mm: correctly charge compressed memory to its memcg

commit cd08d80 upstream.

Kswapd will reclaim memory when memory pressure is high, the annonymous
memory will be compressed and stored in the zpool if zswap is enabled.
The memcg_kmem_bypass() in get_obj_cgroup_from_page() will bypass the
kernel thread and cause the compressed memory not be charged to its memory
cgroup.

Remove the memcg_kmem_bypass() call and properly charge compressed memory
to its corresponding memory cgroup.

Link: https://lore.kernel.org/linux-mm/CALvZod4nnn8BHYqAM4xtcR0Ddo2-Wr8uKm9h_CHWUaXw7g_DCg@mail.gmail.com/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: f4840cc ("zswap: memcg accounting")
Signed-off-by: Li Liguang <[email protected]>
Signed-off-by: Johannes Weiner <[email protected]>
Acked-by: Shakeel Butt <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: <[email protected]>	[5.19+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Li Liguang

mm/memcontrol.c

@@ -2971,7 +2971,7 @@ struct obj_cgroup *get_obj_cgroup_from_page(struct page *page)
 {
 	struct obj_cgroup *objcg;
 
-	if (!memcg_kmem_enabled() || memcg_kmem_bypass())
+	if (!memcg_kmem_enabled())
 		return NULL;
 
 	if (PageMemcgKmem(page)) {