[PATCH 0/3] mm: Coccinelle-driven cleanups across memory management code

[PATCH 0/3] mm: Coccinelle-driven cleanups across memory management code

[Sahil Chandna]

This patch series contains three minor cleanups identified by
Coccinelle scripts under scripts/coccinelle/misc/:

  * Replace manual ternary expression with the min() macro in pagewalk.c
  * Use the %pe printk format specifier for PTR_ERR() reporting
    in vmscan.c and zswap.c
Found using:
  make coccicheck MODE=report M=mm/

Sahil Chandna (3):
  mm/pagewalk: use min() macro instead of manual ternary
  mm/vmscan: use %pe to print PTR_ERR() values
  mm/zswap: use %pe to print PTR_ERR() values

 mm/pagewalk.c | 2 +-
 mm/vmscan.c   | 4 ++--
 mm/zswap.c    | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

-- 
2.50.1

[PATCH 1/3] mm/pagewalk: use min() macro instead of manual ternary

[Sahil Chandna]

 mm: pagewalk: use min() macro instead of manual ternary expression

Use the kernel-provided min() macro to compute the minimum value instead
of an explicit ternary expression. This improves readability and matches
common kernel style.

This was flagged by Coccinelle
(misc/minmax.cocci) as an opportunity to use min().

Found by: make coccicheck MODE=report M=mm/
No functional change intended.

Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>
---
 mm/pagewalk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 9f91cf85a5be..82db421b5b34 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -313,7 +313,7 @@ static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
 				       unsigned long end)
 {
 	unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
-	return boundary < end ? boundary : end;
+	return min(boundary, end);
 }
 
 static int walk_hugetlb_range(unsigned long addr, unsigned long end,
-- 
2.50.1

[PATCH 2/3] mm/vmscan: use %pe to print PTR_ERR() values

[Sahil Chandna]

Use the %pe printk format specifier to report error pointers directly
instead of printing PTR_ERR() as a long value. This improves clarity,
produces more readable error messages.

This instance was flagged by the Coccinelle script
(misc/ptr_err_to_pe.cocci) as an opportunity to adopt %pe.

Found by: make coccicheck MODE=report M=mm/
No functional change intended

Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index b2fc8b626d3d..7d5b41696cc3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -7500,8 +7500,8 @@ void __meminit kswapd_run(int nid)
 		pgdat->kswapd = kthread_create_on_node(kswapd, pgdat, nid, "kswapd%d", nid);
 		if (IS_ERR(pgdat->kswapd)) {
 			/* failure at boot is fatal */
-			pr_err("Failed to start kswapd on node %d,ret=%ld\n",
-				   nid, PTR_ERR(pgdat->kswapd));
+			pr_err("Failed to start kswapd on node %d,ret=%pe\n",
+				   nid, pgdat->kswapd);
 			BUG_ON(system_state < SYSTEM_RUNNING);
 			pgdat->kswapd = NULL;
 		} else {
-- 
2.50.1

[PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[Sahil Chandna]

Use the %pe printk format specifier to report error pointers directly
instead of printing PTR_ERR() as a long value. This improves clarity,
produces more readable error messages.

This instance was flagged by the Coccinelle script
(misc/ptr_err_to_pe.cocci) as an opportunity to adopt %pe.

Found by: make coccicheck MODE=report M=mm/
No functional change intended.

Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>
---
 mm/zswap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/zswap.c b/mm/zswap.c
index c1af782e54ec..c35604db32ad 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -749,8 +749,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
 
 	acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
 	if (IS_ERR(acomp)) {
-		pr_err("could not alloc crypto acomp %s : %ld\n",
-				pool->tfm_name, PTR_ERR(acomp));
+		pr_err("could not alloc crypto acomp %s : %pe\n",
+				pool->tfm_name, acomp);
 		ret = PTR_ERR(acomp);
 		goto fail;
 	}
-- 
2.50.1

Re: [PATCH 1/3] mm/pagewalk: use min() macro instead of manual ternary

[Markus Elfring]

>  mm: pagewalk: use min() macro instead of manual ternary expression

How do you think about to avoid the repetition of a patch subject
in the change description?


…
> This was flagged by Coccinelle
> (misc/minmax.cocci) as an opportunity to use min().

