[merged mm-stable] mm-memory-failure-drop-dead-error_states-entry-for-reserved-pages.patch removed from -mm tree

The quilt patch titled
     Subject: mm/memory-failure: drop dead error_states[] entry for reserved pages
has been removed from the -mm tree.  Its filename was
     mm-memory-failure-drop-dead-error_states-entry-for-reserved-pages.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Breno Leitao <[email protected]>
Subject: mm/memory-failure: drop dead error_states[] entry for reserved pages
Date: Tue, 30 Jun 2026 05:46:04 -0700

Patch series "mm/memory-failure: add panic option for unrecoverable
pages", v10.

A multi-bit ECC error on a kernel-owned page that the memory failure
handler cannot recover is currently swallowed: PG_hwpoison is set, the
event is logged, and the kernel keeps running.  The corrupted memory
remains accessible to the kernel and either drives silent data corruption
or surfaces seconds-to-minutes later as an apparently unrelated crash.  In
a large fleet that delayed, unattributable crash turns into significant
engineering effort to root-cause; in a kdump configuration, by the time
the crash happens the original error context (faulting PFN, MCE/GHES
record, page state) is long gone.

This series adds an opt-in sysctl,
vm.panic_on_unrecoverable_memory_failure, that converts an unrecoverable
kernel-page hwpoison event into an immediate panic with a clean
dmesg/vmcore that still contains the original failure context.  The
default is disabled so existing workloads see no change.

There is a selftest that test different cases, and I tested it using
the following variants:

  ┌─────────┬──────────┬───────────────────────────────────────────────────────────┐
  │ Variant │   PFN    │                          Result                           │
  ├─────────┼──────────┼───────────────────────────────────────────────────────────┤
  │ rodata  │ 0x2600   │ Panic with "Memory failure: 0x2600: unrecoverable page"   │
  ├─────────┼──────────┼───────────────────────────────────────────────────────────┤
  │ slab    │ 0x100032 │ Panic with "Memory failure: 0x100032: unrecoverable page" │
  ├─────────┼──────────┼───────────────────────────────────────────────────────────┤
  │ pgtable │ 0x100000 │ Panic with "Memory failure: 0x100000: unrecoverable page" │
  └─────────┴──────────┴───────────────────────────────────────────────────────────┘

Each one shows the same call trace, exactly the path the series builds:

  hard_offline_page_store
    → memory_failure
      → action_result
        → panic("Memory failure: %#lx: unrecoverable page")


This patch (of 5):

The first entry of error_states[],

	{ reserved,	reserved,	MF_MSG_KERNEL,	me_kernel },

is unreachable.  identify_page_state() has two callers, and neither
one can dispatch a PG_reserved page to me_kernel():

  * memory_failure() reaches identify_page_state() only after
    get_hwpoison_page() returned 1.  get_any_page() reaches that
    return only via __get_hwpoison_page(), which only takes a
    refcount when the page is HWPoisonHandlable().
    HWPoisonHandlable() is an allowlist for LRU, free-buddy, and
    (for soft-offline) movable_ops pages -- PG_reserved pages do
    not satisfy any of these, so they fail with -EBUSY/-EIO long
    before identify_page_state() runs.

  * try_memory_failure_hugetlb() reaches identify_page_state() only
    via the MF_HUGETLB_IN_USED branch, where the page is necessarily
    a hugetlb folio.  hugetlb folios don't carry PG_reserved at that
    point: hugetlb_folio_init_vmemmap() calls __folio_clear_reserved()
    during init, so the reserved entry would not match even if it
    were still present.

me_kernel() never executes and the entry exists only to be matched
against by code that cannot see it.

Drop the entry, the me_kernel() helper, and the now-unused
"reserved" macro.  Leave the MF_MSG_KERNEL enum value in place: it
remains part of the tracepoint and pr_err() string tables, and
follow-on work to classify unrecoverable kernel pages can reuse it
without churning the user-visible enum.

No functional change.

Link: https://lore.kernel.org/[email protected]
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Breno Leitao <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Acked-by: David Hildenbrand (Arm) <[email protected]>
Reviewed-by: Lance Yang <[email protected]>
Acked-by: Miaohe Lin <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: "Masami Hiramatsu (Google)" <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/memory-failure.c |   14 --------------
 1 file changed, 14 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-drop-dead-error_states-entry-for-reserved-pages
+++ a/mm/memory-failure.c
@@ -982,17 +982,6 @@ static bool has_extra_refcount(struct pa
 }
 
 /*
- * Error hit kernel page.
- * Do nothing, try to be lucky and not touch this instead. For a few cases we
- * could be more sophisticated.
- */
-static int me_kernel(struct page_state *ps, struct page *p)
-{
-	unlock_page(p);
-	return MF_IGNORED;
-}
-
-/*
  * Page in unknown state. Do nothing.
  * This is a catch-all in case we fail to make sense of the page state.
  */
@@ -1200,10 +1189,8 @@ static int me_huge_page(struct page_stat
 #define mlock		(1UL << PG_mlocked)
 #define lru		(1UL << PG_lru)
 #define head		(1UL << PG_head)
-#define reserved	(1UL << PG_reserved)
 
 static struct page_state error_states[] = {
-	{ reserved,	reserved,	MF_MSG_KERNEL,	me_kernel },
 	/*
 	 * free pages are specially detected outside this table:
 	 * PG_buddy pages only make a small fraction of all free pages.
@@ -1235,7 +1222,6 @@ static struct page_state error_states[]
 #undef mlock
 #undef lru
 #undef head
-#undef reserved
 
 static void update_per_node_mf_stats(unsigned long pfn,
 				     enum mf_result result)
_

Patches currently in -mm which might be from [email protected] are

mm-migrate-report-rcu-tasks-quiescent-states-in-migrate_pages_batch.patch
mm-kmemleak-report-leaks-only-after-n-consecutive-unreferenced-scans.patch
mm-kmemleak-factor-leak-confirmation-into-a-helper.patch
selftests-mm-test-kmemleaks-n-consecutive-scan-leak-confirmation.patch
radix-tree-fix-kmemleak-false-positives-on-tree-head-reassignment.patch
mm-kmemleak-report-rcu-tasks-quiescent-states-during-the-scan.patch
mm-kmemleak-default-min_unref_scans-to-2-for-verbose-auto-scan.patch
documentation-kmemleak-document-the-conditional-min_unref_scans-default.patch
selftests-mm-kmemleak-drop-stale-min_unref_scans-default-from-comments.patch