From: Matthew Wilcox <willy@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: jack@suse.cz, jlayton@kernel.org, linux-cachefs@redhat.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] netfs: Fix lockdep warning from taking sb_writers whilst holding mmap_lock
Date: Tue, 7 Dec 2021 13:13:50 +0000 [thread overview]
Message-ID: <Ya9eDiFCE2fO7K/S@casper.infradead.org> (raw)
In-Reply-To: <163887597541.1596626.2668163316598972956.stgit@warthog.procyon.org.uk>
On Tue, Dec 07, 2021 at 11:19:35AM +0000, David Howells wrote:
> Taking sb_writers whilst holding mmap_lock isn't allowed and will result in
> a lockdep warning like that below. The problem comes from cachefiles
> needing to take the sb_writers lock in order to do a write to the cache,
> but being asked to do this by netfslib called from readpage, readahead or
> write_begin[1].
Isn't it taking sb_writers _on a different filesystem_? So there's not
a real deadlock here, just a need to tell lockdep that this is a
different subclass of lock?
next prev parent reply other threads:[~2021-12-07 13:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 11:19 David Howells
2021-12-07 13:13 ` Matthew Wilcox [this message]
2021-12-07 13:32 ` David Howells
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