Messages in this thread | | | From | "Luck, Tony" <> | Date | Wed, 2 Nov 2011 13:57:26 -0700 | Subject | RE: [PATCH v2] kdump: Fix crash_kexec - smp_send_stop race in panic |
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> Instead of introducing the panic lock, as an alternative we could move > smp_send_stop() to the beginning of panic(). Eric told me that the > function is currently "insufficiently reliable" for that, but perhaps we > could make it more reliable.
That's tough to do. We are in panic because something went horribly wrong somewhere in the kernel - so we can make few assumptions about which subsystems are still working. In the worst case (for this example) our panic was caused by a failure in the code that sends cross-processor interrupts ... so calling that same code to stop the other cpus is likely to run into the same problem - perhaps causing a nested panic.
So what looks like a good fix for some panic scenarios actually makes others worse.
-Tony
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