Re: [PATCH 5.15 1/3] drivers/block/zram/zram_drv.c: do not keep dangling zcomp pointer after zram reset

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 6d2453c3dbc5f70eafc1c866289a90a1fc57ce18

WARNING: Author mismatch between patch and upstream commit:
Backport author: Dominique Martinet<dominique.martinet@atmark-techno.com>
Commit author: Sergey Senozhatsky<senozhatsky@chromium.org>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (exact SHA1)
6.1.y | Present (exact SHA1)
5.15.y | Not found

Note: The patch differs from the upstream commit:
---
1:  6d2453c3dbc5 ! 1:  70169b5d17a5 drivers/block/zram/zram_drv.c: do not keep dangling zcomp pointer after zram reset
    @@ Metadata
      ## Commit message ##
         drivers/block/zram/zram_drv.c: do not keep dangling zcomp pointer after zram reset
     
    +    [ Upstream commit 6d2453c3dbc5f70eafc1c866289a90a1fc57ce18 ]
    +
         We do all reset operations under write lock, so we don't need to save
         ->disksize and ->comp to stack variables.  Another thing is that ->comp is
         freed during zram reset, but comp pointer is not NULL-ed, so zram keeps
    @@ Commit message
         Cc: Minchan Kim <minchan@kernel.org>
         Cc: Nitin Gupta <ngupta@vflare.org>
         Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    +    Stable-dep-of: 74363ec674cb ("zram: fix uninitialized ZRAM not releasing backing device")
    +    Signed-off-by: Sasha Levin <sashal@kernel.org>
    +    Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
     
      ## drivers/block/zram/zram_drv.c ##
     @@ drivers/block/zram/zram_drv.c: static int zram_rw_page(struct block_device *bdev, sector_t sector,
    @@ drivers/block/zram/zram_drv.c: static void zram_reset_device(struct zram *zram)
      	set_capacity_and_notify(zram->disk, 0);
      	part_stat_set_all(zram->disk->part0, 0);
      
    + 	up_write(&zram->init_lock);
      	/* I/O operation under all of CPU are done so let's free */
     -	zram_meta_free(zram, disksize);
     +	zram_meta_free(zram, zram->disksize);
    @@ drivers/block/zram/zram_drv.c: static void zram_reset_device(struct zram *zram)
     +	zcomp_destroy(zram->comp);
     +	zram->comp = NULL;
      	reset_bdev(zram);
    + }
      
    - 	up_write(&zram->init_lock);
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |