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

Linus Torvalds
2009-10-01T01:57:43Z

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..

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

Linus