S.Çag(lar Onur wrote:
12 Eki 2006 Per 10:28 tarihinde, Gerd Hoffmann s,unlar? yazm?s,t?:
Try switching the vmware configuration to "other OS". This turns off
os-specific binary patching. The alternatives code might have broken
assumptions vmware does about the linux kernel code ...
I did before, i tried these combinations
* Guest Os: Linux, Version: Other Linux 2.6.x kernel
* Guest Os: Linux, Version: Other Linux
* Guest Os: Other, Version: Other
all of them ends up with panic.
We don't do any binary patching. In general, most of the guest OS types
turn on various performance hints or activate fairly expensive
workarounds to known OS bugs, but they don't make the system less
correct by limiting the functionality available to the OS kernel.
It sounds to me like an interrupt is firing in the alternatives code.
Perhaps some callee is doing a raw local_irq_enable from somewhere
inside here, or nobody took care to disable interrupts in the first
place. You need to have interrupts disabled here.
OMG! When did we start calling alternative_instructions from init with
_after_ local_irq_enable()? This is totally wrong. Even on native
hardware, you can be hit with a timer interrupt in this window where we
are patching the kernel. It does not surprise me that you hit this
repeatedly. It surprises me that other people don't! The kernel has
managed to take enough time to get from the last timer IRQ (likely in
lpj calibration, as you noted in the output) to the alternative patching
point that 90% of the time, another timer IRQ is pending. This can
happen on any machine, not just VMware, and I'm surprised it doesn't
happen with other emulators as well.
It might only happen with SMP because the difficulty of getting good
enough TSC / timer IRQ synchronization during boot increases
exponentially with SMP configurations. And it might pass 10% of the time
because you were lucky enough not to fire off another timer interrupt yet.
My nasty quick patch might not apply - the only tree I've got is a very
hacked 2.6.18-rc6-mm1+local-patches thing, but the fix should be obvious
enough.
Zach
diff -r 2b8ef2e0e25f arch/i386/kernel/alternative.c
--- a/arch/i386/kernel/alternative.c Mon Oct 16 02:30:58 2006 -0700
+++ b/arch/i386/kernel/alternative.c Mon Oct 16 02:34:29 2006 -0700
@@ -389,6 +389,7 @@ extern struct paravirt_patch *__start_pa
void __init alternative_instructions(void)
{
+ unsigned long flags;
if (no_replacement) {
printk(KERN_INFO "(SMP-)alternatives turned off\n");
free_init_pages("SMP alternatives",
@@ -396,6 +397,8 @@ void __init alternative_instructions(voi
(unsigned long)__smp_alt_end);
return;
}
+
+ local_irq_save(flags);
apply_alternatives(__alt_instructions, __alt_instructions_end);
/* switch to patch-once-at-boottime-only mode and free the
@@ -433,4 +436,5 @@ void __init alternative_instructions(voi
alternatives_smp_switch(0);
}
#endif
-}
+ local_irq_restore(flags);
+}
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