mm/page_alloc: dedupe some memcg uncharging logic

The duplication makes it seem like some work is required before uncharging
in the !PageHWPoison case.  But it isn't, so we can simplify the code a
little.

Note the PageMemcgKmem check is redundant, but I've left it in as it
avoids an unnecessary function call.

Link: https://lkml.kernel.org/r/20231108164920.3401565-1-jackmanb@google.comSigned-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/page_alloc.c

@@ -1086,13 +1086,11 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	trace_mm_page_free(page, order);
 	kmsan_free_page(page, order);
 
+	if (memcg_kmem_online() && PageMemcgKmem(page))
+		__memcg_kmem_uncharge_page(page, order);
+
 	if (unlikely(PageHWPoison(page)) && !order) {
-		/*
-		 * Do not let hwpoison pages hit pcplists/buddy
-		 * Untie memcg state and reset page's owner
-		 */
-		if (memcg_kmem_online() && PageMemcgKmem(page))
-			__memcg_kmem_uncharge_page(page, order);
+		/* Do not let hwpoison pages hit pcplists/buddy */
 		reset_page_owner(page, order);
 		page_table_check_free(page, order);
 		return false;
@@ -1123,8 +1121,6 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	}
 	if (PageMappingFlags(page))
 		page->mapping = NULL;
-	if (memcg_kmem_online() && PageMemcgKmem(page))
-		__memcg_kmem_uncharge_page(page, order);
 	if (is_check_pages_enabled()) {
 		if (free_page_is_bad(page))
 			bad++;