Re: Kernel panic with Matsushita CD-ROM in 1.99.11

Linus Torvalds (torvalds@cs.helsinki.fi)
Wed, 5 Jun 1996 08:51:45 +0300 (EET DST)

On Tue, 4 Jun 1996, emoenke wrote:
>
> Hi Steffen Zahn,
>
> >Jun 4 18:21:04 zahn linux: Kernel panic: Matsushita CD-ROM controller #1: block not locked
>
> I suppose it is a compiler bug. I saw it sporadically with gcc-2.7.0,
> and it seems gone under gcc-2.7.2.
> Under 2.7.0, I could eliminate it by just putting additional, but "neutral"
> statements around that "decision spot" in ll_rw_blk.c.

No, it might well be a real kernel bug. The low-level brw_page() stuff got
changed to take care of _another_ potential bug in 1.99.11, and that made
this older bug re-surface again. I think I nailed them both correctly in
1.99.12 (knock wood). I haven't actually ever seen any of the behaviour
that some people report, but source code debugging certainly indicates
that there could have been a real problem there..

In short, could you take a look at 2.0pre12, and see if the problem is
gone? It should have happened _only_ under very heavy load (although a
slow device like a CD-ROM or a floppy might have made it happen a lot
more easily).

Linus