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From: Jens Axboe <>
To: Dennis Zhou <>
Cc: Tejun Heo <>,
	Valdis Kletnieks <>,,,
Subject: Re: [PATCH 0/2] block: fixes for always associate blkg
Date: Sat, 20 Oct 2018 15:40:22 -0600
Message-ID: <> (raw)
In-Reply-To: <>

On 10/20/18 12:56 PM, Dennis Zhou wrote:
> Hi everyone,
> It was reported in [1] 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 [2].
> [1]
> [2]
> This patchset contains the following 2 patches:
>   0001-blkcg-fix-edge-case-for-blk_get_rl-under-memory-pres.patch
>   0002-blkcg-reassociate-bios-when-make_request-is-called-r.patch
> 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.

Jens Axboe

      parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-20 18:56 Dennis Zhou
2018-10-20 18:56 ` [PATCH 1/2] blkcg: fix edge case for blk_get_rl() under memory pressure Dennis Zhou
2018-10-20 18:56 ` [PATCH 2/2] blkcg: reassociate bios when make_request() is called recursively Dennis Zhou
2018-10-20 21:40 ` Jens Axboe [this message]

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