Re: [PATCH v6 2/4] mm/memory-failure: classify get_any_page() failures by reason

[Breno Leitao <leitao@debian.org>]

On Tue, May 12, 2026 at 10:21:50AM +0200, David Hildenbrand (Arm) wrote:
> 
> >  		}
> >  		goto unlock_mutex;
> >  	} else if (res < 0) {
> > -		if (is_reserved)
> > +		/*
> > +		 * Promote a stable unhandlable kernel page diagnosed by
> > +		 * get_hwpoison_page() to MF_MSG_KERNEL alongside reserved
> > +		 * pages; transient lifecycle races stay as MF_MSG_GET_HWPOISON.
> > +		 */
> > +		if (is_reserved || gp_status == MF_GET_PAGE_UNHANDLABLE)
> >  			res = action_result(pfn, MF_MSG_KERNEL, MF_IGNORED);
> 
> 
> It's all a bit of a mess. get_hwpoison_page() should just indicate that a page
> is unhandable if it is PG_reserved?

Are you saying that we should identify if the page is PG_reserved in
get_hwpoison_page() instead of in memory_failure(), as done in the
previous patch ("mm/memory-failure: report MF_MSG_KERNEL for reserved
pages") ?

> Why can't we just return a special error code from  get_hwpoison_page()? We ahve
> plenty of errno values to chose from.

Something like:


diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 866c4428ac7ef..0a6d83575833e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -878,7 +878,7 @@ static const char *action_name[] = {
 };
 
 static const char * const action_page_types[] = {
-	[MF_MSG_KERNEL]			= "reserved kernel page",
+	[MF_MSG_KERNEL]			= "unrecoverable kernel page",
 	[MF_MSG_KERNEL_HIGH_ORDER]	= "high-order kernel page",
 	[MF_MSG_HUGE]			= "huge page",
 	[MF_MSG_FREE_HUGE]		= "free huge page",
@@ -1394,6 +1394,21 @@ static int get_any_page(struct page *p, unsigned long flags)
 	int ret = 0, pass = 0;
 	bool count_increased = false;

+	if (PageReserved(p)) {
+		ret = -ENOTRECOVERABLE;
+		goto out;
+	}
+
 	if (flags & MF_COUNT_INCREASED)
 		count_increased = true;
 
@@ -1422,7 +1437,7 @@ static int get_any_page(struct page *p, unsigned long flags)
 				shake_page(p);
 				goto try_again;
 			}
-			ret = -EIO;
+			ret = -ENOTRECOVERABLE;
 			goto out;
 		}
 	}
@@ -1441,10 +1456,10 @@ static int get_any_page(struct page *p, unsigned long flags)
 			goto try_again;
 		}
 		put_page(p);
-		ret = -EIO;
+		ret = -ENOTRECOVERABLE;
 	}
 out:
-	if (ret == -EIO)
+	if (ret == -EIO || ret == -ENOTRECOVERABLE)
 		pr_err("%#lx: unhandlable page.\n", page_to_pfn(p));
 
 	return ret;
@@ -2431,6 +2448,9 @@ 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 == -ENOTRECOVERABLE) {
+		res = action_result(pfn, MF_MSG_KERNEL, MF_IGNORED);
+		goto unlock_mutex;
 	} else if (res < 0) {
 		res = action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED);
 		goto unlock_mutex;


If that is what you are suggestion, maybe we can create another
MF_MSG_RESERVED? and another return value for get_any_page() to track
the reserve pages ?

Thanks for the review and suggestions,
--breno