Re: next/mmotm: ext4 causes !rwsem_is_locked warnings

From: Theodore Ts'o
Date: Thu Sep 27 2012 - 17:27:06 EST


On Thu, Sep 27, 2012 at 02:05:00PM -0700, Hugh Dickins wrote:
> Hi Ted,
>
> mmotm (or next) now gives me lots of WARNING at fs/fs-writeback.c:1312 from
> writeback_inodes_sb_nr(). That's WARN_ON(!rwsem_is_locked(&sb->s_umount))
> (some useful safety from hch) in writeback_inodes_sb_nr().
>
> Your commit 40e684e5c597a98996cf4616e31fb2581ec82060
> "ext4: fix potential deadlock in ext4_nonda_switch()" needs more change
> to fs/fs-writeback.c. I guess I'm the only one using a nearly full ext4.
>
> I am, of course, applying the patch at the bottom to my tree for now;
> but I think you'd do better not to eliminate that check. Maybe add a
> special wb_reason for your case, and skip rwsem check in that case.

Yeah, we were just discussing this on another thread. I didn't think
of the option of creating a new special wb_reason option, but that's a
much better option than the other ones I had been considering, so I
think I will give that a try. Thanks for the suggestion!!

- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/