Re: [PATCH block/for-linus] block: blkg_destroy_all() should clear q->root_blkg and ->root_rl.blkg

[Tejun Heo]

On Sat, Sep 05, 2015 at 03:47:36PM -0400, Tejun Heo wrote:
> While making the root blkg unconditional, ec13b1d6f0a0 ("blkcg: always
> create the blkcg_gq for the root blkcg") removed the part which clears
> q->root_blkg and ->root_rl.blkg during q exit.  This leaves the two
> pointers dangling after blkg_destroy_all().  blk-throttle exit path
> performs blkg traversals and dereferences ->root_blkg and can lead to
> the following oops.

Jens, can you please route this one w/ Richard's tested-by added?

Thanks!

-- 
tejun
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