Re: [PATCH] ACPI: APEI: GHES: Don't offline huge pages just because BIOS asked

[Mike Rapoport <rppt@kernel.org>]

On Thu, Sep 04, 2025 at 08:57:20AM -0700, Tony Luck wrote:
> BIOS can supply a GHES error record that reports that the corrected
> error threshold has been exceeded. Linux will attempt to soft offline
> the page in response.
> 
> But "exceeded threshold" has many interpretations. Some BIOS versions
> accumulate error counts per-rank, and then report threshold exceeded
> when the number of errors crosses a threshold for the rank. Taking
> a page offline in this case is unlikely to solve any problems. But
> losing a 4KB page will have little impact on the overall system.
> 
> On the other hand, taking a huge page offline will have significant
> impact (and still not solve any problems).
> 
> Check if the GHES record refers to a huge page. Skip the offline
> process if the page is huge.
> 
> Reported-by: Shawn Fan <shawn.fan@intel.com>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
>  drivers/acpi/apei/ghes.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index a0d54993edb3..bacfebdd4969 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -540,8 +540,16 @@ static bool ghes_handle_memory_failure(struct acpi_hest_generic_data *gdata,
>  
>  	/* iff following two events can be handled properly by now */
>  	if (sec_sev == GHES_SEV_CORRECTED &&
> -	    (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED))
> +	    (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED)) {
> +		unsigned long pfn = PHYS_PFN(mem_err->physical_addr);
> +		struct page *page = pfn_to_page(pfn);
> +		struct folio *folio = page_folio(page);

There's pfn_folio(), saves a line :)

> +
> +		if (folio_test_hugetlb(folio))
> +			return false;
> +
>  		flags = MF_SOFT_OFFLINE;
> +	}
>  	if (sev == GHES_SEV_RECOVERABLE && sec_sev == GHES_SEV_RECOVERABLE)
>  		flags = sync ? MF_ACTION_REQUIRED : 0;
>  
> -- 
> 2.51.0
> 

-- 
Sincerely yours,
Mike.