Messages in this thread | | | Date | Thu, 19 Jun 2008 12:32:42 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] - Increase MAX_APICS for very large x86_64 configs |
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* Ingo Molnar <mingo@elte.hu> wrote:
> > The patch has no effect on any 32-bit kernel. It adds ~4k to the > > size of 64-bit kernels but only if NR_CPUS > 255. > > > > This is a repost of an earlier patch (4/16) that was implicated in a > > random-qa failure. I have not been able to reproduce the failure > > using the same boot args & config. Best guess is that some other > > patch caused random data corruption & this patch was a victim. > > i have just re-tested the previously failing config on tip/master: > > http://redhat.com/~mingo/misc/config-Thu_Apr_17_10_17_14_CEST_2008.bad > http://people.redhat.com/mingo/tip.git/README > > and the good news is that it does not crash on bootup anymore. Perhaps > one of Mike's fixes/improvements did the trick?
unfortunately it didnt last long, -tip randconfig auto-testing found that your patch causes a bootup crash:
[ 0.352022] SMP mode deactivated. [ 0.355356] enabled ExtINT on CPU#0 [ 0.358861] SMP disabled [ 0.361829] BUG: unable to handle kernel NULL pointer dereference at 00000000000008b0 [ 0.364022] IP: [<ffffffff8028127b>] debug_mutex_add_waiter+0x4e/0x61 [ 0.364022] PGD 0 [ 0.364022] Thread overran stack, or stack corrupted
config, log and bzImage can be found here:
http://redhat.com/~mingo/misc/config-Thu_Jun_19_12_10_40_CEST_2008.bad http://redhat.com/~mingo/misc/crash-Thu_Jun_19_12_10_40_CEST_2008.log http://redhat.com/~mingo/misc/bzImage-Thu_Jun_19_12_10_40_CEST_2008.bad
reverting your patch fixes the crash.
if you have trouble reproducing the problem then you should be able to stick the bzImage into any 64-bit PC's /etc/grub.conf (no initrd needed) and it should just crash straight away during bootup.
NOTE: -tip auto-testing randomizes various commonly used boot parameters as well, you can find them in the bootup log:
root=/dev/sda6 console=ttyS0,115200 earlyprintk=serial,ttyS0,115200 debug initcall_debug apic=verbose sysrq_always_enabled ignore_loglevel selinux=0 maxcpus=1 nosmp no_hz=off highres=0 nmi_watchdog=0 noapic nolapic_timer hpet=disable idle=mwait idle=poll highmem=512m nopat notsc acpi=off pci=nomsi
this might be material to reproducing the crash.
NOTE2: the bzImage above will have the above boot parameters auto-appended, no need for you to configure them. But if you build your own kernel from tip/master using the above config you might have to add these boot parameters to the 'kernel' line of /etc/grub.conf to reproduce the crash.
Ingo
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