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Date:   Tue, 19 Jun 2018 02:22:30 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Ross Zwisler <ross.zwisler@linux.intel.com>, linux-mm@kvack.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jan Kara <jack@suse.cz>, Jeff Layton <jlayton@redhat.com>,
        Lukas Czerner <lczerner@redhat.com>,
        Christoph Hellwig <hch@lst.de>,
        Goldwyn Rodrigues <rgoldwyn@suse.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>,
        linux-nilfs@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
        Chao Yu <yuchao0@huawei.com>,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [PATCH v14 00/74] Convert page cache to XArray
Message-ID: <20180619092230.GA1438@bombadil.infradead.org>
References: <20180617020052.4759-1-willy@infradead.org>
 <20180619031257.GA12527@linux.intel.com>
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On Mon, Jun 18, 2018 at 09:12:57PM -0600, Ross Zwisler wrote:
> Hit another deadlock.  This one reproduces 100% of the time in my setup with
> XFS + DAX + generic/340.  It doesn't reproduce for me at all with
> next-20180615.  Here's the output from "echo w > /proc/sysrq-trigger":

*sigh*.  I wonder what the differences are between our setups ...

> [   92.849119] sysrq: SysRq : Show Blocked State
> [   92.850506]   task                        PC stack   pid father
> [   92.852299] holetest        D    0  1651   1466 0x00000000
> [   92.853912] Call Trace:
> [   92.854610]  __schedule+0x2c5/0xad0
> [   92.855612]  schedule+0x36/0x90
> [   92.856602]  get_unlocked_entry+0xce/0x120
> [   92.857756]  ? dax_insert_entry+0x2b0/0x2b0
> [   92.858931]  grab_mapping_entry+0x19e/0x250
> [   92.860119]  dax_iomap_pte_fault+0x115/0x1140
> [   92.860836]  dax_iomap_fault+0x37/0x40
...
> This looks very similar to the one I reported last week with generic/269.

Yeah, another missing wakeup, no doubt.  Can you bisect this?  That was
how I found the last one; bisected it to a single patch and stared very
hard at the patch until I saw it.  I'm not going to be in a position to
tinker with my DAX setup until the first week of July.