From 6f185c290edec576a2cccd6670e5b8e02e6f04db Mon Sep 17 00:00:00 2001 From: Vladimir Davydov Date: Fri, 12 Dec 2014 16:55:15 -0800 Subject: [PATCH] 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 Cc: Johannes Weiner Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 7 +++++-- mm/memcontrol.c | 35 ++--------------------------------- 2 files changed, 7 insertions(+), 35 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 55f5ee7cc3d3..4cfdbcf8cf56 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -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; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index d9fab72da52e..11cbfde4dc6d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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) -- GitLab