* [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings
@ 2026-04-19 17:47 Sunny Patel
2026-04-19 17:50 ` Zi Yan
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Sunny Patel @ 2026-04-19 17:47 UTC (permalink / raw)
To: Andrew Morton, David Hildenbrand
Cc: Zi Yan, Matthew Brost, Joshua Hahn, Rakie Kim, Byungchul Park,
Gregory Price, Ying Huang, Alistair Popple, linux-mm,
linux-kernel, Sunny Patel
Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it
with a simpler VM_WARN_ON_ONCE(!folio) check.
Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) &&
!is_huge_zero_pmd(*pmdp)).
Refactor the PMD checks, making the control flow
clearer and avoiding duplicate condition checks.
Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
---
Changes in v2:
- Removed additional check for pmd_present() as is_huge_zero_pmd()
already checks for pmd_present().
Missed it in first version of this patch.
mm/migrate_device.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 8079676c8f1f..2c7e89a6d1b1 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -807,8 +807,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
bool flush = false;
unsigned long i;
- VM_WARN_ON_FOLIO(!folio, folio);
- VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp));
+ VM_WARN_ON_ONCE(!folio);
if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER))
return -EINVAL;
@@ -865,11 +864,9 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
if (userfaultfd_missing(vma))
goto unlock_abort;
- if (!pmd_none(*pmdp)) {
- if (!is_huge_zero_pmd(*pmdp))
- goto unlock_abort;
+ if (is_huge_zero_pmd(*pmdp))
flush = true;
- } else if (!pmd_none(*pmdp))
+ else if (!pmd_none(*pmdp))
goto unlock_abort;
add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
--
2.43.0
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings
2026-04-19 17:47 [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings Sunny Patel
@ 2026-04-19 17:50 ` Zi Yan
2026-04-20 8:01 ` Huang, Ying
2026-04-20 19:33 ` David Hildenbrand (Arm)
2 siblings, 0 replies; 4+ messages in thread
From: Zi Yan @ 2026-04-19 17:50 UTC (permalink / raw)
To: Sunny Patel
Cc: Andrew Morton, David Hildenbrand, Matthew Brost, Joshua Hahn,
Rakie Kim, Byungchul Park, Gregory Price, Ying Huang,
Alistair Popple, linux-mm, linux-kernel
On 19 Apr 2026, at 13:47, Sunny Patel wrote:
> Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it
> with a simpler VM_WARN_ON_ONCE(!folio) check.
>
> Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) &&
> !is_huge_zero_pmd(*pmdp)).
>
> Refactor the PMD checks, making the control flow
> clearer and avoiding duplicate condition checks.
>
> Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
> ---
>
> Changes in v2:
> - Removed additional check for pmd_present() as is_huge_zero_pmd()
> already checks for pmd_present().
>
> Missed it in first version of this patch.
>
> mm/migrate_device.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
LGTM.
Acked-by: Zi Yan <ziy@nvidia.com>
--
Best Regards,
Yan, Zi
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings
2026-04-19 17:47 [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings Sunny Patel
2026-04-19 17:50 ` Zi Yan
@ 2026-04-20 8:01 ` Huang, Ying
2026-04-20 19:33 ` David Hildenbrand (Arm)
2 siblings, 0 replies; 4+ messages in thread
From: Huang, Ying @ 2026-04-20 8:01 UTC (permalink / raw)
To: Sunny Patel
Cc: Andrew Morton, David Hildenbrand, Zi Yan, Matthew Brost,
Joshua Hahn, Rakie Kim, Byungchul Park, Gregory Price,
Alistair Popple, linux-mm, linux-kernel
Sunny Patel <nueralspacetech@gmail.com> writes:
> Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it
> with a simpler VM_WARN_ON_ONCE(!folio) check.
>
> Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) &&
> !is_huge_zero_pmd(*pmdp)).
>
> Refactor the PMD checks, making the control flow
> clearer and avoiding duplicate condition checks.
>
> Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
> ---
>
> Changes in v2:
> - Removed additional check for pmd_present() as is_huge_zero_pmd()
> already checks for pmd_present().
>
> Missed it in first version of this patch.
>
> mm/migrate_device.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index 8079676c8f1f..2c7e89a6d1b1 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -807,8 +807,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
> bool flush = false;
> unsigned long i;
>
> - VM_WARN_ON_FOLIO(!folio, folio);
> - VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp));
> + VM_WARN_ON_ONCE(!folio);
>
> if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER))
> return -EINVAL;
> @@ -865,11 +864,9 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate,
> if (userfaultfd_missing(vma))
> goto unlock_abort;
>
> - if (!pmd_none(*pmdp)) {
> - if (!is_huge_zero_pmd(*pmdp))
> - goto unlock_abort;
> + if (is_huge_zero_pmd(*pmdp))
> flush = true;
> - } else if (!pmd_none(*pmdp))
> + else if (!pmd_none(*pmdp))
> goto unlock_abort;
>
> add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR);
LGTM, feel free to add my
Reviewed-by: Huang Ying <ying.huang@linux.alibaba.com>
in the future versions.
---
Best Regards,
Huang, Ying
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings
2026-04-19 17:47 [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings Sunny Patel
2026-04-19 17:50 ` Zi Yan
2026-04-20 8:01 ` Huang, Ying
@ 2026-04-20 19:33 ` David Hildenbrand (Arm)
2 siblings, 0 replies; 4+ messages in thread
From: David Hildenbrand (Arm) @ 2026-04-20 19:33 UTC (permalink / raw)
To: Sunny Patel, Andrew Morton
Cc: Zi Yan, Matthew Brost, Joshua Hahn, Rakie Kim, Byungchul Park,
Gregory Price, Ying Huang, Alistair Popple, linux-mm,
linux-kernel
On 4/19/26 19:47, Sunny Patel wrote:
> Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it
> with a simpler VM_WARN_ON_ONCE(!folio) check.
>
> Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) &&
> !is_huge_zero_pmd(*pmdp)).
>
> Refactor the PMD checks, making the control flow
> clearer and avoiding duplicate condition checks.
>
> Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
> ---
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
^ permalink raw reply [flat|nested] 4+ messages in thread
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2026-04-19 17:47 [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings Sunny Patel
2026-04-19 17:50 ` Zi Yan
2026-04-20 8:01 ` Huang, Ying
2026-04-20 19:33 ` David Hildenbrand (Arm)
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