Subject: linux-next: manual merge of the akpm-current tree with the slab tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 3 Dec 2021 18:19:51 +1100

Hi all,

Today's linux-next merge of the akpm-current tree got a conflict in:

  mm/memcontrol.c

between commit:

  eefa12e18a92 ("mm/memcg: Convert slab objcgs from struct page to struct slab")

from the slab tree and commit:

  93e959c235eb ("mm/memcg: relocate mod_objcg_mlstate(), get_obj_stock() and put_obj_stock()")

from the akpm-current tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc mm/memcontrol.c
index 522fff11d6d1,69d4fdafbb80..000000000000
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@@ -2816,10 -2769,63 +2769,63 @@@ retry
   */
  #define OBJCGS_CLEAR_MASK	(__GFP_DMA | __GFP_RECLAIMABLE | __GFP_ACCOUNT)
  
+ /*
+  * Most kmem_cache_alloc() calls are from user context. The irq disable/enable
+  * sequence used in this case to access content from object stock is slow.
+  * To optimize for user context access, there are now two object stocks for
+  * task context and interrupt context access respectively.
+  *
+  * The task context object stock can be accessed by disabling preemption only
+  * which is cheap in non-preempt kernel. The interrupt context object stock
+  * can only be accessed after disabling interrupt. User context code can
+  * access interrupt object stock, but not vice versa.
+  */
+ static inline struct obj_stock *get_obj_stock(unsigned long *pflags)
+ {
+ 	struct memcg_stock_pcp *stock;
+ 
+ 	if (likely(in_task())) {
+ 		*pflags = 0UL;
+ 		preempt_disable();
+ 		stock = this_cpu_ptr(&memcg_stock);
+ 		return &stock->task_obj;
+ 	}
+ 
+ 	local_irq_save(*pflags);
+ 	stock = this_cpu_ptr(&memcg_stock);
+ 	return &stock->irq_obj;
+ }
+ 
+ static inline void put_obj_stock(unsigned long flags)
+ {
+ 	if (likely(in_task()))
+ 		preempt_enable();
+ 	else
+ 		local_irq_restore(flags);
+ }
+ 
+ /*
+  * mod_objcg_mlstate() may be called with irq enabled, so
+  * mod_memcg_lruvec_state() should be used.
+  */
+ static inline void mod_objcg_mlstate(struct obj_cgroup *objcg,
+ 				     struct pglist_data *pgdat,
+ 				     enum node_stat_item idx, int nr)
+ {
+ 	struct mem_cgroup *memcg;
+ 	struct lruvec *lruvec;
+ 
+ 	rcu_read_lock();
+ 	memcg = obj_cgroup_memcg(objcg);
+ 	lruvec = mem_cgroup_lruvec(memcg, pgdat);
+ 	mod_memcg_lruvec_state(lruvec, idx, nr);
+ 	rcu_read_unlock();
+ }
+ 
 -int memcg_alloc_page_obj_cgroups(struct page *page, struct kmem_cache *s,
 -				 gfp_t gfp, bool new_page)
 +int memcg_alloc_slab_cgroups(struct slab *slab, struct kmem_cache *s,
 +				 gfp_t gfp, bool new_slab)
  {
 -	unsigned int objects = objs_per_slab_page(s, page);
 +	unsigned int objects = objs_per_slab(s, slab);
  	unsigned long memcg_data;
  	void *vec;