From: Christoph Hellwig <hch@infradead.org>
To: Jan Stancek <jstancek@redhat.com>
Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
hch@infradead.org, darrick.wong@oracle.com,
linuxppc-dev@lists.ozlabs.org,
Memory Management <mm-qe@redhat.com>,
LTP Mailing List <ltp@lists.linux.it>,
Linux Stable maillist <stable@vger.kernel.org>,
CKI Project <cki-project@redhat.com>,
Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [bug] userspace hitting sporadic SIGBUS on xfs (Power9, ppc64le), v4.19 and later
Date: Tue, 3 Dec 2019 05:07:57 -0800 [thread overview]
Message-ID: <20191203130757.GA2267@infradead.org> (raw)
In-Reply-To: <1766807082.14812757.1575377439007.JavaMail.zimbra@redhat.com>
On Tue, Dec 03, 2019 at 07:50:39AM -0500, Jan Stancek wrote:
> My theory is that there's a race in iomap. There appear to be
> interleaved calls to iomap_set_range_uptodate() for same page
> with varying offset and length. Each call sees bitmap as _not_
> entirely "uptodate" and hence doesn't call SetPageUptodate().
> Even though each bit in bitmap ends up uptodate by the time
> all calls finish.
Weird. That should be prevented by the page lock that all callers
of iomap_set_range_uptodate. But in case I miss something, does
the patch below trigger? If not it is not jut a race, but might
be some weird ordering problem with the bitops, especially if it
only triggers on ppc, which is very weakly ordered.
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index d33c7bc5ee92..25e942c71590 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -148,6 +148,8 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
unsigned int i;
bool uptodate = true;
+ WARN_ON_ONCE(!PageLocked(page));
+
if (iop) {
for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
if (i >= first && i <= last)
next prev parent reply other threads:[~2019-12-03 13:08 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-30 5:26 ❌ FAIL: Test report for kernel 5.3.13-3b5f971.cki (stable-queue) CKI Project
2019-11-30 21:56 ` Jan Stancek
2019-12-02 5:46 ` Michael Ellerman
2019-12-02 12:30 ` Jan Stancek
2019-12-03 12:50 ` [bug] userspace hitting sporadic SIGBUS on xfs (Power9, ppc64le), v4.19 and later Jan Stancek
2019-12-03 13:07 ` Christoph Hellwig [this message]
2019-12-03 14:35 ` Jan Stancek
2019-12-03 16:08 ` Darrick J. Wong
2019-12-03 19:09 ` Christoph Hellwig
2019-12-04 14:43 ` Jan Stancek
2019-12-07 0:02 ` dftxbs3e
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191203130757.GA2267@infradead.org \
--to=hch@infradead.org \
--cc=cki-project@redhat.com \
--cc=darrick.wong@oracle.com \
--cc=jstancek@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=ltp@lists.linux.it \
--cc=mm-qe@redhat.com \
--cc=mpe@ellerman.id.au \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).