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From: Matthew Wilcox <willy@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm <linux-nvdimm@lists.01.org>, Jan Kara <jack@suse.cz>,
	stable <stable@vger.kernel.org>,
	Robert Barror <robert.barror@intel.com>,
	Seema Pandit <seema.pandit@intel.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] filesystem-dax: Disable PMD support
Date: Fri, 28 Jun 2019 09:54:17 -0700	[thread overview]
Message-ID: <20190628165417.GD4286@bombadil.infradead.org> (raw)
In-Reply-To: <CAPcyv4jeRwhYWnGw9RrfDA54RRa9LK4JPuF3zQ-av=HdRqCTJw@mail.gmail.com>

On Fri, Jun 28, 2019 at 09:39:01AM -0700, Dan Williams wrote:
> On Fri, Jun 28, 2019 at 9:37 AM Matthew Wilcox <willy@infradead.org> wrote:
> > That was the conclusion I came to; that one thread holding the mmap sem
> > for read isn't being woken up when it should be.  Just need to find it ...
> > obviously it's something to do with the PMD entries.
> 
> Can you explain to me one more time, yes I'm slow on the uptake on
> this, the difference between xas_load() and xas_find_conflict() and
> why it's ok for dax_lock_page() to use xas_load() while
> grab_mapping_entry() uses xas_find_conflict()?

When used with a non-zero 'order', xas_find_conflict() will return
an entry whereas xas_load() might return a pointer to a node.
dax_lock_page() always uses a zero order, so they would always do the
same thing (xas_find_conflict() would be less efficient).

  reply	other threads:[~2019-06-28 16:54 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-27  0:15 [PATCH] filesystem-dax: Disable PMD support Dan Williams
2019-06-27 12:34 ` Matthew Wilcox
2019-06-27 16:06   ` Dan Williams
2019-06-27 18:29     ` Dan Williams
2019-06-27 18:58       ` Dan Williams
2019-06-27 19:09         ` Dan Williams
2019-06-27 19:59           ` Matthew Wilcox
2019-06-28  2:39             ` Dan Williams
2019-06-28 16:37               ` Matthew Wilcox
2019-06-28 16:39                 ` Dan Williams
2019-06-28 16:54                   ` Matthew Wilcox [this message]
2019-06-29 16:03               ` Matthew Wilcox
2019-06-30  7:27                 ` Dan Williams
2019-06-30  8:01                   ` Dan Williams
2019-06-30 15:23                     ` Matthew Wilcox
2019-06-30 21:37                       ` Dan Williams
2019-07-02  3:34                         ` Matthew Wilcox
2019-07-02 15:37                           ` Dan Williams
2019-07-03  0:22                             ` Boaz Harrosh
2019-07-03  0:42                               ` Dan Williams
2019-07-03  1:39                                 ` Boaz Harrosh
2019-07-01 12:11                       ` Jan Kara
2019-07-03 15:47                         ` Matthew Wilcox
2019-07-04 16:40                           ` Jan Kara

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