diff mbox series

[05/11] mm: page_vma_mapped_walk(): prettify PVMW_MIGRATION block

Message ID 378c8650-1488-2edf-9647-32a53cf2e21@google.com (mailing list archive)
State New
Headers show
Series mm: page_vma_mapped_walk() cleanup and THP fixes | expand

Commit Message

Hugh Dickins June 10, 2021, 6:42 a.m. UTC
page_vma_mapped_walk() cleanup: rearrange the !pmd_present() block to
follow the same "return not_found, return not_found, return true" pattern
as the block above it (note: returning not_found there is never premature,
since existence or prior existence of huge pmd guarantees good alignment).

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
---
 mm/page_vma_mapped.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

Comments

Kirill A. Shutemov June 10, 2021, 9:16 a.m. UTC | #1
On Wed, Jun 09, 2021 at 11:42:12PM -0700, Hugh Dickins wrote:
> page_vma_mapped_walk() cleanup: rearrange the !pmd_present() block to
> follow the same "return not_found, return not_found, return true" pattern
> as the block above it (note: returning not_found there is never premature,
> since existence or prior existence of huge pmd guarantees good alignment).
> 
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Cc: <stable@vger.kernel.org>

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Peter Xu June 10, 2021, 2:48 p.m. UTC | #2
On Wed, Jun 09, 2021 at 11:42:12PM -0700, Hugh Dickins wrote:
> page_vma_mapped_walk() cleanup: rearrange the !pmd_present() block to
> follow the same "return not_found, return not_found, return true" pattern
> as the block above it (note: returning not_found there is never premature,
> since existence or prior existence of huge pmd guarantees good alignment).
> 
> Signed-off-by: Hugh Dickins <hughd@google.com>
> Cc: <stable@vger.kernel.org>
> ---
>  mm/page_vma_mapped.c | 30 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index 81000dd0b5da..b96fae568bc2 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -201,24 +201,22 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
>  			if (pmd_page(pmde) != page)
>  				return not_found(pvmw);
>  			return true;
> -		} else if (!pmd_present(pmde)) {
> -			if (thp_migration_supported()) {
> -				if (!(pvmw->flags & PVMW_MIGRATION))
> -					return not_found(pvmw);
> -				if (is_migration_entry(pmd_to_swp_entry(pmde))) {
> -					swp_entry_t entry = pmd_to_swp_entry(pmde);
> +		}
> +		if (!pmd_present(pmde)) {
> +			swp_entry_t entry;
>  
> -					if (migration_entry_to_page(entry) != page)
> -						return not_found(pvmw);
> -					return true;
> -				}
> -			}
> -			return not_found(pvmw);
> -		} else {
> -			/* THP pmd was split under us: handle on pte level */
> -			spin_unlock(pvmw->ptl);
> -			pvmw->ptl = NULL;
> +			if (!thp_migration_supported() ||
> +			    !(pvmw->flags & PVMW_MIGRATION))
> +				return not_found(pvmw);
> +			entry = pmd_to_swp_entry(pmde);
> +			if (!is_migration_entry(entry) ||
> +			    migration_entry_to_page(entry) != page)

We'll need to do s/migration_entry_to_page/pfn_swap_entry_to_page/, depending
on whether Alistair's series lands first or not I guess (as you mentioned in
the cover letter).

Thanks for the change, it does look much better.

Reviewed-by: Peter Xu <peterx@redhat.com>

> +				return not_found(pvmw);
> +			return true;
>  		}
> +		/* THP pmd was split under us: handle on pte level */
> +		spin_unlock(pvmw->ptl);
> +		pvmw->ptl = NULL;
>  	} else if (!pmd_present(pmde)) {
>  		/*
>  		 * If PVMW_SYNC, take and drop THP pmd lock so that we
> -- 
> 2.26.2
>
diff mbox series

Patch

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 81000dd0b5da..b96fae568bc2 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -201,24 +201,22 @@  bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 			if (pmd_page(pmde) != page)
 				return not_found(pvmw);
 			return true;
-		} else if (!pmd_present(pmde)) {
-			if (thp_migration_supported()) {
-				if (!(pvmw->flags & PVMW_MIGRATION))
-					return not_found(pvmw);
-				if (is_migration_entry(pmd_to_swp_entry(pmde))) {
-					swp_entry_t entry = pmd_to_swp_entry(pmde);
+		}
+		if (!pmd_present(pmde)) {
+			swp_entry_t entry;
 
-					if (migration_entry_to_page(entry) != page)
-						return not_found(pvmw);
-					return true;
-				}
-			}
-			return not_found(pvmw);
-		} else {
-			/* THP pmd was split under us: handle on pte level */
-			spin_unlock(pvmw->ptl);
-			pvmw->ptl = NULL;
+			if (!thp_migration_supported() ||
+			    !(pvmw->flags & PVMW_MIGRATION))
+				return not_found(pvmw);
+			entry = pmd_to_swp_entry(pmde);
+			if (!is_migration_entry(entry) ||
+			    migration_entry_to_page(entry) != page)
+				return not_found(pvmw);
+			return true;
 		}
+		/* THP pmd was split under us: handle on pte level */
+		spin_unlock(pvmw->ptl);
+		pvmw->ptl = NULL;
 	} else if (!pmd_present(pmde)) {
 		/*
 		 * If PVMW_SYNC, take and drop THP pmd lock so that we