mm: thp: replace folio_memcg() with folio_memcg_charged()

folio_memcg_charged() is intended for use when the user is unconcerned
about the returned memcg pointer. It is more efficient than folio_memcg().
Therefore, replace folio_memcg() with folio_memcg_charged().

Signed-off-by: Muchun Song <[email protected]>

Orabug: 37997580

From a correctness standpoint, this does not fix a bug but suppresses
the misleading warning:

  WARNING: CPU: 1 PID: 647 at include/linux/memcontrol.h:407 __folio_unqueue_deferred_split+0x1b8/0x1f0
  [...]
  Call Trace:
   <TASK>
   folios_put_refs+0xa9/0x390
   free_pages_and_swap_cache+0x1b4/0x1c0
   __tlb_batch_free_encoded_pages+0x45/0xc0
   tlb_finish_mmu+0x7d/0x190
   exit_mmap+0x1ba/0x4a0
   __mmput+0x4d/0x140
   exit_mm+0xd2/0x140
   do_exit+0x217/0x480
   do_group_exit+0x36/0xa0
   get_signal+0x94b/0x950
   arch_do_signal_or_restart+0x39/0x110
   syscall_exit_to_user_mode+0xd9/0x190
   do_syscall_64+0xca/0x1d0
   </TASK>

Link: https://lore.kernel.org/linux-mm/[email protected]/
Reviewed-by: Imran Khan <[email protected]>
Signed-off-by: Harry Yoo <[email protected]>

Author: Muchun Song

mm/huge_memory.c

@@ -3722,7 +3722,7 @@ bool __folio_unqueue_deferred_split(struct folio *folio)
 	bool unqueued = false;
 
 	WARN_ON_ONCE(folio_ref_count(folio));
-	WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg(folio));
+	WARN_ON_ONCE(!mem_cgroup_disabled() && !folio_memcg_charged(folio));
 
 	ds_queue = folio_split_queue_lock_irqsave(folio, &flags);
 	if (!list_empty(&folio->_deferred_list)) {