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From: NeilBrown <neilb@suse.com>
To: Francesco Dolcini <francesco@dolcini.it>
Cc: Francesco Dolcini <francesco@dolcini.it>,
	axboe@kernel.dk, tj@kernel.org, hch@lst.de, axboe@fb.com,
	akpm@linux-foundation.org, linux-block@vger.kernel.org
Subject: Re: blockdev kernel regression (bugzilla 173031)
Date: Fri, 07 Oct 2016 13:09:11 +1100	[thread overview]
Message-ID: <8760p452rc.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20161006075409.GA4059@dev1>

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On Thu, Oct 06 2016, Francesco Dolcini wrote:

> On Thu, Oct 06, 2016 at 04:42:52PM +1100, NeilBrown wrote:
> cc
>> Maybe there is a race, but that seems unlikely.
>
> Consider that just hot removal while writing is not enough to 
> reproduce systematically the bug.
>
> while true; do [ ! -f /media/usb/.not_mounted ] \
> 	&& dd if=/dev/zero of=/media/usb/aaa bs=1k \
> 	count=1 2>/dev/null && echo -n '*' ; done
>
> with lazy umount by mdev on USB flash drive removal
>
> reproduce the problem pretty always
>
>> The vfat issue is different, and is only a warning.
> Why you say is only a warning? Here the Oops with vfat on ARM/i.MX6:

I looked at:

x86 Oops information (with vfat):

in the bugzilla and didn't realized there was another one further down.
That first vfat on is just a warning.
>
>> > Regression is on commit 6cd18e7 ("block: destroy bdi before blockdev is unregistered.")
>> >
>> > Commit: bdfe0cbd746a ("Revert "ext4: remove block_device_ejected") is already present on 4.1 stable I am currently working on (2a6f417 on 4.1 branch)
>> >
>> > I wonder if commit b02176f ("block: don't release bdi while request_queue has live references") is the correct fix for this also in kernel 4.1.
>> 
>> Maybe.  It is worth a try.
>> 
>> Below is a a backport to 4.1.33.  It compiles, but I haven't tested.
>> If it works for you, I can recommend it for -stable.
>
> I confirm that it works!

Thanks.

NeilBrown

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      reply	other threads:[~2016-10-07  2:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20161004150350.GA27176@dev1>
     [not found] ` <8760p75zc6.fsf@notabene.neil.brown.name>
2016-10-05 11:18   ` blockdev kernel regression (bugzilla 173031) Francesco Dolcini
2016-10-06  5:42     ` NeilBrown
2016-10-06  7:54       ` Francesco Dolcini
2016-10-07  2:09         ` NeilBrown [this message]

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