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From: "Michal Koutný" <mkoutny@suse.com>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: hch@infradead.org, tj@kernel.org, axboe@kernel.dk,
	cgroups@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [PATCH v4 2/2] block: cancel all throttled bios in del_gendisk()
Date: Fri, 3 Dec 2021 11:27:39 +0100	[thread overview]
Message-ID: <20211203102739.GB64349@blackbody.suse.cz> (raw)
In-Reply-To: <95825098-a532-a0e4-9ed0-0b5f2a0e5f04@huawei.com>

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On Fri, Dec 03, 2021 at 03:50:01PM +0800, "yukuai (C)" <yukuai3@huawei.com> wrote:
> blkg_destroy() is protected by the queue_lock，so I think queue_lock can
> protect such concurrent scenario.

blkg_destroy() is not as destroying :-) as actual free, you should
synchronize against (the queue_lock ensures this for
pd_free_fn=throtl_pd_free but you may still trip on blkcg after
blkcg_css_free()).

[Actually, I think you should see a warning in your situation if you
enable CONFIG_PROVE_RCU.]

HTH,
Michal

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WARNING: multiple messages have this Message-ID (diff)
From: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>
To: "yukuai (C)" <yukuai3-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
Cc: hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org,
	tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	yi.zhang-hv44wF8Li93QT0dZR+AlfA@public.gmane.org
Subject: Re: [PATCH v4 2/2] block: cancel all throttled bios in del_gendisk()
Date: Fri, 3 Dec 2021 11:27:39 +0100	[thread overview]
Message-ID: <20211203102739.GB64349@blackbody.suse.cz> (raw)
In-Reply-To: <95825098-a532-a0e4-9ed0-0b5f2a0e5f04-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

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On Fri, Dec 03, 2021 at 03:50:01PM +0800, "yukuai (C)" <yukuai3-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> wrote:
> blkg_destroy() is protected by the queue_lock，so I think queue_lock can
> protect such concurrent scenario.

blkg_destroy() is not as destroying :-) as actual free, you should
synchronize against (the queue_lock ensures this for
pd_free_fn=throtl_pd_free but you may still trip on blkcg after
blkcg_css_free()).

[Actually, I think you should see a warning in your situation if you
enable CONFIG_PROVE_RCU.]

HTH,
Michal

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  reply	other threads:[~2021-12-03 10:27 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-02 13:04 [PATCH v4 0/2] cancel all throttled bios in del_gendisk() Yu Kuai
2021-12-02 13:04 ` Yu Kuai
2021-12-02 13:04 ` [PATCH v4 1/2] blk-throtl: move WARN_ON_ONCE() from throtl_rb_first() to it's caller Yu Kuai
2021-12-02 13:04   ` Yu Kuai
2021-12-02 13:04 ` [PATCH v4 2/2] block: cancel all throttled bios in del_gendisk() Yu Kuai
2021-12-02 13:04   ` Yu Kuai
2021-12-02 14:48   ` Michal Koutný
2021-12-02 14:48     ` Michal Koutný
2021-12-03  7:50     ` yukuai (C)
2021-12-03  7:50       ` yukuai (C)
2021-12-03 10:27       ` Michal Koutný [this message]
2021-12-03 10:27         ` Michal Koutný
2021-12-04  8:03         ` yukuai (C)
2021-12-04  8:03           ` yukuai (C)
2021-12-06 15:43           ` Michal Koutný
2021-12-06 15:43             ` Michal Koutný

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