Re: [PATCH] sysrq, kdump: fix regression, revert "simplify sysrq-c handler"

[Eric W. Biederman]

Lai Jiangshan <laijs@xxxxxxxxxxxxxx> writes:

> 1) This fix breaks our tools.
>       This fix changes the ABI. panic_on_oops is default 0,
>    and a lots system do not specify the boot option "panic",
>    thus, Sysrq-c will not cause CrashDump(Kdump) as expected.

How does it break your tools?

> 2) When CONFIG_KEXEC=n, Sysrq-c should become an invalid
>    command like Sysrq-D(CONFIG_LOCKDEP, show-all-locks).
>    But this fix makes it a valid command and let it do a
>    hazard thing: cause a page fault(NULL dereference) in kernel.
>
> So, we revert this fix.

The idea was to extend sysrq-d to also be a way of testing NULL
pointer dereferences.  How is that a bad idea?

Eric
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