[PATCH] mm: remove unused alloc_pages_bulk_list()

[PATCH] mm: remove unused alloc_pages_bulk_list()

[Lorenzo Stoakes]

This function is not referenced anywhere else in the kernel, remove it.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
---
 include/linux/gfp.h | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 65a78773dcca..67c5164f4758 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -188,13 +188,6 @@ unsigned long alloc_pages_bulk_array_mempolicy(gfp_t gfp,
 				unsigned long nr_pages,
 				struct page **page_array);
 
-/* Bulk allocate order-0 pages */
-static inline unsigned long
-alloc_pages_bulk_list(gfp_t gfp, unsigned long nr_pages, struct list_head *list)
-{
-	return __alloc_pages_bulk(gfp, numa_mem_id(), NULL, nr_pages, list, NULL);
-}
-
 static inline unsigned long
 alloc_pages_bulk_array(gfp_t gfp, unsigned long nr_pages, struct page **page_array)
 {
-- 
2.38.1

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Matthew Wilcox]

On Sat, Dec 17, 2022 at 12:15:54AM +0000, Lorenzo Stoakes wrote:
> This function is not referenced anywhere else in the kernel, remove it.

I think we're waiting to see if any users show up.  It's only been 18
months or so, so perhaps wait a little longer?

Also, if we do get rid of this, then __alloc_pages_bulk() can lose
the "list" argument.

> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
> ---
>  include/linux/gfp.h | 7 -------
>  1 file changed, 7 deletions(-)
> 
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 65a78773dcca..67c5164f4758 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -188,13 +188,6 @@ unsigned long alloc_pages_bulk_array_mempolicy(gfp_t gfp,
>  				unsigned long nr_pages,
>  				struct page **page_array);
>  
> -/* Bulk allocate order-0 pages */
> -static inline unsigned long
> -alloc_pages_bulk_list(gfp_t gfp, unsigned long nr_pages, struct list_head *list)
> -{
> -	return __alloc_pages_bulk(gfp, numa_mem_id(), NULL, nr_pages, list, NULL);
> -}
> -
>  static inline unsigned long
>  alloc_pages_bulk_array(gfp_t gfp, unsigned long nr_pages, struct page **page_array)
>  {
> -- 
> 2.38.1
> 

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Lorenzo Stoakes]

+ Mel

On Sat, Dec 17, 2022 at 04:56:03AM +0000, Matthew Wilcox wrote:
> I think we're waiting to see if any users show up.  It's only been 18
> months or so, so perhaps wait a little longer?

Apologies, I should have researched the background of this further. I see it was
added speculatively in 0f87d9d30f.

> Also, if we do get rid of this, then __alloc_pages_bulk() can lose
> the "list" argument.

Ack. Will do a v2 if Mel feels it's appropriate to remove at this stage,
otherwise we can drop the idea and wait for users to emerge.

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Mel Gorman]

On Sat, Dec 17, 2022 at 08:34:58AM +0000, Lorenzo Stoakes wrote:
> + Mel
> 
> On Sat, Dec 17, 2022 at 04:56:03AM +0000, Matthew Wilcox wrote:
> > I think we're waiting to see if any users show up.  It's only been 18
> > months or so, so perhaps wait a little longer?
> 
> Apologies, I should have researched the background of this further. I see it was
> added speculatively in 0f87d9d30f.
> 
> > Also, if we do get rid of this, then __alloc_pages_bulk() can lose
> > the "list" argument.
> 
> Ack. Will do a v2 if Mel feels it's appropriate to remove at this stage,
> otherwise we can drop the idea and wait for users to emerge.

I reckon we should give it another few months until May. There has been
one user recently that tried to use list but it turned out arrays were
more appropriate.

-- 
Mel Gorman
SUSE Labs

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Yang Shi]

On Mon, Dec 19, 2022 at 2:07 AM Mel Gorman <mgorman@techsingularity.net> wrote:
>
> On Sat, Dec 17, 2022 at 08:34:58AM +0000, Lorenzo Stoakes wrote:
> > + Mel
> >
> > On Sat, Dec 17, 2022 at 04:56:03AM +0000, Matthew Wilcox wrote:
> > > I think we're waiting to see if any users show up.  It's only been 18
> > > months or so, so perhaps wait a little longer?
> >
> > Apologies, I should have researched the background of this further. I see it was
> > added speculatively in 0f87d9d30f.
> >
> > > Also, if we do get rid of this, then __alloc_pages_bulk() can lose
> > > the "list" argument.
> >
> > Ack. Will do a v2 if Mel feels it's appropriate to remove at this stage,
> > otherwise we can drop the idea and wait for users to emerge.
>
> I reckon we should give it another few months until May. There has been
> one user recently that tried to use list but it turned out arrays were
> more appropriate.

