On Mon 08-07-13 21:06:58, Guenter Roeck wrote:
> On Mon, Jul 08, 2013 at 11:35:10PM -0400, Theodore Ts'o wrote:
> > On Mon, Jul 08, 2013 at 11:38:29AM -0700, Guenter Roeck wrote:
> > > Hi,
> > >
> > > seen this morning with a brand new top-of-tree kernel (as of last night) plus a
> > > couple of patches I am working on.
> > >
> > > Due to my changes, there is a slight chance that the problem is not due to an
> > > upstream bug, but I think that is quite unlikely (my changes are unrelated
> > > to file system code).
> > >
> > > If there is anything I can help to track this down, please let me know.
> > >
> > > [13071.291013] ------------[ cut here ]------------
> > > [13071.291021] WARNING: at fs/ext4/inode.c:230 ext4_evict_inode+0x41b/0x510()
> >
> > Hmm, this warning was added by commit 5dc23bdd5: ext4: remove
> > ext4_ioend_wait().
> >
> > What sort of work load are you running on this machine? Do you know
> > what might have triggered it?
> >
> My nightly kernel builds were running at the time. This is a sequence of git
> clone/checkout operations followed by builds for several targets.
>
> I have the same kernel running on three systems, but this only happened on the
> build machine, and I have not seen it again during the day.
>
> I'll let you know if it happens again tonight.
Thanks for report. I think I see what's going on. I think we completed
bio directly in ext4_end_bio() (as it didn't need unwritten conversion) but
io_end is released only a bit later which can race with ext4_evict_inode()
as:
CPU1 CPU2
ext4_end_bio() ext4_evict_inode()
ext4_finish_bio()
end_page_writeback();
truncate_inode_pages()
evict page
WARN_ON(i_ioend_count > 0);
ext4_put_io_end_defer()
ext4_release_io_end()
dec i_ioend_count
This seems harmless. I'll see if I can easily fix this to make the warning
still useful. If not, I'll just rip out i_ioend_count completely as it's
there only as a sanity check until the new code settles down...
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
