[merged mm-stable] mm-sparse-remove-warn_ons-from-onlineoffline_mem_sections.patch removed from -mm tree

[merged mm-stable] mm-sparse-remove-warn_ons-from-onlineoffline_mem_sections.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/sparse: remove WARN_ONs from (online|offline)_mem_sections()
has been removed from the -mm tree.  Its filename was
     mm-sparse-remove-warn_ons-from-onlineoffline_mem_sections.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: "David Hildenbrand (Arm)" <david@kernel.org>
Subject: mm/sparse: remove WARN_ONs from (online|offline)_mem_sections()
Date: Fri, 20 Mar 2026 23:13:35 +0100

We do not allow offlining of memory with memory holes, and always hotplug
memory without holes.

Consequently, we cannot end up onlining or offlining memory sections that
have holes (including invalid sections).  That's also why these WARN_ONs
never fired.

Let's remove the WARN_ONs along with the TODO regarding double-checking.
Link: https://lkml.kernel.org/r/20260320-sparsemem_cleanups-v2-3-096addc8800d@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/sparse.c |   17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

--- a/mm/sparse.c~mm-sparse-remove-warn_ons-from-onlineoffline_mem_sections
+++ a/mm/sparse.c
@@ -638,13 +638,8 @@ void online_mem_sections(unsigned long s
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		unsigned long section_nr = pfn_to_section_nr(pfn);
-		struct mem_section *ms;
+		struct mem_section *ms = __nr_to_section(section_nr);
 
-		/* onlining code should never touch invalid ranges */
-		if (WARN_ON(!valid_section_nr(section_nr)))
-			continue;
-
-		ms = __nr_to_section(section_nr);
 		ms->section_mem_map |= SECTION_IS_ONLINE;
 	}
 }
@@ -656,16 +651,8 @@ void offline_mem_sections(unsigned long
 
 	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
 		unsigned long section_nr = pfn_to_section_nr(pfn);
-		struct mem_section *ms;
-
-		/*
-		 * TODO this needs some double checking. Offlining code makes
-		 * sure to check pfn_valid but those checks might be just bogus
-		 */
-		if (WARN_ON(!valid_section_nr(section_nr)))
-			continue;
+		struct mem_section *ms = __nr_to_section(section_nr);
 
-		ms = __nr_to_section(section_nr);
 		ms->section_mem_map &= ~SECTION_IS_ONLINE;
 	}
 }
_

Patches currently in -mm which might be from david@kernel.org are