Re: [PATCH 1/2] blk-mq: not embed .mq_kobj and ctx->kobj into queue instance

Sasha Levin
2018-11-16T16:07:08Z

On Fri, Nov 16, 2018 at 03:49:06PM +0800, Ming Lei wrote:
>On Fri, Nov 16, 2018 at 01:52:05AM -0500, Sasha Levin wrote:
>> On Fri, Nov 16, 2018 at 11:28:25AM +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, so each kobject's lifetime has
>> > to be independent, then the objects(mq_kobj, ctx) which hosts its
>> > own kobject have to be allocated dynamically.
>> >
>> > This patch fixes kernel panic issue during booting when DEBUG_KOBJECT_RELEASE
>> > is enabled.
>> >
>> > Reported-by: Guenter Roeck <linux@roeck-us.net>
>> > 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>
>>
>> What does this patch depend on? It doesn't apply to Linus's tree nor to
>> the block tree.
>>
>> Also, could you please cc lkml with patches?
>
>It depends on for-4.21/block.

And in particular on commit 392546aed22 ("blk-mq: separate number of
hardware queues from nr_cpu_ids") which isn't tagged for stable nor
looks like stable material, so this proposed patch doesn't backport
cleanly to any of the stable trees.

--
Thanks,
Sasha