coded implementation at a single call site doesn't
provide a meaningful improvement. I'll drop this patch.
Thanks,
Aditya
On Thu, Jul 16, 2026 at 2:41 PM Lorenzo Stoakes (ARM) <ljs@kernel.org> wrote:
>
> On Thu, Jul 16, 2026 at 08:32:11AM +0000, Aditya Prakash Srivastava wrote:
> > The static inline page_cache_sync_readahead() wrapper in pagemap.h
> > is legacy and only wraps page_cache_sync_ra() after initializing
> > a local readahead_control structure using DEFINE_READAHEAD.
>
> As Dev notes there's nothing legacy about it, it's used in multiple places.
>
> >
> > Modernize the khugepaged readahead call by using page_cache_sync_ra()
> > directly. This avoids the legacy wrapper and aligns the khugepaged
> > readahead implementation with other subsystems in the kernel.
>
> Nope, it's replacing a helper function that wraps something with open coding it
> instead for no good reason.
>
> >
> > No functional change is introduced, as the logic and behavior
> > remain identical.
> >
> > Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>
>
> Sorry this patch is replacing a wrapper with open code for not really much
> benefit.
>
> > ---
> > mm/khugepaged.c | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> > index 617bca76db49..2682b39401b2 100644
> > --- a/mm/khugepaged.c
> > +++ b/mm/khugepaged.c
> > @@ -2331,10 +2331,10 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
> > }
> > } else { /* !is_shmem */
> > if (!folio || xa_is_value(folio)) {
> > + DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, index);
> > +
> > xas_unlock_irq(&xas);
> > - page_cache_sync_readahead(mapping, &file->f_ra,
> > - file, index,
> > - end - index);
> > + page_cache_sync_ra(&ractl, end - index);
> > /* drain lru cache to help folio_isolate_lru() */
> > lru_add_drain();
> > folio = filemap_lock_folio(mapping, index);
> > --
> > 2.47.3
> >
>
> Cheers, Lorenzo
^ permalink raw reply [flat|nested] 5+ messages in thread