Would an other word wrapping be a bit nicer?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.18-rc6#n658

Regards,
Markus

Re: [PATCH 1/3] mm/pagewalk: use min() macro instead of manual ternary

[David Laight]

On Tue, 18 Nov 2025 11:38:49 +0530
Sahil Chandna <chandna.sahil@gmail.com> wrote:

>  mm: pagewalk: use min() macro instead of manual ternary expression
> 
> Use the kernel-provided min() macro to compute the minimum value instead
> of an explicit ternary expression. This improves readability and matches
> common kernel style.
> 
> This was flagged by Coccinelle
> (misc/minmax.cocci) as an opportunity to use min().
> 
> Found by: make coccicheck MODE=report M=mm/
> No functional change intended.
> 
> Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>
> ---
>  mm/pagewalk.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/pagewalk.c b/mm/pagewalk.c
> index 9f91cf85a5be..82db421b5b34 100644
> --- a/mm/pagewalk.c
> +++ b/mm/pagewalk.c
> @@ -313,7 +313,7 @@ static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
>  				       unsigned long end)
>  {
>  	unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
> -	return boundary < end ? boundary : end;
> +	return min(boundary, end);

You can remove the temporary:
	return min((addr & huge_page_mask(h)) + huge_page_size(h), end);

  David

>  }
>  
>  static int walk_hugetlb_range(unsigned long addr, unsigned long end,

Re: [PATCH 2/3] mm/vmscan: use %pe to print PTR_ERR() values

[Markus Elfring]

…
> +++ b/mm/vmscan.c
> @@ -7500,8 +7500,8 @@ void __meminit kswapd_run(int nid)
>  		pgdat->kswapd = kthread_create_on_node(kswapd, pgdat, nid, "kswapd%d", nid);
>  		if (IS_ERR(pgdat->kswapd)) {
…
> +			pr_err("Failed to start kswapd on node %d,ret=%pe\n",
> +				   nid, pgdat->kswapd);
>  			BUG_ON(system_state < SYSTEM_RUNNING);
…

I propose to adjust the indentation for the passed parameters.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.18-rc6#n110

Regards,
Markus

Re: [PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[Markus Elfring]

…
> +++ b/mm/zswap.c
> @@ -749,8 +749,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
>  
>  	acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
>  	if (IS_ERR(acomp)) {
…
> +		pr_err("could not alloc crypto acomp %s : %pe\n",
> +				pool->tfm_name, acomp);
>  		ret = PTR_ERR(acomp);
…

Would you like to reduce the indentation for the passed parameters?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.18-rc6#n110

Regards,
Markus

Re: [PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[Matthew Wilcox]

On Tue, Nov 18, 2025 at 02:20:59PM +0100, Markus Elfring wrote:
> …
> > +++ b/mm/zswap.c
> > @@ -749,8 +749,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
> >  
> >  	acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
> >  	if (IS_ERR(acomp)) {
> …
> > +		pr_err("could not alloc crypto acomp %s : %pe\n",
> > +				pool->tfm_name, acomp);
> >  		ret = PTR_ERR(acomp);
> …
> 
> Would you like to reduce the indentation for the passed parameters?
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.18-rc6#n110

That is the exact opposite of what this suggestion is intended to say.

Sahil, you should ignore any suggestion made to you by Markus.  He has
been told many times to stop making these useless and unhelpful comments,
and yet he persists.

Re: [PATCH 1/3] mm/pagewalk: use min() macro instead of manual ternary

[Matthew Wilcox]

On Tue, Nov 18, 2025 at 10:45:37AM +0000, David Laight wrote:
> On Tue, 18 Nov 2025 11:38:49 +0530
> Sahil Chandna <chandna.sahil@gmail.com> wrote:
> > +++ b/mm/pagewalk.c
> > @@ -313,7 +313,7 @@ static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
> >  				       unsigned long end)
> >  {
> >  	unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
> > -	return boundary < end ? boundary : end;
> > +	return min(boundary, end);
> 
> You can remove the temporary:
> 	return min((addr & huge_page_mask(h)) + huge_page_size(h), end);

You can, but I'm not sure that's better.  What would be better is:

	unsigned long boundary = (addr | ~huge_page_mask(h)) + 1;
	return min(boundary, end);

if you insist, we could do:

	return min((addr | ~huge_page_mask(h)) + 1, end);

Re: [PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[Yosry Ahmed]

On Tue, Nov 18, 2025 at 11:38:51AM +0530, Sahil Chandna wrote:
> Use the %pe printk format specifier to report error pointers directly
> instead of printing PTR_ERR() as a long value. This improves clarity,
> produces more readable error messages.
> 
> This instance was flagged by the Coccinelle script
> (misc/ptr_err_to_pe.cocci) as an opportunity to adopt %pe.
> 
> Found by: make coccicheck MODE=report M=mm/
> No functional change intended.
> 
> Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>

