Linux-Fsdevel Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Qian Cai <cai@lca.pw>
Cc: Matthew Wilcox <willy@infradead.org>,
	darrick.wong@oracle.com, hch@infradead.org,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, khlebnikov@yandex-team.ru
Subject: Re: WARN_ON_ONCE(1) in iomap_dio_actor()
Date: Sun, 26 Jul 2020 16:24:12 +0100	[thread overview]
Message-ID: <20200726152412.GA26614@infradead.org> (raw)
In-Reply-To: <20200724182431.GA4871@lca.pw>

On Fri, Jul 24, 2020 at 02:24:32PM -0400, Qian Cai wrote:
> On Fri, Jun 19, 2020 at 05:17:47PM -0700, Matthew Wilcox wrote:
> > On Fri, Jun 19, 2020 at 05:17:50PM -0400, Qian Cai wrote:
> > > Running a syscall fuzzer by a normal user could trigger this,
> > > 
> > > [55649.329999][T515839] WARNING: CPU: 6 PID: 515839 at fs/iomap/direct-io.c:391 iomap_dio_actor+0x29c/0x420
> > ...
> > > 371 static loff_t
> > > 372 iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
> > > 373                 void *data, struct iomap *iomap, struct iomap *srcmap)
> > > 374 {
> > > 375         struct iomap_dio *dio = data;
> > > 376
> > > 377         switch (iomap->type) {
> > > 378         case IOMAP_HOLE:
> > > 379                 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
> > > 380                         return -EIO;
> > > 381                 return iomap_dio_hole_actor(length, dio);
> > > 382         case IOMAP_UNWRITTEN:
> > > 383                 if (!(dio->flags & IOMAP_DIO_WRITE))
> > > 384                         return iomap_dio_hole_actor(length, dio);
> > > 385                 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
> > > 386         case IOMAP_MAPPED:
> > > 387                 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
> > > 388         case IOMAP_INLINE:
> > > 389                 return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
> > > 390         default:
> > > 391                 WARN_ON_ONCE(1);
> > > 392                 return -EIO;
> > > 393         }
> > > 394 }
> > > 
> > > Could that be iomap->type == IOMAP_DELALLOC ? Looking throught the logs,
> > > it contains a few pread64() calls until this happens,
> > 
> > It _shouldn't_ be able to happen.  XFS writes back ranges which exist
> > in the page cache upon seeing an O_DIRECT I/O.  So it's not supposed to
> > be possible for there to be an extent which is waiting for the contents
> > of the page cache to be written back.
> 
> Okay, it is IOMAP_DELALLOC. We have,

Can you share the fuzzer?  If we end up with delalloc space here we
probably need to fix a bug in the cache invalidation code.

  reply	other threads:[~2020-07-26 15:24 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-19 21:17 Qian Cai
2020-06-20  0:17 ` Matthew Wilcox
2020-06-21  2:04   ` Qian Cai
2020-07-24 18:24   ` Qian Cai
2020-07-26 15:24     ` Christoph Hellwig [this message]
2020-07-26 22:51       ` Qian Cai
2020-08-11  2:03       ` Qian Cai
2020-08-13  5:44         ` Dave Chinner
2020-08-13  7:52           ` Qian Cai
2020-08-17  7:07             ` Christoph Hellwig

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=20200726152412.GA26614@infradead.org \
    --to=hch@infradead.org \
    --cc=cai@lca.pw \
    --cc=darrick.wong@oracle.com \
    --cc=khlebnikov@yandex-team.ru \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=willy@infradead.org \
    --subject='Re: WARN_ON_ONCE(1) in iomap_dio_actor()' \
    /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

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).