Messages in this thread | | | Date | Thu, 5 Jun 2008 12:22:22 +0200 | From | Ingo Molnar <> | Subject | [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area |
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* Mike Travis <travis@sgi.com> wrote:
> * Declare the pda as a per cpu variable. > > * Make the x86_64 per cpu area start at zero. > > * Since the pda is now the first element of the per_cpu area, cpu_pda() > is no longer needed and per_cpu() can be used instead. This also makes > the _cpu_pda[] table obsolete. > > * Since %gs is pointing to the pda, it will then also point to the per cpu > variables and can be accessed thusly: > > %gs:[&per_cpu_xxxx - __per_cpu_start] > > Based on linux-2.6.tip
-tip testing found an instantaneous reboot crash on 64-bit x86, with this config:
http://redhat.com/~mingo/misc/config-Thu_Jun__5_11_43_51_CEST_2008.bad
there is no boot log as the instantaneous reboot happens before anything is printed to the (early-) serial console. I have bisected it down to:
| 7670dc09e89a2b151a1cf49eccebc07c41c2ce9f is first bad commit | commit 7670dc09e89a2b151a1cf49eccebc07c41c2ce9f | Author: Mike Travis <travis@sgi.com> | Date: Tue Jun 3 17:30:21 2008 -0700 | | x86_64: Fold pda into per cpu area
the big problem is not just this crash, but that the patch is _way_ too big:
arch/x86/Kconfig | 3 + arch/x86/kernel/head64.c | 34 ++++++-------- arch/x86/kernel/irq_64.c | 36 ++++++++------- arch/x86/kernel/setup.c | 90 ++++++++++++--------------------------- arch/x86/kernel/setup64.c | 5 -- arch/x86/kernel/smpboot.c | 51 ---------------------- arch/x86/kernel/traps_64.c | 11 +++- arch/x86/kernel/vmlinux_64.lds.S | 1 include/asm-x86/percpu.h | 48 ++++++-------------- 9 files changed, 89 insertions(+), 190 deletions(-)
considering the danger involved, this is just way too large, and there's no reasonable debugging i can do in the bisection to narrow it down any further.
Please resubmit with the bug fixed and with a proper splitup, the more patches you manage to create, the better. For a dangerous code area like this, with a track record of frequent breakages in the past, i would not mind a "one line of code changed per patch" splitup either. (Feel free to send a git tree link for us to try as well.)
Ingo
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