On Wed, 2026-06-24 at 15:40 +0200, Pratyush Yadav wrote: > > Also, what happens on cold reboot? If the HW does not remember bad > pages, won't the kernel be in the same position? How does it know the > bad pages on a cold boot?
Some modern server hardware will simply unmap known bad pages from the physical page map, so they will not be exposed to the OS after a cold reboot. The hardware keeps a log of uncorrectable memory errors somewhere in memory, for example in the SEL. > > > > > > This PoC > > ======== > > > > * Makes hardware-poisoned pages survive a kexec, using KHO (Kexec > > HandOver) to carry the poison list between kernels. > > > > * Producer: hooks num_poisoned_pages_inc()/_sub() - the single > > chokepoint for every poison/unpoison event - and records each > > poisoned PFN into a vmalloc array that KHO preserves across the > > kexec, described by a small versioned "hwpoison" subtree. > > More of an implementation detail, but with vmalloc array, what if you > have too many poisoned pages? > > If a very large amount of memory is broken, you should probably just repair the hardware. Page poisoning is good for localized memory failures, but not for failures that extend across much of a memory chip. > > > -- All Rights Reversed.
