[PATCH v6 3/7] mm/memory-failure: add hwpoison_boot_page() to flag an inherited frame

[sashiko-bot at kernel.org]

> A kernel that kexecs inherits the frames its predecessor found
> hardware-poisoned. It has to carry them as PG_hwpoison in its own memmap,
> so that everything that already understands the flag covers them,
> including the kexec segment placement check.
> 
> Add a helper that sets the flag and counts the frame in
> num_poisoned_pages. It runs while the memmap is initialised, before
> memory_dev_init() has run. memblk_nr_poison_inc() divides by
> sections_per_block, which memory_dev_init() sets, so the helper
> increments num_poisoned_pages itself instead of calling
> num_poisoned_pages_inc().
> 
> An inherited frame is a hardware failure like any other, so the helper
> sets hw_memory_failure. Without it, unpoison_memory() accepts the frame,
> clears the flag and drops the last reference, which frees a frame that
> is still bad.
> 
> The helper also counts the frame as managed, as a frame that fails at
> run time stays counted. Memory offlining subtracts every frame of the
> block that is not PageOffline, so a frame that was never counted leaves
> the managed page count too low after an offline.
> 
> The per-node memory failure statistics are not updated. This kernel
> handled no failure, it only inherited one.
> 
> Signed-off-by: Breno Leitao <leitao at debian.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261016-hwpoison-kho-v6-0-f304255147da@debian.org?part=3