linux-kernel - Re: [PATCH] zram: remove zcomp_stream_put() from write_incompressible

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Message-Id: <20250115152837.b9f721bccfd07ce903fc4539@linux-foundation.org>
Date: Wed, 15 Jan 2025 15:28:37 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Minchan Kim <minchan@...nel.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] zram: remove zcomp_stream_put() from
 write_incompressible_page()

On Wed, 15 Jan 2025 16:19:16 +0900 Sergey Senozhatsky <senozhatsky@...omium.org> wrote:

> We cannot and should not put per-CPU compression stream in
> write_incompressible_page() because that function never gets any
> per-CPU streams in the first place.  It's zram_write_page() that
> puts the stream before it calls write_incompressible_page().
> 
> ...
>
> +++ b/drivers/block/zram/zram_drv.c
> @@ -1683,7 +1683,6 @@ static int write_incompressible_page(struct zram *zram, struct page *page,
>  		return PTR_ERR((void *)handle);
>  
>  	if (!zram_can_store_page(zram)) {
> -		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
>  		zs_free(zram->mem_pool, handle);
>  		return -ENOMEM;
>  	}

I added

Fixes: 485d11509d6d ("zram: factor out ZRAM_HUGE write")

That way, anyone who backports 485d11509d6d into their earlier kernel
will have a better chance of noticing that they need this fixup.