Re: [PATCH v6 0/2] kexec: keep the next kernel off hardware-poisoned pages

[Bradley Morgan]

On 19 August 2026 10:36:17 BST, Mike Rapoport <rppt@xxxxxxxxxx> wrote:
>On Wed, Aug 12, 2026 at 04:31:50AM -0700, Breno Leitao wrote:
>> Memory failures are common enough on large fleets that kexec regularly
>> lands the next kernel on a frame the memory failure subsystem has
>already
>> marked bad. Patch 2 teaches the segment placement to avoid those frames.
>> 
>> Patch 1 is a prerequisite. locate_mem_hole_top_down() walks candidates
>> downwards without ever checking that the subtraction stays above zero,
>so
>> the walk can wrap and report success with a destination outside of RAM.
>> Patch 2 adds one more downward step to that loop, so the bug is fixed
>> first and both patches rely on the same bail-out.
>
>I queued this for v7.4, the patches will appear in the liveupdate tree
>after the merge window.
> 

Ah, so it'll appear in a maintainers tree after MW?

>> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>
>> ---
>> Changes in v6:
>> - Split the pre-existing top-down underflow out into its own patch, and
>>   drop the "if (poison < kbuf->memsz)" guard from the hwpoison hunk now
>>   that the loop bail-out covers it. (Mike Rapoport, Sashiko)
>> - Reword the changelog: the MCE comes from reading the poison back, not
>>   from the relocation copy writing it, and the placement paragraphs read
>>   better split up. (Mike Rapoport)
>> - Move cond_resched() after the struct page dereference, so the scan
>does
>>   not yield between pfn_to_online_page() and is_page_hwpoison().
>>   (Pratyush Yadav, Sashiko)
>> - Keep cond_resched() per pfn rather than batching it. (Kiryl Shutsemau,
>>   Rik van Riel)
>> - Link to v5:
>https://patch.msgid.link/20260810-kexec_posioned-v5-1-95e1b5e2e656@xxxxxxxxxx
>> 
>> Changes in v5:
>> - Return -EHWPOISON instead of -EADDRNOTAVAIL
>> - Leverage is_page_hwpoison() instead of per-page check
>> - Link to v4:
>https://patch.msgid.link/20260807-kexec_posioned-v4-1-70d57f14625d@xxxxxxxxxx
>> 
>> Changes in v4:
>> - Anchor the top-down hole finder on the first poisoned page in the
>>   window and the bottom-up one on the last, so each jumps clear of the
>>   poison in one step. New range_first_hwpoison(). (Kiryl Shutsemau)
>> - Count a poisoned hugetlb folio in full: the flag lives on the folio,
>>   not on the subpages, so the per-pfn scan missed poisoned tail pages.
>>   (Kiryl Shutsemau)
>> - Link to v3:
>https://patch.msgid.link/20260803-kexec_posioned-v3-1-83aa6ede0351@xxxxxxxxxx
>> 
>> Changes in v3:
>> - Return the address of the last poisoned page in the range, or
>>   PHYS_ADDR_MAX when it is clean, instead of a bool plus an output
>>   parameter. Renamed to range_last_hwpoison(). (Pratyush Yadav)
>> - Add cond_resched() to the scan loop, as a segment can span half of
>>   memory. (Sashiko)
>> - Link to v2:
>https://patch.msgid.link/20260730-kexec_posioned-v2-1-f92d18551f64@xxxxxxxxxx
>> 
>> Changes in v2:
>> - Change from pfn_to_page() to pfn_to_online_page(). (Miaohe Lin)
>> - Return the poisoned address once we find a hit, to avoid the O(n^2)
>>   rescan. (Sashiko)
>> - Link to v1:
>https://patch.msgid.link/20260728-kexec_posioned-v1-1-160c81d180fe@xxxxxxxxxx
>> 
>> To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> To: David Hildenbrand <david@xxxxxxxxxx>
>> To: Lorenzo Stoakes <ljs@xxxxxxxxxx>
>> To: "Liam R. Howlett" <liam@xxxxxxxxxxxxx>
>> To: Vlastimil Babka <vbabka@xxxxxxxxxx>
>> To: Mike Rapoport <rppt@xxxxxxxxxx>
>> To: Suren Baghdasaryan <surenb@xxxxxxxxxx>
>> To: Michal Hocko <mhocko@xxxxxxxx>
>> To: Baoquan He <baoquan.he@xxxxxxxxx>
>> To: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
>> To: Pratyush Yadav <pratyush@xxxxxxxxxx>
>> To: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> To: Naoya Horiguchi <nao.horiguchi@xxxxxxxxx>
>> Cc: linux-mm@xxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> Cc: kexec@xxxxxxxxxxxxxxxxxxx
>> Cc: rmikey@xxxxxxxx
>> Cc: riel@xxxxxxxxxxx
>> 
>> ---
>> Breno Leitao (2):
>>       kexec_file: stop the top-down search before it underflows
>>       kexec: keep the next kernel off hardware-poisoned pages
>> 
>>  include/linux/mm.h  | 14 ++++++++++++++
>>  kernel/kexec_core.c | 10 ++++++++++
>>  kernel/kexec_file.c | 20 +++++++++++++++++++-
>>  mm/memory-failure.c | 40 ++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 83 insertions(+), 1 deletion(-)
>> ---
>> base-commit: c5e32e86ca02b003f86e095d379b38148999293d
>> change-id: 20260727-kexec_posioned-72bb0a4143a0
>> 
>> Best regards,
>> --  
>> Breno Leitao <leitao@xxxxxxxxxx>
>> 
>
>

Thanks!