From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
"jianchao.wang" <jianchao.w.wang@oracle.com>,
Guenter Roeck <linux@roeck-us.net>,
stable@vger.kernel.org
Subject: Re: [PATCH 4.21 V3] blk-mq: not embed .mq_kobj and ctx->kobj into queue instance
Date: Tue, 20 Nov 2018 08:51:50 +0100 [thread overview]
Message-ID: <20181120075150.GF15276@kroah.com> (raw)
In-Reply-To: <20181120014435.3339-1-ming.lei@redhat.com>
On Tue, Nov 20, 2018 at 09:44:35AM +0800, Ming Lei wrote:
> Even though .mq_kobj, ctx->kobj and q->kobj share same lifetime
> from block layer's view, actually they don't because userspace may
> grab one kobject anytime via sysfs.
>
> This patch fixes the issue by the following approach:
>
> 1) introduce 'struct blk_mq_ctxs' for holding .mq_kobj and managing
> all ctxs
>
> 2) free all allocated ctxs and the 'blk_mq_ctxs' instance in release
> handler of .mq_kobj
>
> 3) grab one ref of .mq_kobj before initializing each ctx->kobj, so that
> .mq_kobj is always released after all ctxs are freed.
>
> This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE
> is enabled.
>
> Reported-by: Guenter Roeck <linux@roeck-us.net>
> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: stable@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> V3:
> - keep to allocate q->queue_ctx via percpu allocator, so one extra
> pointer reference can be saved for getting ctx
> V2:
> - allocate 'blk_mq_ctx' inside blk_mq_init_allocated_queue()
> - allocate q->mq_kobj directly
Not tested, but seems sane from a kobject point-of-view:
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
next prev parent reply other threads:[~2018-11-20 18:19 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-20 1:44 [PATCH 4.21 V3] blk-mq: not embed .mq_kobj and ctx->kobj into queue instance Ming Lei
2018-11-20 7:51 ` Greg Kroah-Hartman [this message]
2018-11-20 16:45 ` Guenter Roeck
2018-11-20 17:35 ` Jens Axboe
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