[PATCH v2] mm/memory-failure: Fix redundant updates for already poisoned pages

[Kyle Meyer <kyle.meyer@hpe.com>]

Duplicate memory errors can be reported by multiple sources.

Passing an already poisoned page to action_result() causes issues:

* The amount of hardware corrupted memory is incorrectly updated.
* Per NUMA node MF stats are incorrectly updated.
* Redundant "already poisoned" messages are printed.

Avoid those issues by:

* Skipping hardware corrupted memory updates for already poisoned pages.
* Skipping per NUMA node MF stats updates for already poisoned pages.
* Dropping redundant "already poisoned" messages.

Make MF_MSG_ALREADY_POISONED consistent with other action_page_types and
make calls to action_result() consistent for already poisoned
normal pages and huge pages.

Fixes: b8b9488d50b7 ("mm/memory-failure: improve memory failure action_result messages")
Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
---

v1 -> v2:
 * Continue passing poisoned pages to action_result() with MF_FAILED but don't
update anything.
 * https://lore.kernel.org/all/20250821164445.14467-1-kyle.meyer@hpe.com

---
 mm/memory-failure.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index fc30ca4804bf..10b3c281c2ae 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -956,7 +956,7 @@ static const char * const action_page_types[] = {
 	[MF_MSG_BUDDY]			= "free buddy page",
 	[MF_MSG_DAX]			= "dax page",
 	[MF_MSG_UNSPLIT_THP]		= "unsplit thp",
-	[MF_MSG_ALREADY_POISONED]	= "already poisoned",
+	[MF_MSG_ALREADY_POISONED]	= "already poisoned page",
 	[MF_MSG_UNKNOWN]		= "unknown page",
 };
 
@@ -1349,9 +1349,10 @@ static int action_result(unsigned long pfn, enum mf_action_page_type type,
 {
 	trace_memory_failure_event(pfn, type, result);
 
-	num_poisoned_pages_inc(pfn);
-
-	update_per_node_mf_stats(pfn, result);
+	if (type != MF_MSG_ALREADY_POISONED) {
+		num_poisoned_pages_inc(pfn);
+		update_per_node_mf_stats(pfn, result);
+	}
 
 	pr_err("%#lx: recovery action for %s: %s\n",
 		pfn, action_page_types[type], action_name[result]);
@@ -2094,12 +2095,11 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 		*hugetlb = 0;
 		return 0;
 	} else if (res == -EHWPOISON) {
-		pr_err("%#lx: already hardware poisoned\n", pfn);
 		if (flags & MF_ACTION_REQUIRED) {
 			folio = page_folio(p);
 			res = kill_accessing_process(current, folio_pfn(folio), flags);
-			action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED);
 		}
+		action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED);
 		return res;
 	} else if (res == -EBUSY) {
 		if (!(flags & MF_NO_RETRY)) {
@@ -2285,7 +2285,6 @@ int memory_failure(unsigned long pfn, int flags)
 		goto unlock_mutex;
 
 	if (TestSetPageHWPoison(p)) {
-		pr_err("%#lx: already hardware poisoned\n", pfn);
 		res = -EHWPOISON;
 		if (flags & MF_ACTION_REQUIRED)
 			res = kill_accessing_process(current, pfn, flags);
-- 
2.50.1