+ zsmalloc-remove-unnecessary-size_class-null-check.patch added to mm-unstable branch

+ zsmalloc-remove-unnecessary-size_class-null-check.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: zsmalloc: remove unnecessary size_class NULL check
has been added to the -mm mm-unstable branch.  Its filename is
     zsmalloc-remove-unnecessary-size_class-null-check.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zsmalloc-remove-unnecessary-size_class-null-check.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Alexey Romanov <avromanov@sberdevices.ru>
Subject: zsmalloc: remove unnecessary size_class NULL check
Date: Thu, 11 Aug 2022 18:37:55 +0300

pool->size_class array elements can't be NULL, so this check
is not needed.

In the whole code, we assign pool->size_class[i] values that are
not NULL. Releasing memory for these values occurs in the
zs_destroy_pool() function, which also releases and destroys the pool.

In addition, in the zs_stats_size_show() and async_free_zspage(),
with similar iterations over the array, we don't check it for NULL
pointer.

Link: https://lkml.kernel.org/r/20220811153755.16102-3-avromanov@sberdevices.ru
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zsmalloc.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/mm/zsmalloc.c~zsmalloc-remove-unnecessary-size_class-null-check
+++ a/mm/zsmalloc.c
@@ -2110,8 +2110,6 @@ unsigned long zs_compact(struct zs_pool
 
 	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
 		class = pool->size_class[i];
-		if (!class)
-			continue;
 		if (class->index != i)
 			continue;
 		pages_freed += __zs_compact(pool, class);
@@ -2156,8 +2154,6 @@ static unsigned long zs_shrinker_count(s
 
 	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
 		class = pool->size_class[i];
-		if (!class)
-			continue;
 		if (class->index != i)
 			continue;
 
@@ -2315,9 +2311,6 @@ void zs_destroy_pool(struct zs_pool *poo
 		int fg;
 		struct size_class *class = pool->size_class[i];
 
-		if (!class)
-			continue;
-
 		if (class->index != i)
 			continue;
 
_

Patches currently in -mm which might be from avromanov@sberdevices.ru are

zsmalloc-zs_object_copy-add-clarifying-comment.patch
zsmalloc-remove-unnecessary-size_class-null-check.patch

Re: + zsmalloc-remove-unnecessary-size_class-null-check.patch added to mm-unstable branch

[Sergey Senozhatsky]

On (22/08/11 14:22), Andrew Morton wrote:
> pool->size_class array elements can't be NULL, so this check
> is not needed.
> 
> In the whole code, we assign pool->size_class[i] values that are
> not NULL. Releasing memory for these values occurs in the
> zs_destroy_pool() function, which also releases and destroys the pool.
> 
> In addition, in the zs_stats_size_show() and async_free_zspage(),
> with similar iterations over the array, we don't check it for NULL
> pointer.
> 
> Link: https://lkml.kernel.org/r/20220811153755.16102-3-avromanov@sberdevices.ru
> Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Nitin Gupta <ngupta@vflare.org>
> Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>