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

From Jens Axboe <axboe@kernel.dk>
Newsgroups linux.kernel
Subject Re: [PATCH block/for-linus] block: blkg_destroy_all() should clear q->root_blkg and ->root_rl.blkg
Date 2015-09-08 17:40 +0200
Message-ID <q6ta2-8oh-25@gated-at.bofh.it> (permalink)
References (6 earlier) <q5nJo-4zK-5@gated-at.bofh.it> <q5nT4-4L2-19@gated-at.bofh.it> <q5qxz-6Y-7@gated-at.bofh.it> <q5rDk-1Dm-7@gated-at.bofh.it> <q6ta3-8oh-27@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On 09/08/2015 09:31 AM, Tejun Heo wrote:
> 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?

Yup, added, thanks.

-- 
Jens Axboe

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Re: [PATCH block/for-linus] block: blkg_destroy_all() should clear  q->root_blkg and ->root_rl.blkg Jens Axboe <axboe@kernel.dk> - 2015-09-08 17:40 +0200

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