From: Jan Kara <jack@suse.cz>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: Paolo Valente <paolo.valente@linaro.org>,
Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
Chris Murphy <lists@colorremedies.com>,
linux-block <linux-block@vger.kernel.org>
Subject: Re: 5.17, WARNING: at block/bfq-iosched.c:602 bfqq_request_over_limit+0x122/0x3a0
Date: Thu, 7 Apr 2022 16:16:16 +0200 [thread overview]
Message-ID: <20220407141616.koxfr7vhhi4brqyg@quack3.lan> (raw)
In-Reply-To: <20220406160359.5stdu2unbu2kiva5@quack3.lan>
On Wed 06-04-22 18:03:59, Jan Kara wrote:
> Hello!
>
> On Wed 06-04-22 09:44:55, yukuai (C) wrote:
> > 在 2022/04/04 22:35, Paolo Valente 写道:
> > > This seems to have to do with Jan's patches on tag allocation. I'm CCing him too. Jan, I'm willing to provide my usual dev version for testing, if useful.
> >
> > I had observed this warning for a long time, and it's very to reporduce
> > by our reporducer for the problem that Jan fixed recently.
> >
> > I thougt this warning is due to bfqq is associated with wrong cgroup,
> > which should be fixed by Jan's patch.
> >
> > What do you think, Jan ?
>
> Hum, the warning suggests that the blkcg's idea of cgroup hierarchy is not in
> sync with BFQ's idea of cgroup hierarchy. One possibility how this could
> happen is if bfqq is moved from one bfqg to another between the depth check
> and the for_each_entity() loop. This should actually get fixed as a
> side-effect of my patches because they change the logic so that alive bfqq
> can change parent only if they contain a single process. But nevertheless
> we should make the logic inside bfqq_request_over_limit() more robust in
> place of process moving between cgroups. So I'll send a patch for that on
> top of my patches.
Posted: https://lore.kernel.org/all/20220407140738.9723-1-jack@suse.cz
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2022-04-07 14:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-02 6:39 5.17, WARNING: at block/bfq-iosched.c:602 bfqq_request_over_limit+0x122/0x3a0 Chris Murphy
2022-04-02 17:47 ` Jens Axboe
2022-04-04 14:35 ` Paolo Valente
2022-04-06 1:44 ` yukuai (C)
2022-04-06 16:03 ` Jan Kara
2022-04-07 14:16 ` Jan Kara [this message]
2022-04-04 8:35 ` Thorsten Leemhuis
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