[PATCH 0/4] mm/zswap: misc cleanup of code and documentations

[PATCH 0/4] mm/zswap: misc cleanup of code and documentations

[SeongJae Park]

Cleanup an unnecessary local variable write in incompressible pages
handling, typos (s/zwap/zswap/) and outdated comments/documentations
about the zswap's red-black tree, which is replaced by xarray.

SeongJae Park (4):
  mm/zswap: remove unnecessary dlen writes for incompressible pages
  mm/zswap: fix typos: s/zwap/zswap/
  mm/zswap: s/red-black tree/xarray/
  Docs/admin-guide/mm/zswap: s/red-black tree/xarray/

 Documentation/admin-guide/mm/zswap.rst | 10 +++++-----
 mm/memcontrol.c                        |  2 +-
 mm/zswap.c                             |  7 +++----
 3 files changed, 9 insertions(+), 10 deletions(-)


base-commit: 2e943d9cc1fdd399a2f95d1c1d6b865d04bfa239
-- 
2.39.5

[PATCH 4/4] Docs/admin-guide/mm/zswap: s/red-black tree/xarray/

[SeongJae Park]

The change from commit 796c2c23e14e ("zswap: replace RB tree with
xarray") is not reflected on the document.  Update the document.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/zswap.rst | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
index 283d77217c6f..2464425c783d 100644
--- a/Documentation/admin-guide/mm/zswap.rst
+++ b/Documentation/admin-guide/mm/zswap.rst
@@ -59,11 +59,11 @@ returned by the allocation routine and that handle must be mapped before being
 accessed.  The compressed memory pool grows on demand and shrinks as compressed
 pages are freed.  The pool is not preallocated.
 
-When a swap page is passed from swapout to zswap, zswap maintains a mapping
-of the swap entry, a combination of the swap type and swap offset, to the
-zsmalloc handle that references that compressed swap page.  This mapping is
-achieved with a red-black tree per swap type.  The swap offset is the search
-key for the tree nodes.
+When a swap page is passed from swapout to zswap, zswap maintains a mapping of
+the swap entry, a combination of the swap type and swap offset, to the zsmalloc
+handle that references that compressed swap page.  This mapping is achieved
+with an xarray per swap type.  The swap offset is the search key for the xarray
+nodes.
 
 During a page fault on a PTE that is a swap entry, the swapin code calls the
 zswap load function to decompress the page into the page allocated by the page
-- 
2.39.5

Re: [PATCH 4/4] Docs/admin-guide/mm/zswap: s/red-black tree/xarray/

[Yosry Ahmed]

On Fri, Oct 03, 2025 at 01:38:51PM -0700, SeongJae Park wrote:
> The change from commit 796c2c23e14e ("zswap: replace RB tree with
> xarray") is not reflected on the document.  Update the document.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>

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

> ---
>  Documentation/admin-guide/mm/zswap.rst | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
> index 283d77217c6f..2464425c783d 100644
> --- a/Documentation/admin-guide/mm/zswap.rst
> +++ b/Documentation/admin-guide/mm/zswap.rst
> @@ -59,11 +59,11 @@ returned by the allocation routine and that handle must be mapped before being
>  accessed.  The compressed memory pool grows on demand and shrinks as compressed
>  pages are freed.  The pool is not preallocated.
>  
> -When a swap page is passed from swapout to zswap, zswap maintains a mapping
> -of the swap entry, a combination of the swap type and swap offset, to the
> -zsmalloc handle that references that compressed swap page.  This mapping is
> -achieved with a red-black tree per swap type.  The swap offset is the search
> -key for the tree nodes.
> +When a swap page is passed from swapout to zswap, zswap maintains a mapping of
> +the swap entry, a combination of the swap type and swap offset, to the zsmalloc
> +handle that references that compressed swap page.  This mapping is achieved
> +with an xarray per swap type.  The swap offset is the search key for the xarray
> +nodes.
>  
>  During a page fault on a PTE that is a swap entry, the swapin code calls the
>  zswap load function to decompress the page into the page allocated by the page
> -- 
> 2.39.5

Re: [PATCH 4/4] Docs/admin-guide/mm/zswap: s/red-black tree/xarray/

[Nhat Pham]

On Fri, Oct 3, 2025 at 1:38 PM SeongJae Park <sj@kernel.org> wrote:
>
> The change from commit 796c2c23e14e ("zswap: replace RB tree with
> xarray") is not reflected on the document.  Update the document.
>
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  Documentation/admin-guide/mm/zswap.rst | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
> index 283d77217c6f..2464425c783d 100644
> --- a/Documentation/admin-guide/mm/zswap.rst
> +++ b/Documentation/admin-guide/mm/zswap.rst
> @@ -59,11 +59,11 @@ returned by the allocation routine and that handle must be mapped before being
>  accessed.  The compressed memory pool grows on demand and shrinks as compressed
>  pages are freed.  The pool is not preallocated.
>
> -When a swap page is passed from swapout to zswap, zswap maintains a mapping
> -of the swap entry, a combination of the swap type and swap offset, to the
> -zsmalloc handle that references that compressed swap page.  This mapping is
> -achieved with a red-black tree per swap type.  The swap offset is the search
> -key for the tree nodes.
> +When a swap page is passed from swapout to zswap, zswap maintains a mapping of
> +the swap entry, a combination of the swap type and swap offset, to the zsmalloc
> +handle that references that compressed swap page.  This mapping is achieved
> +with an xarray per swap type.  The swap offset is the search key for the xarray
> +nodes.
>

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

Re: [PATCH 4/4] Docs/admin-guide/mm/zswap: s/red-black tree/xarray/

[Chengming Zhou]

On 2025/10/4 04:38, SeongJae Park wrote:
> The change from commit 796c2c23e14e ("zswap: replace RB tree with
> xarray") is not reflected on the document.  Update the document.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>

Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>

> ---
>   Documentation/admin-guide/mm/zswap.rst | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/admin-guide/mm/zswap.rst b/Documentation/admin-guide/mm/zswap.rst
> index 283d77217c6f..2464425c783d 100644
> --- a/Documentation/admin-guide/mm/zswap.rst
> +++ b/Documentation/admin-guide/mm/zswap.rst
> @@ -59,11 +59,11 @@ returned by the allocation routine and that handle must be mapped before being
>   accessed.  The compressed memory pool grows on demand and shrinks as compressed
>   pages are freed.  The pool is not preallocated.
>   
> -When a swap page is passed from swapout to zswap, zswap maintains a mapping
> -of the swap entry, a combination of the swap type and swap offset, to the
> -zsmalloc handle that references that compressed swap page.  This mapping is
> -achieved with a red-black tree per swap type.  The swap offset is the search
> -key for the tree nodes.
> +When a swap page is passed from swapout to zswap, zswap maintains a mapping of
> +the swap entry, a combination of the swap type and swap offset, to the zsmalloc
> +handle that references that compressed swap page.  This mapping is achieved
> +with an xarray per swap type.  The swap offset is the search key for the xarray
> +nodes.
>   
>   During a page fault on a PTE that is a swap entry, the swapin code calls the
>   zswap load function to decompress the page into the page allocated by the page