Messages in this thread | | | Date | Sun, 20 Jul 2008 00:27:26 +0200 | From | "Vegard Nossum" <> | Subject | Re: linux-next: Tree for July 18: warning at kernel/lockdep.c:2068 trace_hardirqs_on_caller |
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On Sun, Jul 20, 2008 at 12:17 AM, Greg KH <gregkh@suse.de> wrote: > On Sat, Jul 19, 2008 at 02:59:12PM +0200, Vegard Nossum wrote: >> On Sat, Jul 19, 2008 at 11:55 AM, Vegard Nossum <vegard.nossum@gmail.com> wrote: >> > What I don't get here is how SLUB can be used this early in the boot >> > process. Notice that this is still miles away from the >> > >> > SLUB: Genslabs=12, HWalign=128, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 >> > >> > line, which comes much later. And that kobject_init() _is_ calling >> > kzalloc() via verify_dynamic_kobject_allocation(). Isn't this an >> > error? >> > >> > (Unfortunately, my "git log" doesn't turn up any recent changes for >> > any of the affected code paths here.) >> >> Ehe... and this is the reason why: The code was added by this patch: >> >> commit 0e3638d1e04040121af00195f7e4628078246489 >> Author: Dave Hansen <haveblue@us.ibm.com> >> Date: Thu Mar 16 17:30:16 2006 -0800 >> >> warn when statically-allocated kobjects are used >> >> ..which only exists in -next. Is that just a truly ancient patch, or >> did somebody forget to adjust their clock? > > It is truely a very old patch, that only lives in my tree, and currently > isn't planned to go to Linus any year soon. > > But it has a very long history of living in the -mm tree, and finding > real bugs, it's just not "safe" enough to go to Linus's tree. Unless > you think it is?
Hm. In this case, the patch is not even reporting a problem, it is in fact in error itself.
The problem is that it calls kzalloc() before the slab caches have been set up. (Yes, it's a wonder that nothing crashed.) I can only suggest the addendum
if (!slab_is_available()) return;
Vegard
-- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036
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