Re: [PATCH v5 7/9] drivers/base/memory: count inherited poisoned frames into the block

[Kiryl Shutsemau]

On Tue, Sep 22, 2026 at 01:33:51PM +0200, David Hildenbrand (Arm) wrote:
> On 9/21/26 16:31, Breno Leitao wrote:
> > On Fri, Sep 18, 2026 at 10:16:25PM +0200, David Hildenbrand (Arm) wrote:
> >> On 9/18/26 17:22, Breno Leitao wrote:
> >>>
> >>> Right, we have two source for poisoned page information, today.
> >>>
> >>> 1) LINUX_EFI_POISONED_MEMORY: Used to track memory block that got
> >>>    poisioned, and will be passed around during kexec.
> >>> 2) PG_hwpoison on struct page: Used by the memory subsystem to avoid
> >>>    touching it.
> >>
> >> How are both kept in sync? See below.
> > 
> > The EFI table is only written when there is a memory failure. That is
> > the only thing that writes to it:
> > 
> > 	action_result() -> efi_hwpoison_record_pfn() -> set_bit()
> > 
> > You can see it on patch "mm/memory-failure: efi: record
> > hardware-poisoned frames into the poisoned-memory table"
> > 
> > Then, when the kernel kexecs into a second kernel, the EFI config table
> > is queried and the pages are poisoned from it at boot, as they are
> > getting into the buddy allocator, in __free_pages_core().
> 
> I am not sure that is really the right place. That means we only poison free
> memory. Shouldn't we poison as soon as we initialize the memmap, and check
> whether any memblock allocations ended up on that poisoned memory and bail out?

__free_pages_core() is how we hand over pages from memblock to page allocator
initially -- from memblock_free_pages(), deferred_free_pages() and
hotplug. It is the right place to never allow them on free lists.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov