[PATCH v2] ACPI: APEI: GHES: Don't offline huge pages just because BIOS asked

["Luck, Tony" <tony.luck@intel.com>]

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>
---

Changes since v1:

* Mike Rapoport: Save a line by using pfn_folio()

* Liam R. Howlett: Don't return false. Continue to rest of function.
  [Yes, code could use "else if" since "sec_sev" can't be both GHES_SEV_CORRECTED
   and GHES_SEV_RECOVERABLE. But I left that alone for now as unrelated to
   this change]

 drivers/acpi/apei/ghes.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index a0d54993edb3..92a767fa7ca4 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -540,8 +540,14 @@ 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))
-		flags = MF_SOFT_OFFLINE;
+	    (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED)) {
+		unsigned long pfn = PHYS_PFN(mem_err->physical_addr);
+		struct folio *folio = pfn_folio(pfn);
+
+		/* Only try to offline non-huge pages */
+		if (!folio_test_hugetlb(folio))
+			flags = MF_SOFT_OFFLINE;
+	}
 	if (sev == GHES_SEV_RECOVERABLE && sec_sev == GHES_SEV_RECOVERABLE)
 		flags = sync ? MF_ACTION_REQUIRED : 0;
 
-- 
2.51.0