On Thu, May 26, 2011 at 07:32:57PM +0200, Andi Kleen wrote: > On Thu, May 26, 2011 at 10:53:05PM +0530, K.Prasad wrote: > > > > slimdump: Capture slimdump for fatal MCE generated crashes > > > > System crashes resulting from fatal hardware errors (such as MCE) don't need > > all the contents from crashing-kernel's memory. Generate a new 'slimdump' that > > retains only essential information while discarding the old memory. > > While this is a good idea, note there may be still poisoned lines > in memory that haven't resulted in a machine check yet, but could > still be fatal when read after a full crash dump for some other > reason. > True, this patch does not handle the discovery of old poisoned lines/new memory errors that may occur when inside the kdump kernel. > So you still need > > http://git.kernel.org/?p=linux/kernel/git/ak/linux-mce-2.6.git;a=commit;h=fe61906edce9e70d02481a77a617ba1397573dce > and > http://git.kernel.org/?p=linux/kernel/git/ak/linux-mce-2.6.git;a=commit;h=cb58f049ae6709ddbab71be199390dc6852018cd > > in addition. > > -Andi So, there could be (atleast) two ways to handle fatal MCEs in kdump kernel: - To disable MCE exceptions as done by the patches cited above. However the result of a read operation on corrupted memory is unknown and the system behaviour is undefined. We're unsure if this is a safe thing to do. - To disable capture of kdump (when panic is invoked from) inside kdump kernel and simply reboot the system. Since the chance of memory error inside kdump kernel (which runs for a very short duration) is rare, I think this solution is preferrable. Let me know your thoughts on this. Thanks, K.Prasad
