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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	linux-ext4@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	linux-block@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: REGRESSION: 37f4a24c2469: blk-mq: centralise related handling into blk_mq_get_driver_tag
Date: Thu, 24 Sep 2020 21:13:11 -0400	[thread overview]
Message-ID: <20200925011311.GJ482521@mit.edu> (raw)
In-Reply-To: <20200924143345.GD482521@mit.edu>

On Thu, Sep 24, 2020 at 10:33:45AM -0400, Theodore Y. Ts'o wrote:
> HOWEVER, thanks to a hint from a colleague at $WORK, and realizing
> that one of the stack traces had virtio balloon in the trace, I
> realized that when I switched the GCE VM type from e1-standard-2 to
> n1-standard-2 (where e1 VM's are cheaper because they use
> virtio-balloon to better manage host OS memory utilization), problem
> has become, much, *much* rarer (and possibly has gone away, although
> I'm going to want to run a lot more tests before I say that
> conclusively) on my test setup.  At the very least, using an n1 VM
> (which doesn't have virtio-balloon enabled in the hypervisor) is
> enough to unblock ext4 development.

.... and I spoke too soon.  A number of runs using -rc6 are now
failing even with the n1-standard-2 VM, so virtio-ballon may not be an
indicator.

This is why debugging this is frustrating; it is very much a heisenbug
--- although 5.8 seems to work completely reliably, as does commits
before 37f4a24c2469.  Anything after that point will show random
failures.  :-(

						- Ted




  reply	other threads:[~2020-09-25  1:13 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-03 23:02 [PATCH] ext4: flag as supporting buffered async reads Jens Axboe
2020-08-11 14:31 ` Jens Axboe
2020-08-18 18:11 ` Theodore Y. Ts'o
2020-08-18 18:12   ` Jens Axboe
2020-08-21 21:26     ` Jens Axboe
2020-08-22 14:33       ` Theodore Y. Ts'o
2020-08-22 15:48         ` Jens Axboe
2020-08-24 10:56           ` Jens Axboe
2020-08-25 14:18             ` Jens Axboe
2020-08-27  1:54               ` Jens Axboe
2020-09-04  0:10                 ` Jens Axboe
2020-09-04  3:55                   ` Theodore Y. Ts'o
2020-09-04 14:51                     ` Jens Axboe
2020-09-04 15:25                       ` Darrick J. Wong
2020-09-15  4:45                     ` REGRESSION: 37f4a24c2469: blk-mq: centralise related handling into blk_mq_get_driver_tag Theodore Y. Ts'o
2020-09-15  7:33                       ` Ming Lei
2020-09-15 22:45                         ` Theodore Y. Ts'o
2020-09-15 23:09                           ` Ming Lei
2020-09-16 20:20                             ` Theodore Y. Ts'o
2020-09-17  2:20                               ` Ming Lei
2020-09-17 14:30                                 ` Theodore Y. Ts'o
2020-09-17 23:08                                   ` Ming Lei
2020-09-24  0:59                                   ` Ming Lei
2020-09-24 14:33                                     ` Theodore Y. Ts'o
2020-09-25  1:13                                       ` Theodore Y. Ts'o [this message]
2020-09-25  7:31                                         ` Ming Lei
2020-09-25 16:19                                           ` Ming Lei
2020-09-25 16:32                                             ` Shakeel Butt
2020-09-25 16:47                                               ` Shakeel Butt
2020-09-25 17:22                                                 ` Roman Gushchin
2020-09-25 17:17                                             ` Linus Torvalds
2020-09-25 17:22                                               ` Shakeel Butt
2020-09-25 17:35                                                 ` Shakeel Butt
2020-09-25 17:47                                                   ` Roman Gushchin
2020-09-25 17:58                                                     ` Shakeel Butt
2020-09-25 19:19                                                       ` Shakeel Butt
2020-09-25 20:56                                                         ` Roman Gushchin
2020-09-25 21:18                                                           ` Shakeel Butt
2020-09-27 17:38                                                             ` Theodore Y. Ts'o
2020-09-26  1:43                                                         ` Ming Lei
2020-09-26  6:42                                                           ` Roman Gushchin
2020-09-25  1:14                                       ` Ming Lei
2020-09-25  2:34                                         ` Ming Lei
2020-10-02 20:08 ` [PATCH] ext4: flag as supporting buffered async reads Theodore Y. Ts'o
2020-10-02 20:10   ` Jens Axboe

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