The previous patch teaches get_any_page() to return -ENOTRECOVERABLE for stable unhandlable kernel pages (PG_reserved, slab, page tables, large-kmalloc). memory_failure() still folds every negative return into MF_MSG_GET_HWPOISON, so callers that want to react to the unrecoverable cases (a panic option, smarter logging) cannot tell them apart from transient page-allocator races.
Turn the post-call branch into a switch over the get_hwpoison_page() return code: map -ENOTRECOVERABLE to MF_MSG_KERNEL and any other negative return to MF_MSG_GET_HWPOISON. case 0 keeps the existing free-buddy / kernel-high-order handling and case 1 falls through to the rest of memory_failure() unchanged. The MF_MSG_KERNEL label and tracepoint string are kept as "reserved kernel page" to avoid breaking userspace tools that match on those literals; the enum value still adequately tags the failure even though it now also covers slab, page tables and large-kmalloc pages. Suggested-by: David Hildenbrand <[email protected]> Signed-off-by: Breno Leitao <[email protected]> --- mm/memory-failure.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 8f63bdfeff8f..14c0a958638c 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2426,7 +2426,8 @@ int memory_failure(unsigned long pfn, int flags) * that may make page_ref_freeze()/page_ref_unfreeze() mismatch. */ res = get_hwpoison_page(p, flags); - if (!res) { + switch (res) { + case 0: if (is_free_buddy_page(p)) { if (take_page_off_buddy(p)) { page_ref_inc(p); @@ -2445,7 +2446,19 @@ int memory_failure(unsigned long pfn, int flags) res = action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED); } goto unlock_mutex; - } else if (res < 0) { + case 1: + /* Got a refcount on a handlable page. */ + break; + case -ENOTRECOVERABLE: + /* + * Stable unhandlable kernel-owned page (PG_reserved, + * slab, page tables, large-kmalloc). + * No recovery possible. + */ + res = action_result(pfn, MF_MSG_KERNEL, MF_IGNORED); + goto unlock_mutex; + default: + /* Transient lifecycle race with the page allocator. */ res = action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED); goto unlock_mutex; } -- 2.54.0
