[Devel] [PATCH rh7 1/2] gfp: add __GFP_NOACCOUNT

[Vladimir Davydov]

Not all kmem allocations should be accounted to memcg. The following
patch gives an example when accounting of a certain type of allocations
to memcg can effectively result in a memory leak. This patch adds the
__GFP_NOACCOUNT flag which if passed to kmalloc and friends will force
the allocation to go through the root cgroup. It will be used by the
next patch.

Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 include/linux/gfp.h        |    2 ++
 include/linux/memcontrol.h |    4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 4d66a5daf0bf..b26f7f11d394 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -30,6 +30,7 @@ struct vm_area_struct;
 #define ___GFP_HARDWALL		0x20000u
 #define ___GFP_THISNODE		0x40000u
 #define ___GFP_RECLAIMABLE	0x80000u
+#define ___GFP_NOACCOUNT	0x100000u
 #define ___GFP_NOTRACK		0x200000u
 #define ___GFP_NO_KSWAPD	0x400000u
 #define ___GFP_OTHER_NODE	0x800000u
@@ -85,6 +86,7 @@ struct vm_area_struct;
 #define __GFP_HARDWALL   ((__force gfp_t)___GFP_HARDWALL) /* Enforce hardwall cpuset memory allocs */
 #define __GFP_THISNODE	((__force gfp_t)___GFP_THISNODE)/* No fallback, no policies */
 #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) /* Page is reclaimable */
+#define __GFP_NOACCOUNT	((__force gfp_t)___GFP_NOACCOUNT) /* Don't account to kmemcg */
 #define __GFP_NOTRACK	((__force gfp_t)___GFP_NOTRACK)  /* Don't track with kmemcheck */
 
 #define __GFP_NO_KSWAPD	((__force gfp_t)___GFP_NO_KSWAPD)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 91feab1605a8..77577b8c6cd6 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -496,7 +496,7 @@ memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
 	 * res_counter_charge_nofail, but we hope those allocations are rare,
 	 * and won't be worth the trouble.
 	 */
-	if (gfp & __GFP_NOFAIL)
+	if (gfp & (__GFP_NOFAIL|__GFP_NOACCOUNT))
 		return true;
 	if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
 		return true;
@@ -552,7 +552,7 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
 {
 	if (!memcg_kmem_enabled())
 		return cachep;
-	if (gfp & __GFP_NOFAIL)
+	if (gfp & (__GFP_NOFAIL|__GFP_NOACCOUNT))
 		return cachep;
 	if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
 		return cachep;
-- 
1.7.10.4