[PATCH V2] mm/khugepaged: fix comment for default scan sleep duration

[PATCH V2] mm/khugepaged: fix comment for default scan sleep duration

[wang lian]

The comment for khugepaged_scan_sleep_millisecs incorrectly states
the default scan period is 30 seconds. The actual default value in the
code is 10000ms (10 seconds).

This patch corrects the comment to match the code, preventing potential
confusion. The incorrect comment has existed since the feature was
first introduced.

Fixes: ba76149f47d8 ("thp: khugepaged")

Signed-off-by: wang lian <lianux.mm@gmail.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
---
 mm/khugepaged.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index e947b96e1443..d635d821f611 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -67,7 +67,7 @@ enum scan_result {
 static struct task_struct *khugepaged_thread __read_mostly;
 static DEFINE_MUTEX(khugepaged_mutex);
 
-/* default scan 8*512 pte (or vmas) every 30 second */
+/* default scan 8*HPAGE_PMD_NR ptes (or vmas) every 10 second */
 static unsigned int khugepaged_pages_to_scan __read_mostly;
 static unsigned int khugepaged_pages_collapsed;
 static unsigned int khugepaged_full_scans;
-- 
2.50.1 (Apple Git-155)

Re: [PATCH V2] mm/khugepaged: fix comment for default scan sleep duration

[David Hildenbrand]

On 15.10.25 11:29, wang lian wrote:
> The comment for khugepaged_scan_sleep_millisecs incorrectly states
> the default scan period is 30 seconds. The actual default value in the
> code is 10000ms (10 seconds).
> 
> This patch corrects the comment to match the code, preventing potential
> confusion. The incorrect comment has existed since the feature was
> first introduced.

"While at it, replace the magic value 512 by HPAGE_PMD_NR and use 'ptes'."

> 
> Fixes: ba76149f47d8 ("thp: khugepaged")

I prefer to not have fixes for comments. It tricks people into thinking 
that this might warrant a backport.

Likely no need to resend and Andrew can fix it up when applying.

Acked-by: David Hildenbrand <david@redhat.com>


-- 
Cheers

David / dhildenb

Re: [PATCH V2] mm/khugepaged: fix comment for default scan sleep duration

[wang lian]

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Ok, I get it, thanks.

> On Oct 15, 2025, at 17:38, David Hildenbrand <david@redhat.com> wrote:
> 
> "While at it, replace the magic value 512 by HPAGE_PMD_NR and use 'ptes'."
> 
>> Fixes: ba76149f47d8 ("thp: khugepaged")
> 
> I prefer to not have fixes for comments. It tricks people into thinking that this might warrant a backport.
> 
> Likely no need to resend and Andrew can fix it up when applying.


--
Best Regards,
wang lian

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Re: [PATCH V2] mm/khugepaged: fix comment for default scan sleep duration

[SeongJae Park]

On Wed, 15 Oct 2025 17:29:57 +0800 wang lian <lianux.mm@gmail.com> wrote:

> The comment for khugepaged_scan_sleep_millisecs incorrectly states
> the default scan period is 30 seconds. The actual default value in the
> code is 10000ms (10 seconds).
> 
> This patch corrects the comment to match the code, preventing potential
> confusion. The incorrect comment has existed since the feature was
> first introduced.
> 
> Fixes: ba76149f47d8 ("thp: khugepaged")
> 
> Signed-off-by: wang lian <lianux.mm@gmail.com>
> Suggested-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Dev Jain <dev.jain@arm.com>
> Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
> Reviewed-by: Lance Yang <lance.yang@linux.dev>

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


Thanks,
SJ

[...]

Re: [PATCH V2] mm/khugepaged: fix comment for default scan sleep duration

[Vishal Moola (Oracle)]

On Wed, Oct 15, 2025 at 05:29:57PM +0800, wang lian wrote:
> The comment for khugepaged_scan_sleep_millisecs incorrectly states
> the default scan period is 30 seconds. The actual default value in the
> code is 10000ms (10 seconds).
> 
> This patch corrects the comment to match the code, preventing potential
> confusion. The incorrect comment has existed since the feature was
> first introduced.
> 
> Fixes: ba76149f47d8 ("thp: khugepaged")
> 
> Signed-off-by: wang lian <lianux.mm@gmail.com>
> Suggested-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Dev Jain <dev.jain@arm.com>
> Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
> Reviewed-by: Lance Yang <lance.yang@linux.dev>
> ---

Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>

Re: [V2] mm/khugepaged: fix comment for default scan sleep duration

[Nico Pache]

> The comment for khugepaged_scan_sleep_millisecs incorrectly states
> the default scan period is 30 seconds. The actual default value in the
> code is 10000ms (10 seconds).
> 
> This patch corrects the comment to match the code, preventing potential
> confusion. The incorrect comment has existed since the feature was
> first introduced.
> 
> Fixes: ba76149f47d8 ("thp: khugepaged")
> 
> Signed-off-by: wang lian <lianux.mm@gmail.com>
> Suggested-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Dev Jain <dev.jain@arm.com>
> Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
> Reviewed-by: Lance Yang <lance.yang@linux.dev>

Nice cleanup for the comments!

Acked-by: Nico Pache <npache@redhat.com>
> ---
>  mm/khugepaged.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index e947b96e1443..d635d821f611 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -67,7 +67,7 @@ enum scan_result {
>  static struct task_struct *khugepaged_thread __read_mostly;
>  static DEFINE_MUTEX(khugepaged_mutex);
>  
> -/* default scan 8*512 pte (or vmas) every 30 second */
> +/* default scan 8*HPAGE_PMD_NR ptes (or vmas) every 10 second */
>  static unsigned int khugepaged_pages_to_scan __read_mostly;
>  static unsigned int khugepaged_pages_collapsed;
>  static unsigned int khugepaged_full_scans;
>