From: Dan Williams <dan.j.williams@intel.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Linux MM <linux-mm@kvack.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"Barror, Robert" <robert.barror@intel.com>
Subject: Re: Hang / zombie process from Xarray page-fault conversion (bisected)
Date: Mon, 11 Mar 2019 20:35:05 -0700 [thread overview]
Message-ID: <CAPcyv4jG5r2LOesxSx+Mdf+L_gQWqnhk+gKZyKAAPTHy1Drvqw@mail.gmail.com> (raw)
In-Reply-To: <20190311150947.GD19508@bombadil.infradead.org>
On Mon, Mar 11, 2019 at 8:10 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Mar 07, 2019 at 10:16:17PM -0800, Dan Williams wrote:
> > Hi Willy,
> >
> > We're seeing a case where RocksDB hangs and becomes defunct when
> > trying to kill the process. v4.19 succeeds and v4.20 fails. Robert was
> > able to bisect this to commit b15cd800682f "dax: Convert page fault
> > handlers to XArray".
> >
> > I see some direct usage of xa_index and wonder if there are some more
> > pmd fixups to do?
> >
> > Other thoughts?
>
> I don't see why killing a process would have much to do with PMD
> misalignment. The symptoms (hanging on a signal) smell much more like
> leaving a locked entry in the tree. Is this easy to reproduce? Can you
> get /proc/$pid/stack for a hung task?
It's fairly easy to reproduce, I'll see if I can package up all the
dependencies into something that fails in a VM.
It's limited to xfs, no failure on ext4 to date.
The hung process appears to be:
kworker/53:1-xfs-sync/pmem0
...and then the rest of the database processes grind to a halt from there.
Robert was kind enough to capture /proc/$pid/stack, but nothing interesting:
[<0>] worker_thread+0xb2/0x380
[<0>] kthread+0x112/0x130
[<0>] ret_from_fork+0x1f/0x40
[<0>] 0xffffffffffffffff
next prev parent reply other threads:[~2019-03-12 3:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-08 6:16 Hang / zombie process from Xarray page-fault conversion (bisected) Dan Williams
2019-03-11 15:09 ` Matthew Wilcox
2019-03-12 3:35 ` Dan Williams [this message]
2019-03-12 4:37 ` Dave Chinner
2019-03-12 16:53 ` Barror, Robert
2019-03-14 7:34 ` Dan Williams
2019-03-15 2:26 ` Dave Chinner
2019-03-15 2:46 ` Dan Williams
2019-05-04 19:42 ` Matthew Wilcox
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