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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Theodore Ts'o <tytso@mit.edu>
Cc: John Hubbard <jhubbard@nvidia.com>,
	Lee Jones <lee.jones@linaro.org>,
	linux-ext4@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	Dave Chinner <dchinner@redhat.com>,
	Goldwyn Rodrigues <rgoldwyn@suse.com>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Bob Peterson <rpeterso@redhat.com>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Andreas Gruenbacher <agruenba@redhat.com>,
	Ritesh Harjani <riteshh@linux.ibm.com>,
	Johannes Thumshirn <jth@kernel.org>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	cluster-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [REPORT] kernel BUG at fs/ext4/inode.c:2620 - page_buffers()
Date: Fri, 18 Feb 2022 08:51:54 +0100	[thread overview]
Message-ID: <Yg9QGm2Rygrv+lMj@kroah.com> (raw)
In-Reply-To: <Yg8bxiz02WBGf6qO@mit.edu>

On Thu, Feb 17, 2022 at 11:08:38PM -0500, Theodore Ts'o wrote:
> On Thu, Feb 17, 2022 at 05:06:45PM -0800, John Hubbard wrote:
> > Yes. And looking at the pair of backtraces below, this looks very much
> > like another aspect of the "get_user_pages problem" [1], originally
> > described in Jan Kara's 2018 email [2].
> 
> Hmm... I just posted my analysis, which tracks with yours; but I had
> forgotten about Jan's 2018 e-mail on the matter.
> 
> > I'm getting close to posting an RFC for the direct IO conversion to
> > FOLL_PIN, but even after that, various parts of the kernel (reclaim,
> > filesystems/block layer) still need to be changed so as to use
> > page_maybe_dma_pinned() to help avoid this problem. There's a bit
> > more than that, actually.
> 
> The challenge is that fixing this "the right away" is probably not
> something we can backport into an LTS kernel, whether it's 5.15 or
> 5.10... or 4.19.

Don't worry about stable backports to start with.  Do it the "right way"
first and then we can consider if it needs to be backported or not.

thanks,

greg k-h

  parent reply	other threads:[~2022-02-18  7:52 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-16 16:31 [REPORT] kernel BUG at fs/ext4/inode.c:2620 - page_buffers() Lee Jones
2022-02-18  1:06 ` John Hubbard
2022-02-18  4:08   ` Theodore Ts'o
2022-02-18  6:33     ` John Hubbard
2022-02-23 23:31       ` Theodore Ts'o
2022-02-24  0:44         ` John Hubbard
2022-02-24  4:04           ` Theodore Ts'o
2022-02-18  7:51     ` Greg Kroah-Hartman [this message]
2022-02-23 23:35       ` Theodore Ts'o
2022-02-24  1:48         ` Dave Chinner
2022-02-24  3:50           ` Theodore Ts'o
2022-02-24 10:29             ` Dave Chinner
2022-02-18  2:54 ` Theodore Ts'o
2022-02-18  4:24   ` Matthew Wilcox
2022-02-18  6:03     ` Theodore Ts'o
2022-02-25 19:24 ` [PATCH -v2] ext4: don't BUG if kernel subsystems dirty pages without asking ext4 first Theodore Ts'o
2022-02-25 20:51   ` Eric Biggers
2022-02-25 21:08     ` Theodore Ts'o
2022-02-25 21:23       ` [PATCH -v3] " Theodore Ts'o
2022-02-25 21:33         ` John Hubbard
2022-02-25 23:21           ` Theodore Ts'o
2022-02-26  0:41             ` John Hubbard
2022-02-26  1:40               ` Theodore Ts'o
2022-02-26  2:00                 ` Theodore Ts'o
2022-02-26  2:55                 ` John Hubbard
2022-03-03  4:26         ` [PATCH -v4] " Theodore Ts'o
2022-03-03  8:21           ` Christoph Hellwig
2022-03-03  9:21           ` Lee Jones
2022-03-03 14:38           ` [PATCH -v5] ext4: don't BUG if someone " Theodore Ts'o

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