* Anton Blanchard [off-list ref] wrote:

Every now and then I end up with an undebuggable issue 
because multiple CPUs hit something at the same time and 
everything is interleaved:

        CR: 48000082  XER: 00000000
        ,RI
        c0000003dc72fd10
        ,LE
        d0000000065b84e8
        Instruction dump:
        MSR: 8000000100029033

Very annoying.

Some architectures already have their own recursive 
locking for oopses and we have another version for 
serialising dump_stack.

Create a common version and use it everywhere (oopses, 
BUGs, WARNs, dump_stack, soft lockups and hard lockups). 

Dunno. I've had cases where the simultaneity of the oopses 
(i.e. their garbled nature) gave me the clue about the type 
of race to expect.

To still get that information: instead of taking a 
serializing spinlock (or in addition to it), it would be 
nice to at least preserve the true time order of the 
incidents, at minimum by generating a global count for 
oopses/warnings (a bit like the oops count # currently), 
and to gather it first - before taking any spinlocks.

Thanks,

	Ingo