Re: kexec/kdump kernel fails to start

From: Yinghai Lu
Date: Tue Sep 04 2012 - 15:01:54 EST


On Tue, Sep 4, 2012 at 10:32 AM, Flavio Leitner <fbl@xxxxxxxxxx> wrote:
> Hi folks,
>
> I have system that no longer boots kdump kernel. Basically,
>
> # echo c > /proc/sysrq-trigger
>
> to dump a vmcore doesn't work. It just hangs after showing the usual
> panic messages. I've bisected the problem and the commit introducing
> the issue is the one below.
>
> Any idea?
>
> commit 722bc6b16771ed80871e1fd81c86d3627dda2ac8
> Author: WANG Cong <xiyou.wangcong@xxxxxxxxx> 2012-03-05 20:05:13
> Committer: Ingo Molnar <mingo@xxxxxxx> 2012-03-06 05:38:26
> Parent: 550cf00dbc8ee402bef71628cb71246493dd4500 (Merge tag 'mmc-fixes-for-3.3' of git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc)
> Child: a6fca40f1d7f3e232c9de27c1cebbb9f787fbc4f (x86, tlb: Switch cr3 in leave_mm() only when needed)
> Branches: master, remotes/origin/master
> Follows: v3.3-rc6
> Precedes: v3.5-rc1
>
> x86/mm: Fix the size calculation of mapping tables
>
> For machines that enable PSE, the first 2/4M memory region still uses
> 4K pages, so needs more PTEs in this case, but
> find_early_table_space() doesn't count this.
>
> This patch fixes it.
>
> The bug was found via code review, no misbehavior of the kernel
> was observed.

maybe just revert the offending commit?

Thanks

Yinghai
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