+ mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/page_owner: hoist CONFIG_MEMCG to function level for print_page_owner_memcg()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ye Liu <ye.liu@linux.dev>
Subject: mm/page_owner: hoist CONFIG_MEMCG to function level for print_page_owner_memcg()
Date: Tue, 30 Jun 2026 09:53:21 +0800

print_page_owner_memcg() has CONFIG_MEMCG guarding its entire body via
#ifdef inside the function, which leaves a no-op { return ret; } when the
config is disabled.  Hoist the #ifdef to the top level so the real
implementation and the empty stub are two clearly separated definitions.

No functional change.

Link: https://lore.kernel.org/20260630015331.147174-5-ye.liu@linux.dev
Signed-off-by: Ye Liu <ye.liu@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/page_owner.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/mm/page_owner.c~mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg
+++ a/mm/page_owner.c
@@ -522,13 +522,13 @@ ext_put_continue:
 	seq_putc(m, '\n');
 }
 
+#ifdef CONFIG_MEMCG
 /*
  * Looking for memcg information and print it out
  */
 static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
 					 struct page *page)
 {
-#ifdef CONFIG_MEMCG
 	unsigned long memcg_data;
 	struct mem_cgroup *memcg;
 	bool online;
@@ -556,10 +556,16 @@ static inline int print_page_owner_memcg
 			name);
 out_unlock:
 	rcu_read_unlock();
-#endif /* CONFIG_MEMCG */
 
 	return ret;
 }
+#else
+static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
+					 struct page *page)
+{
+	return ret;
+}
+#endif
 
 static ssize_t
 print_page_owner(char __user *buf, size_t count, unsigned long pfn,
_

Patches currently in -mm which might be from ye.liu@linux.dev are

mm-page_owner-extract-skip_buddy_pages-helper-to-unify-buddy-page-skipping.patch
mm-page_owner-add-mr_never-to-enum-migrate_reason-and-use-it-for-last_migrate_reason.patch
mm-use-enum-migrate_reason-instead-of-int-for-migration-reason-parameters.patch
mm-page_owner-hoist-config_memcg-to-function-level-for-print_page_owner_memcg.patch
mm-page_owner-add-missing-newline-to-count_threshold-format-string.patch
mm-page_owner-move-free_ts_nsec-output-to-free-section-in-__dump_page_owner.patch
mm-page_owner-drop-redundant-page_owner-prefix-from-static-symbols.patch
mm-page_owner-clamp-skip_buddy_pages-pfn-advance-at-max_order_nr_pages-boundary.patch
mm-page_owner-use-memcg_data-snapshot-instead-of-pagememcgkmem-to-avoid-toctou-vm_bug_on.patch