Another recent try was the patches for dm-crypt. However Mel suggested
adding a callback interface instead of using list since list is not
necessary for that usecase. Or are we talking about the same one?

I didn't get time to implement Mel's suggestion yet due to my
employment change. Hopefully I can find some time after the new year.

>
> --
> Mel Gorman
> SUSE Labs
>

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Mel Gorman]

On Tue, Dec 20, 2022 at 09:56:19AM -0800, Yang Shi wrote:
> On Mon, Dec 19, 2022 at 2:07 AM Mel Gorman <mgorman@techsingularity.net> wrote:
> >
> > On Sat, Dec 17, 2022 at 08:34:58AM +0000, Lorenzo Stoakes wrote:
> > > + Mel
> > >
> > > On Sat, Dec 17, 2022 at 04:56:03AM +0000, Matthew Wilcox wrote:
> > > > I think we're waiting to see if any users show up.  It's only been 18
> > > > months or so, so perhaps wait a little longer?
> > >
> > > Apologies, I should have researched the background of this further. I see it was
> > > added speculatively in 0f87d9d30f.
> > >
> > > > Also, if we do get rid of this, then __alloc_pages_bulk() can lose
> > > > the "list" argument.
> > >
> > > Ack. Will do a v2 if Mel feels it's appropriate to remove at this stage,
> > > otherwise we can drop the idea and wait for users to emerge.
> >
> > I reckon we should give it another few months until May. There has been
> > one user recently that tried to use list but it turned out arrays were
> > more appropriate.
> 
> Another recent try was the patches for dm-crypt. However Mel suggested
> adding a callback interface instead of using list since list is not
> necessary for that usecase. Or are we talking about the same one?
> 

That was the one I was thinking of but forgot the specifics so the array
comment was wrong. I only remembered that there was an attempted list user
but it wasn't the best solution.

> I didn't get time to implement Mel's suggestion yet due to my
> employment change. Hopefully I can find some time after the new year.
> 

No rush.

-- 
Mel Gorman
SUSE Labs

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Lorenzo Stoakes]

On Mon, 19 Dec 2022 at 10:07, Mel Gorman <mgorman@techsingularity.net> wrote:
>
> On Sat, Dec 17, 2022 at 08:34:58AM +0000, Lorenzo Stoakes wrote:
> I reckon we should give it another few months until May. There has been
> one user recently that tried to use list but it turned out arrays were
> more appropriate.
>

It being May 31st, it feels appropriate to chase this up :)

David's series at [0] did initially use this function, before
switching to the _array() variant. Other than that it seems that it
remains unused.

Cheers, Lorenzo

[0]:https://lore.kernel.org/all/20230522205744.2825689-1-dhowells@redhat.com/

> --
> Mel Gorman
> SUSE Labs



-- 
Lorenzo Stoakes
https://ljs.io

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Christoph Hellwig]

On Sat, Dec 17, 2022 at 04:56:03AM +0000, Matthew Wilcox wrote:
> On Sat, Dec 17, 2022 at 12:15:54AM +0000, Lorenzo Stoakes wrote:
> > This function is not referenced anywhere else in the kernel, remove it.
> 
> I think we're waiting to see if any users show up.  It's only been 18
> months or so, so perhaps wait a little longer?

Is that being snarky? :)  We generally don't add dead code at all, and
certaintly don't leave it around for a year and a half.

If anyone really needs this we can add it back.

> Also, if we do get rid of this, then __alloc_pages_bulk() can lose
> the "list" argument.

Yepp.

Re: [PATCH] mm: remove unused alloc_pages_bulk_list()

[Lorenzo Stoakes]

On Thu, Dec 22, 2022 at 02:03:46AM -0800, Christoph Hellwig wrote:
> Is that being snarky? :)  We generally don't add dead code at all, and
> certaintly don't leave it around for a year and a half.
>
> If anyone really needs this we can add it back.
>

Mel has replied elsewhere on this thread and we have a potential user so I think
the lowest-impact approach is to go with what he suggested - wait until May and
see if we have any takers.

I have put a reminder in my calendar for then, I'll check to see if it's being
used anywhere, if not I'll respin this patch. So problem solved for everyone :)

> > Also, if we do get rid of this, then __alloc_pages_bulk() can lose
> > the "list" argument.
>
> Yepp.

Yeah the respin will take this into account, if the function remains unused in
May.