On Tue, 2011-11-01 at 16:04 -0400, Don Zickus wrote: > On Mon, Oct 31, 2011 at 01:34:19PM +0100, Michael Holzheu wrote: > > Hello Andrew, hello linux-arch, > > > > > Well OK. Maybe some architectures do have this problem - who would > > > notice? If that is the case, we just made the failure cases much more > > > common. Could you check, please? > > > > @linux-arch: > > > > This patch introduces a spinlock to prevent parallel execution of the > > panic code. Andrew pointed out that this might be a problem for > > architectures that can't do smp_send_stop() on remote CPUs that have > > interrupts disabled. When irq-disabled CPUs execute panic() in parallel, > > we then would have looping CPUs. > > x86 has such problem and I posted a patch recently to fix it > > https://lkml.org/lkml/2011/10/13/426 Ok good, so with this patch x86 has no problem with the panic spinlock. Anybody else? 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. Michael
