On Thu, Nov 12, 2026 at 05:37:06PM +0100, Christian Brauner wrote: > A capture kernel reads the memory of the crashed kernel. That memory > may have uncorrectable errors in it. Which is likely also what murdered > the first kernel. > > On x86 a machine check in the copy that /proc/vmcore does out of an old > page panics the capture kernel. On book3s64 the read() comes up short > and splice() panics. Breno has observed that on a fleet iiuc. The first > kernel dies of a machine check and then there's no vmcore either. > > I had the powerpc half of this as a fix in part 1 of the procfs series > because Chris ran into it there. Breno pointed out that x86 has the same > hole. > > I think that likely makes this a kdump problem and not a procfs problem. > So I moved this out together with the ioremap_cache() fix.
So I'm not super familiar with the machine check stuff. I know that @Linus has some familiarity with this. So I guess a yay or nay would be nice. Not sure if really a localized fix for the architectures that have mc support makes more sense. A common helper seems less fragile to me.
