Re: [PATCH v5 9/9] mm/memory-failure: keep inherited poisoned frames out of the buddy allocator

[Vlastimil Babka (SUSE)]

On 9/15/26 14:53, Breno Leitao wrote:
> When the pages are being given to the allocator, check if they are
> poisoned, and mark them as such.
> 
> Similar to unaccepted memory, hook it in __free_pages_core(), and thus
> the frames never enter the allocator, rather than being taken back out
> of it.
> 
> A block runs up to MAX_PAGE_ORDER and a unit is 2MB, so hold back only
> the frames the table covers and free the rest one at a time. The
> allocator merges them back up, so a unit costs the frames it names, not
> the whole block.
> 
> The frames that are freed go back through accept_and_free_block(), so a
> clean frame in a block that is still unaccepted is accepted first.
> 
> A frame is flagged before its memory block exists, so the per block
> counter is seeded from the page flag when the block is created rather
> than incremented here.
> 
> Suggested-by: Kiryl Shutsemau <kas@xxxxxxxxxx>
> Signed-off-by: Breno Leitao <leitao@xxxxxxxxxx>

Acked-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>

> ---
>  mm/page_alloc.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index b07b5f4751cb95..cca67a2702a421 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1597,6 +1597,25 @@ static void __meminit accept_and_free_block(struct page *page,
>  	__free_pages_ok(page, order, FPI_TO_TAIL);
>  }
>  
> +static void __meminit free_poisoned_block(struct page *page, unsigned int order,
> +					  enum meminit_context context)
> +{
> +	unsigned long i, nr_pages = 1UL << order;
> +
> +	for (i = 0; i < nr_pages; i++) {
> +		struct page *p = page + i;
> +		phys_addr_t phys = page_to_phys(p);
> +
> +		if (range_contains_poisoned_memory(phys, PAGE_SIZE)) {
> +			hwpoison_boot_page(p, context);
> +			continue;
> +		}
> +
> +		/* this part of the block is not poisoned */
> +		accept_and_free_block(p, 0);
> +	}
> +}
> +
>  void __meminit __free_pages_core(struct page *page, unsigned int order,
>  		enum meminit_context context)
>  {
> @@ -1631,6 +1650,13 @@ void __meminit __free_pages_core(struct page *page, unsigned int order,
>  		atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
>  	}
>  
> +	/* First: a block parked by __free_unaccepted() never returns here. */
> +	if (range_contains_poisoned_memory(page_to_phys(page),
> +					   PAGE_SIZE << order)) {
> +		free_poisoned_block(page, order, context);
> +		return;
> +	}
> +
>  	accept_and_free_block(page, order);
>  }
>  
>