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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: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vladimir Davydov 2014-12-12 16:55:15 -08:00 committed by Linus Torvalds
parent 4e701d7b37
commit 6f185c290e
2 changed files with 7 additions and 35 deletions
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7
include/linux/sched.h
View File

@ -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;

35
mm/memcontrol.c
View File

@ -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)