Re: [Kernel BUG] ext4 for v2.6.32 round II

Markus Trippelsdorf
2009-10-01T02:15:30Z

On Wed, Sep 30, 2009 at 06:57:00PM -0700, Linus Torvalds wrote:
>
>
> On Thu, 1 Oct 2009, Markus Trippelsdorf wrote:
> >
> > Running latest git I get the following kernel BUG message:
> >
> > ------------[ cut here ]------------
> > Kernel BUG at ffffffff810efa89 [verbose debug info unavailable]
>
> You really shouldn't turn off verbose debug info unless you are _really_
> tight on memory in some embedded device. It's not that complex, nor does
> it use a lot of memory, and it makes the error report much harder to
> figure out when the verbose debug output information isn't available.
>
> But in this case I can do it by just looking at the function/offset:
>
> > RIP: 0010:[<ffffffff810efa89>] [<ffffffff810efa89>] ext4_num_dirty_pages+0x113/0x213
>
> The only BUG_ON() that seems relevant in that function (at least with the
> config I tried with) ends up being
>
> fs/ext4/inode.c:1184
>
> in my sources, which is from "page_buffers(page)", which has a
>
> BUG_ON(!PagePrivate(page));
>
> in it. And that would have been much easier to figure out if you had had
> CONFIG_DEBUG_BUGVERBOSE enabled..
>

You're right (with CONFIG_DEBUG_BUGVERBOSE=y):

------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:1184!
...

> Now over to the ext4 people to actually hopefully _solve_ the bug. Maybe
> bisection would help.

--
Markus