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Commit 6f185c29 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

memcg: turn memcg_kmem_skip_account into a bit field 



It isn't supposed to stack, so turn it into a bit-field to save 4 bytes on
the task_struct.

Also, remove the memcg_stop/resume_kmem_account helpers - it is clearer to
set/clear the flag inline.  Regarding the overwhelming comment to the
helpers, which is removed by this patch too, we already have a compact yet
accurate explanation in memcg_schedule_cache_create, no need in yet
another one.

Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4e701d7b

include/linux/sched.h

+5 −2
Original line number Diff line number Diff line
@@ -1364,6 +1364,10 @@ struct task_struct { 
	unsigned sched_reset_on_fork:1;

	unsigned sched_contributes_to_load:1;



#ifdef CONFIG_MEMCG_KMEM

	unsigned memcg_kmem_skip_account:1;

#endif



	unsigned long atomic_flags; /* Flags needing atomic access. */



	pid_t pid;
@@ -1679,8 +1683,7 @@ struct task_struct { 
	/* bitmask and counter of trace recursion */

	unsigned long trace_recursion;

#endif /* CONFIG_TRACING */

#ifdef CONFIG_MEMCG /* memcg uses this to do batch job */

	unsigned int memcg_kmem_skip_account;

#ifdef CONFIG_MEMCG

	struct memcg_oom_info {

		struct mem_cgroup *memcg;

		gfp_t gfp_mask;

mm/memcontrol.c

+2 −33
Original line number Diff line number Diff line
@@ -2673,37 +2673,6 @@ static void memcg_unregister_cache(struct kmem_cache *cachep) 
	css_put(&memcg->css);

}



/*

 * During the creation a new cache, we need to disable our accounting mechanism

 * altogether. This is true even if we are not creating, but rather just

 * enqueing new caches to be created.

 *

 * This is because that process will trigger allocations; some visible, like

 * explicit kmallocs to auxiliary data structures, name strings and internal

 * cache structures; some well concealed, like INIT_WORK() that can allocate

 * objects during debug.

 *

 * If any allocation happens during memcg_kmem_get_cache, we will recurse back

 * to it. This may not be a bounded recursion: since the first cache creation

 * failed to complete (waiting on the allocation), we'll just try to create the

 * cache again, failing at the same point.

 *

 * memcg_kmem_get_cache is prepared to abort after seeing a positive count of

 * memcg_kmem_skip_account. So we enclose anything that might allocate memory

 * inside the following two functions.

 */

static inline void memcg_stop_kmem_account(void)

{

	VM_BUG_ON(!current->mm);

	current->memcg_kmem_skip_account++;

}



static inline void memcg_resume_kmem_account(void)

{

	VM_BUG_ON(!current->mm);

	current->memcg_kmem_skip_account--;

}



int __memcg_cleanup_cache_params(struct kmem_cache *s)

{

	struct kmem_cache *c;
@@ -2798,9 +2767,9 @@ static void memcg_schedule_register_cache(struct mem_cgroup *memcg, 
	 * this point we can't allow ourselves back into memcg_kmem_get_cache,

	 * the safest choice is to do it like this, wrapping the whole function.

	 */

	memcg_stop_kmem_account();

	current->memcg_kmem_skip_account = 1;

	__memcg_schedule_register_cache(memcg, cachep);

	memcg_resume_kmem_account();

	current->memcg_kmem_skip_account = 0;

}



int __memcg_charge_slab(struct kmem_cache *cachep, gfp_t gfp, int order)