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[v1] zsmalloc: zs_destroy_pool: add size_class NULL check

Message ID 20221013112825.61869-1-avromanov@sberdevices.ru
State New
Headers
Series [v1] zsmalloc: zs_destroy_pool: add size_class NULL check |

Commit Message

Alexey Romanov Oct. 13, 2022, 11:28 a.m. UTC 
  Inside the zs_destroy_pool() function, there can still
be NULL size_class pointers: if when the next size_class is
allocated, inside zs_create_pool() function, kzalloc will
return NULL and handling the error condition, zs_create_pool()
will call zs_destroy_pool().

Fixes: f24263a5a076 ("zsmalloc: remove unnecessary size_class NULL check")
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
---
 mm/zsmalloc.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Sergey Senozhatsky Oct. 13, 2022, 12:34 p.m. UTC | #1 
On (22/10/13 14:28), Alexey Romanov wrote:
> Inside the zs_destroy_pool() function, there can still
> be NULL size_class pointers: if when the next size_class is
> allocated, inside zs_create_pool() function, kzalloc will
> return NULL and handling the error condition, zs_create_pool()
> will call zs_destroy_pool().
> 
> Fixes: f24263a5a076 ("zsmalloc: remove unnecessary size_class NULL check")
> Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
> ---
>  mm/zsmalloc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 525758713a55..d03941cace2c 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -2311,6 +2311,9 @@ void zs_destroy_pool(struct zs_pool *pool)
>  		int fg;
>  		struct size_class *class = pool->size_class[i];
>  
> +		if (!class)
> +			continue;
> +
>  		if (class->index != i)
>  			continue;

Yeah, OK... And totally my fault! I think, I, personally, am done
with the "remove if" patches at this point, they are too painful.

Alexey, is there anything else we missed?

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

Andrew,
The allocation in question should be of a "too small to fail"
size, below PAGE_ALLOC_COSTLY_ORDER. So unless that unspoken
rule has changed, we should be "fine", since that kmalloc()
simply should not fail. It still makes sense to have that
particular check in place, just in case. Can you please pull
this patch in? And, like I said, I'm going to NAK all future
micro-optimizations.
diff mbox series

Patch

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 525758713a55..d03941cace2c 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -2311,6 +2311,9 @@  void zs_destroy_pool(struct zs_pool *pool)
 		int fg;
 		struct size_class *class = pool->size_class[i];
 
+		if (!class)
+			continue;
+
 		if (class->index != i)
 			continue;