Acked-by: Yosry Ahmed <yosry.ahmed@linux.dev>

> ---
>  mm/zswap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/zswap.c b/mm/zswap.c
> index c1af782e54ec..c35604db32ad 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -749,8 +749,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
>  
>  	acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
>  	if (IS_ERR(acomp)) {
> -		pr_err("could not alloc crypto acomp %s : %ld\n",
> -				pool->tfm_name, PTR_ERR(acomp));
> +		pr_err("could not alloc crypto acomp %s : %pe\n",
> +				pool->tfm_name, acomp);
>  		ret = PTR_ERR(acomp);
>  		goto fail;
>  	}
> -- 
> 2.50.1
> 

Re: [PATCH 1/3] mm/pagewalk: use min() macro instead of manual ternary

[David Laight]

On Tue, 18 Nov 2025 15:18:50 +0000
Matthew Wilcox <willy@infradead.org> wrote:

> On Tue, Nov 18, 2025 at 10:45:37AM +0000, David Laight wrote:
> > On Tue, 18 Nov 2025 11:38:49 +0530
> > Sahil Chandna <chandna.sahil@gmail.com> wrote:  
> > > +++ b/mm/pagewalk.c
> > > @@ -313,7 +313,7 @@ static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
> > >  				       unsigned long end)
> > >  {
> > >  	unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
> > > -	return boundary < end ? boundary : end;
> > > +	return min(boundary, end);  
> > 
> > You can remove the temporary:
> > 	return min((addr & huge_page_mask(h)) + huge_page_size(h), end);  
> 
> You can, but I'm not sure that's better.  What would be better is:
> 
> 	unsigned long boundary = (addr | ~huge_page_mask(h)) + 1;
> 	return min(boundary, end);
> 
> if you insist, we could do:
> 
> 	return min((addr | ~huge_page_mask(h)) + 1, end);

Indeed...

	David

Re: [PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[Markus Elfring]

>>> +++ b/mm/zswap.c
>>> @@ -749,8 +749,8 @@ static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
>>>  
>>>  	acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
>>>  	if (IS_ERR(acomp)) {
>> …
>>> +		pr_err("could not alloc crypto acomp %s : %pe\n",
>>> +				pool->tfm_name, acomp);
>>>  		ret = PTR_ERR(acomp);
>> …
>>
>> Would you like to reduce the indentation for the passed parameters?
>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?h=v6.18-rc6#n110
> 
> That is the exact opposite of what this suggestion is intended to say.

I wonder about the interpretation of the provided information in such a direction.


> Sahil, you should ignore any suggestion made to you by Markus.

Do you try to distract from reminders according to a known information source here?

Regards,
Markus

Re: [PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[SeongJae Park]

On Tue, 18 Nov 2025 11:38:51 +0530 Sahil Chandna <chandna.sahil@gmail.com> wrote:

> Use the %pe printk format specifier to report error pointers directly
> instead of printing PTR_ERR() as a long value. This improves clarity,
> produces more readable error messages.
> 
> This instance was flagged by the Coccinelle script
> (misc/ptr_err_to_pe.cocci) as an opportunity to adopt %pe.
> 
> Found by: make coccicheck MODE=report M=mm/
> No functional change intended.
> 
> Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH 2/3] mm/vmscan: use %pe to print PTR_ERR() values

[SeongJae Park]

On Tue, 18 Nov 2025 11:38:50 +0530 Sahil Chandna <chandna.sahil@gmail.com> wrote:

> Use the %pe printk format specifier to report error pointers directly
> instead of printing PTR_ERR() as a long value. This improves clarity,
> produces more readable error messages.
> 
> This instance was flagged by the Coccinelle script
> (misc/ptr_err_to_pe.cocci) as an opportunity to adopt %pe.
> 
> Found by: make coccicheck MODE=report M=mm/
> No functional change intended
> 
> Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

[...]

Re: [PATCH 3/3] mm/zswap: use %pe to print PTR_ERR() values

[Nhat Pham]

On Tue, Nov 18, 2025 at 6:09 AM Sahil Chandna <chandna.sahil@gmail.com> wrote:
>
> Use the %pe printk format specifier to report error pointers directly
> instead of printing PTR_ERR() as a long value. This improves clarity,
> produces more readable error messages.
>
> This instance was flagged by the Coccinelle script
> (misc/ptr_err_to_pe.cocci) as an opportunity to adopt %pe.
>
> Found by: make coccicheck MODE=report M=mm/
> No functional change intended.
>
> Signed-off-by: Sahil Chandna <chandna.sahil@gmail.com>

Acked-by: Nhat Pham <nphamcs@gmail.com>