From: Damien Le Moal <dlemoal@kernel.org>
To: Nilay Shroff <nilay@linux.ibm.com>, linux-block@vger.kernel.org
Cc: hch@lst.de, ming.lei@redhat.com, hare@suse.de, axboe@kernel.dk,
johannes.thumshirn@wdc.com, gjoyce@ibm.com
Subject: Re: [PATCH 1/2] lib/sbitmap: fix kernel crash observed when sbitmap depth is zero
Date: Mon, 21 Jul 2025 22:02:11 +0900 [thread overview]
Message-ID: <ec79f6be-bd33-4654-b933-edb021a5e780@kernel.org> (raw)
In-Reply-To: <20250720113553.913034-2-nilay@linux.ibm.com>
On 2025/07/20 20:35, Nilay Shroff wrote:
> We observed a kernel crash when the I/O scheduler allocates an sbitmap
> for a hardware queue (hctx) that has no associated software queues (ctx),
> and later attempts to free it. When no software queues are mapped to a
> hardware queue, the sbitmap is initialized with a depth of zero. In such
> cases, the sbitmap_init_node() function should set sb->alloc_hint to NULL.
> However, if this is not done, sb->alloc_hint may contain garbage, and
> calling sbitmap_free() will pass this invalid pointer to free_percpu(),
> resulting in a kernel crash.
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
--
Damien Le Moal
Western Digital Research
next prev parent reply other threads:[~2025-07-21 13:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-20 11:35 [PATCH 0/2] fix sbitmap initialization and null_blk tagset setup Nilay Shroff
2025-07-20 11:35 ` [PATCH 1/2] lib/sbitmap: fix kernel crash observed when sbitmap depth is zero Nilay Shroff
2025-07-21 7:15 ` Hannes Reinecke
2025-07-21 13:02 ` Damien Le Moal [this message]
2025-07-20 11:35 ` [PATCH 2/2] null_blk: fix set->driver_data while setting up tagset Nilay Shroff
2025-07-21 7:16 ` Hannes Reinecke
2025-07-21 13:04 ` Damien Le Moal
2025-07-21 13:37 ` Nilay Shroff
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