Re: [PATCH 0/2] block: fixes for always associate blkg
From: Jens Axboe
Date: Sat Oct 20 2018 - 17:40:34 EST
On 10/20/18 12:56 PM, Dennis Zhou wrote:
> Hi everyone,
> It was reported in  that blk_get_rl() cleanup patch was causing a
> null pointer dereference. After some back and forth debugging with
> Valdis, it turns out I wasn't properly handling association with
> recursive calls to make_request().
> Another issue was identified with the blk_get_rl() update as it is
> possible under certain circumstances that a blkg cannot be allocated
> when called in blk_get_rl(). This could result in the blkcg_root being
> returned. However, the blkcg_root is a special case where all blkgs
> share the request_queue's request_list.
> The original series can be found at .
>  https://lore.kernel.org/lkml/13987.1539646128@xxxxxxxxxxxxxxxxxxxxxxx/
>  https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@xxxxxxxxx/
> This patchset contains the following 2 patches:
> 0001 addresses an edge case where a blkg cannot be created and can
> possibly return a blkg associated with the blkcg_root. 0002 fixes the
> stale association when make_request() is called recursively.
Thanks Dennis, applied.