From: Christoph Hellwig <hch@infradead.org>
To: Anton Altaparmakov <anton@tuxera.com>
Cc: Christoph Hellwig <hch@infradead.org>, NeilBrown <neilb@suse.com>,
Jens Axboe <axboe@fb.com>, Theodore Ts'o <tytso@mit.edu>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Sougata Santra <sougata@tuxera.com>
Subject: Re: Device removal crash problems
Date: Wed, 15 Jun 2016 06:07:47 -0700 [thread overview]
Message-ID: <20160615130747.GA5914@infradead.org> (raw)
In-Reply-To: <1D4D1B85-F772-4795-A938-852F46969499@tuxera.com>
On Mon, Jun 13, 2016 at 01:26:24AM +0000, Anton Altaparmakov wrote:
> Hi Christoph,
>
> I think the reason the storage unplug crashes came back in 4.1 kernel after your work in 4.0 kernel to fix them is this commit: 6cd18e711dd8 "block: destroy bdi before blockdev is unregistered."
>
> The fix was to basically violate the lifetime rules/reference counting you put in place and destroy the bdi before the reference count reaches zero which means we are back at square one! The whole point of the reference count was specifically so that devices are not destroyed before the reference count becomes zero. Or at least that was my understanding/assumption...
Yes, that area is a mess. Unfortunately I've been too busy to fight
in in detail - since then the writeback code also got trainwrecked by
the cgroups writeback support and it will take a long time for me to
get back into it.
next prev parent reply other threads:[~2016-06-15 13:07 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-13 1:26 Device removal crash problems Anton Altaparmakov
2016-06-15 13:07 ` Christoph Hellwig [this message]
2016-07-08 1:03 ` NeilBrown
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