From: Nilay Shroff <nilay@linux.ibm.com>
To: Zizhi Wo <wozizhi@huaweicloud.com>,
axboe@kernel.dk, dlemoal@kernel.org, kch@nvidia.com,
johannes.thumshirn@wdc.com, kbusch@kernel.org,
bvanassche@acm.org, linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, yangerkun@huawei.com,
chengzhihao1@huawei.com, wozizhi@huawei.com
Subject: Re: [PATCH V5 5/9] null_blk: free zones array on device power-off
Date: Wed, 15 Jul 2026 19:44:37 +0530 [thread overview]
Message-ID: <2f61dfa0-ca63-4d81-a702-7fdd4a2e0f4e@linux.ibm.com> (raw)
In-Reply-To: <20260714041805.1088702-6-wozizhi@huaweicloud.com>
On 7/14/26 9:48 AM, Zizhi Wo wrote:
> null_init_zoned_dev() allocates dev->zones when a zoned device is powered
> on, but null_del_dev() never frees it on power-off; dev->zones is only
> freed later in null_free_dev(), when the configfs directory is removed. If
> the device is powered off and then on again, null_init_zoned_dev()
> allocates a new array and overwrites the dev->zones pointer, leaking the
> previous allocation each power cycle.
>
> Free dev->zones in null_del_dev() via null_free_zoned_dev() to solve it.
> And calling null_free_zoned_dev() in null_free_dev() is no longer necessary
> because every caller already invokes null_del_dev() first: via
> nullb_group_drop_item() before nullb_device_release(), in the
> null_add_dev() error path of null_create_dev(), and in null_destroy_dev().
> Remove the redundant call.
>
> And take &lock around zone_cond_store() in the two store wrappers to
> serialize dev->zones check-and-deref against its alloc/free, which already
> run under &lock. The reason there was no problem before is that only
> nullb_device_release() or null_exit() frees the dev->zones, which
> guarantees that subsequent users won't access the configfs interface.
>
> Fixes: ca4b2a011948 ("null_blk: add zone support")
> Assisted-by: Claude-Code:GLM-5.2
> Signed-off-by: Zizhi Wo<wozizhi@huawei.com>
Looks good to me.
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
next prev parent reply other threads:[~2026-07-15 14:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-14 4:17 [PATCH V5 0/9] null_blk: fix init/exit races and memleaks Zizhi Wo
2026-07-14 4:17 ` [PATCH V5 1/9] null_blk: use DEFINE_MUTEX for the file-scope mutex Zizhi Wo
2026-07-14 4:17 ` [PATCH V5 2/9] null_blk: register configfs subsystem after creating default devices Zizhi Wo
2026-07-14 4:17 ` [PATCH V5 3/9] null_blk: move unregister_blkdev() after destroying dev in null_exit() Zizhi Wo
2026-07-14 4:18 ` [PATCH V5 4/9] null_blk: free global tag_set on init error path Zizhi Wo
2026-07-14 4:18 ` [PATCH V5 5/9] null_blk: free zones array on device power-off Zizhi Wo
2026-07-15 14:14 ` Nilay Shroff [this message]
2026-07-14 4:18 ` [PATCH V5 6/9] null_blk: clean up null_del_dev() to use cached dev pointer Zizhi Wo
2026-07-14 4:18 ` [PATCH V5 7/9] null_blk: reject per-device queue resize for shared tag set Zizhi Wo
2026-07-15 13:42 ` Nilay Shroff
2026-07-14 4:18 ` [PATCH V5 8/9] null_blk: serialize configfs attribute stores with device setup Zizhi Wo
2026-07-14 4:18 ` [PATCH V5 9/9] null_blk: serialize configfs attribute shows with the file-scope lock Zizhi Wo
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