From: Michal Hocko <mhocko@kernel.org>
To: David Sterba <dsterba@suse.cz>
Cc: Olof Johansson <olof@lixom.net>,
dsterba@suse.de, linux-btrfs@vger.kernel.org, clm@fb.com,
linux-kernel@vger.kernel.org
Subject: Re: Circular lock dep in btrfs triggered by shrinker
Date: Tue, 23 Oct 2018 09:53:30 +0200 [thread overview]
Message-ID: <20181023075330.GP18839@dhcp22.suse.cz> (raw)
In-Reply-To: <20181022182243.GM16290@twin.jikos.cz>
On Mon 22-10-18 20:22:43, David Sterba wrote:
> On Mon, Oct 22, 2018 at 03:07:26AM -0700, Olof Johansson wrote:
> > I hit the below circular locking dependency. Seems like the assumption made in
> > 712e36c5f2a7fa56 ("btrfs: use GFP_KERNEL in btrfs_alloc_inode") either isn't
> > true, or has since changed?
>
> I think it must have been there from the beginning. There were reports
> of this lockdep warning like the below and IIRC a few more
> (https://lkml.kernel.org/r/20180627120523.GA2287@suse.cz), but without a
> resolution.
>
> Incidentally, there was a fix that's now in the 4.20 pull and only after
> I had seen your report I realized that it was the fix for the warning:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git/commit/?h=for-4.20-part1&id=84de76a2fb217dc1b6bc2965cc397d1648aa1404
>
> It disables the filesystem allocations using the memalloc_nofs mechanism
> around free space inode allocation, while my original patch expected
> only regular inodes created by VFS.
Wouldn't it be better/possible to take the mark the scope at the higher
level where you take the trans handle?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-10-23 7:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-22 10:07 Circular lock dep in btrfs triggered by shrinker Olof Johansson
2018-10-22 18:22 ` David Sterba
2018-10-23 7:53 ` Michal Hocko [this message]
2018-10-23 8:41 ` Olof Johansson
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