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From: Andreas Gruenbacher <agruenba@redhat.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Andreas Grünbacher" <andreas.gruenbacher@gmail.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	"Junxiao Bi" <junxiao.bi@oracle.com>,
	"William Kucharski" <william.kucharski@oracle.com>,
	"Joseph Qi" <joseph.qi@linux.alibaba.com>,
	"John Hubbard" <jhubbard@nvidia.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-f2fs-devel@lists.sourceforge.net,
	cluster-devel <cluster-devel@redhat.com>,
	Linux-MM <linux-mm@kvack.org>,
	ocfs2-devel@oss.oracle.com,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	linux-erofs@lists.ozlabs.org, "Christoph Hellwig" <hch@lst.de>,
	linux-btrfs@vger.kernel.org,
	"Steven Whitehouse" <swhiteho@redhat.com>,
	"Bob Peterson" <rpeterso@redhat.com>
Subject: Re: [Cluster-devel] [PATCH v11 16/25] fs: Convert mpage_readpages to mpage_readahead
Date: Thu, 18 Jun 2020 14:46:03 +0200
Message-ID: <CAHc6FU7NLRHKRJJ6c2kQT0ig8ed1n+3qR-YcSCWzXOeJCUsLbA@mail.gmail.com> (raw)
In-Reply-To: <20200617022157.GF8681@bombadil.infradead.org>

On Wed, Jun 17, 2020 at 4:22 AM Matthew Wilcox <willy@infradead.org> wrote:
> On Wed, Jun 17, 2020 at 02:57:14AM +0200, Andreas Grünbacher wrote:
> > Am Mi., 17. Juni 2020 um 02:33 Uhr schrieb Matthew Wilcox <willy@infradead.org>:
> > >
> > > On Wed, Jun 17, 2020 at 12:36:13AM +0200, Andreas Gruenbacher wrote:
> > > > Am Mi., 15. Apr. 2020 um 23:39 Uhr schrieb Matthew Wilcox <willy@infradead.org>:
> > > > > From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> > > > >
> > > > > Implement the new readahead aop and convert all callers (block_dev,
> > > > > exfat, ext2, fat, gfs2, hpfs, isofs, jfs, nilfs2, ocfs2, omfs, qnx6,
> > > > > reiserfs & udf).  The callers are all trivial except for GFS2 & OCFS2.
> > > >
> > > > This patch leads to an ABBA deadlock in xfstest generic/095 on gfs2.
> > > >
> > > > Our lock hierarchy is such that the inode cluster lock ("inode glock")
> > > > for an inode needs to be taken before any page locks in that inode's
> > > > address space.
> > >
> > > How does that work for ...
> > >
> > > writepage:              yes, unlocks (see below)
> > > readpage:               yes, unlocks
> > > invalidatepage:         yes
> > > releasepage:            yes
> > > freepage:               yes
> > > isolate_page:           yes
> > > migratepage:            yes (both)
> > > putback_page:           yes
> > > launder_page:           yes
> > > is_partially_uptodate:  yes
> > > error_remove_page:      yes
> > >
> > > Is there a reason that you don't take the glock in the higher level
> > > ops which are called before readhead gets called?  I'm looking at XFS,
> > > and it takes the xfs_ilock SHARED in xfs_file_buffered_aio_read()
> > > (called from xfs_file_read_iter).
> >
> > Right, the approach from the following thread might fix this:
> >
> > https://lore.kernel.org/linux-fsdevel/20191122235324.17245-1-agruenba@redhat.com/T/#t
>
> In general, I think this is a sound approach.
>
> Specifically, I think FAULT_FLAG_CACHED can go away.  map_pages()
> will bring in the pages which are in the page cache, so when we get to
> gfs2_fault(), we know there's a reason to acquire the glock.

We'd still be grabbing a glock while holding a dependent page lock.
Another process could be holding the glock and could try to grab the
same page lock (i.e., a concurrent writer), leading to the same kind
of deadlock.

Andreas


  reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-14 15:02 [PATCH v11 00/25] Change readahead API Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 01/25] mm: Move readahead prototypes from mm.h Matthew Wilcox
2020-04-15  9:10   ` Johannes Thumshirn
2020-04-14 15:02 ` [PATCH v11 02/25] mm: Return void from various readahead functions Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 03/25] mm: Ignore return value of ->readpages Matthew Wilcox
2020-04-15  9:17   ` Johannes Thumshirn
2020-04-14 15:02 ` [PATCH v11 04/25] mm: Move readahead nr_pages check into read_pages Matthew Wilcox
2020-04-15  9:19   ` Johannes Thumshirn
2020-04-14 15:02 ` [PATCH v11 05/25] mm: Add new readahead_control API Matthew Wilcox
2020-04-15  1:17   ` Andrew Morton
2020-04-15  2:18     ` Matthew Wilcox
2020-04-15  4:56       ` Andrew Morton
2020-04-15 11:22         ` Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 06/25] mm: Use readahead_control to pass arguments Matthew Wilcox
2020-04-15  9:30   ` Johannes Thumshirn
2020-04-14 15:02 ` [PATCH v11 07/25] mm: Rename various 'offset' parameters to 'index' Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 08/25] mm: rename readahead loop variable to 'i' Matthew Wilcox
2020-04-15  9:31   ` Johannes Thumshirn
2020-04-14 15:02 ` [PATCH v11 09/25] mm: Remove 'page_offset' from readahead loop Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 10/25] mm: Put readahead pages in cache earlier Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 11/25] mm: Add readahead address space operation Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 12/25] mm: Move end_index check out of readahead loop Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 13/25] mm: Add page_cache_readahead_unbounded Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 14/25] mm: Document why we don't set PageReadahead Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 15/25] mm: Use memalloc_nofs_save in readahead path Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 16/25] fs: Convert mpage_readpages to mpage_readahead Matthew Wilcox
2020-06-16 22:36   ` [Cluster-devel] " Andreas Gruenbacher
2020-06-17  0:32     ` Matthew Wilcox
2020-06-17  0:57       ` Andreas Grünbacher
2020-06-17  2:21         ` Matthew Wilcox
2020-06-18 12:46           ` Andreas Gruenbacher [this message]
2020-06-18 15:03             ` Matthew Wilcox
2020-06-18 16:40               ` Andreas Gruenbacher
2020-04-14 15:02 ` [PATCH v11 17/25] btrfs: Convert from readpages to readahead Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 18/25] erofs: Convert uncompressed files " Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 19/25] erofs: Convert compressed " Matthew Wilcox
2020-04-21  5:42   ` Andrew Morton
2020-04-21  7:28     ` Gao Xiang
2020-04-14 15:02 ` [PATCH v11 20/25] ext4: Convert " Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 21/25] ext4: Pass the inode to ext4_mpage_readpages Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 22/25] f2fs: Convert from readpages to readahead Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 23/25] f2fs: Pass the inode to f2fs_mpage_readpages Matthew Wilcox
2020-04-14 15:02 ` [PATCH v11 24/25] fuse: Convert from readpages to readahead Matthew Wilcox
2020-04-20 11:14   ` Miklos Szeredi
2020-04-20 11:43     ` Matthew Wilcox
2020-04-20 11:54       ` Miklos Szeredi
2020-04-14 15:02 ` [PATCH v11 25/25] iomap: " Matthew Wilcox

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