From: Jens Axboe <axboe@kernel.dk>
To: Sam Bradshaw <sbradshaw@micron.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] blkmq: Fix NULL pointer deref when all reserved tags in use
Date: Wed, 18 Mar 2015 17:07:11 -0600 [thread overview]
Message-ID: <550A051F.3000106@kernel.dk> (raw)
In-Reply-To: <550A052F.6020601@micron.com>
On 03/18/2015 05:07 PM, Sam Bradshaw wrote:
> When allocating from the reserved tags pool, bt_get() is called with
> a NULL hctx. If all tags are in use, the hw queue is kicked to push
> out any pending IO, potentially freeing tags, and tag allocation is
> retried. The problem is that blk_mq_run_hw_queue() doesn't check for
> a NULL hctx. So we avoid it with a simple NULL hctx test.
>
> This issue was introduced by:
> b32232073e80: blk-mq: fix hang in bt_get()
>
> Tested by hammering mtip32xx with concurrent smartctl/hdparm.
>
> Signed-off-by: Sam Bradshaw <sbradshaw@micron.com>
> Signed-off-by: Selvan Mani <smani@micron.com>
Thanks Sam, added to the current series.
--
Jens Axboe
prev parent reply other threads:[~2015-03-18 23:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-18 23:07 [PATCH v2] blkmq: Fix NULL pointer deref when all reserved tags in use Sam Bradshaw
2015-03-18 23:07 ` Jens Axboe [this message]
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