Re: btrfs bio linked list corruption.
From: Dave Jones
Date: Thu Oct 13 2016 - 18:24:08 EST
On Thu, Oct 13, 2016 at 05:18:46PM -0400, Chris Mason wrote:
> > > > WARNING: CPU: 1 PID: 21706 at fs/btrfs/transaction.c:489 start_transaction+0x40a/0x440 [btrfs]
> > > > CPU: 1 PID: 21706 Comm: trinity-c16 Not tainted 4.8.0-think+ #14
> > > > ffffc900019076a8 ffffffffb731ff3c 0000000000000000 0000000000000000
> > > > ffffc900019076e8 ffffffffb707a6c1 000001e9f5806ce0 ffff8804f74c4d98
> > > > 0000000000000801 ffff880501cfa2a8 000000000000008a 000000000000008a
> > >
> > > This isn't even IO. Uuughhhh. We're going to need a fast enough test
> > > that we can bisect.
> > Progress...
> > I've found that this combination of syscalls..
> > ./trinity -C64 -q -l off -a64 --enable-fds=testfile -c fsync -c fsetxattr -c lremovexattr -c pwritev2
> > hits one of these two bugs in a few minutes runtime.
> > Just the xattr syscalls + fsync isn't enough, neither is just pwrite + fsync.
> > Mix them together though, and something goes awry.
> Hasn't triggered here yet. I'll leave it running though.
With that combo of params I triggered it 3-4 times in a row within minutes.. Then
as soon as I posted, it stopped being so easy to repro.
There's some other variable I haven't figured out yet (maybe how the random way that files
get opened in fds/testfiles.c), but it does seem to point at the xattr changes.
I'll poke at it some more tomorrow.