gfp: add __GFP_NOACCOUNT (8f4fc071) · Commits · 戴 / test

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. Note, since in case of kmemleak enabled each kmalloc implies yet another allocation from the kmemleak_object cache, we add __GFP_NOACCOUNT to gfp_kmemleak_mask. Alternatively, we could introduce a per kmem cache flag disabling accounting for all allocations of a particular kind, but (a) we would not be able to bypass accounting for kmalloc then and (b) a kmem cache with this flag set could not be merged with a kmem cache without this flag, which would increase the number of global caches and therefore fragmentation even if the memory cgroup controller is not used. Despite its generic name, currently __GFP_NOACCOUNT disables accounting only for kmem allocations while user page allocations are always charged. To catch abusing of this flag, a warning is issued on an attempt of passing it to mem_cgroup_try_charge. Signed-off-by:

Vladimir Davydov <vdavydov@parallels.com> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Greg Thelen <gthelen@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: <stable@vger.kernel.org> [4.0.x] Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/gfp.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -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
		@@ -87,6 +88,7 @@ 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)

include/linux/memcontrol.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -463,6 +463,8 @@ memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
		if (!memcg_kmem_enabled())
		return true;

		if (gfp & __GFP_NOACCOUNT)
		return true;
		/*
		* __GFP_NOFAIL allocations will move on even if charging is not
		* possible. Therefore we don't even try, and have this allocation
		@@ -522,6 +524,8 @@ memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
		{
		if (!memcg_kmem_enabled())
		return cachep;
		if (gfp & __GFP_NOACCOUNT)
		return cachep;
		if (gfp & __GFP_NOFAIL)
		return cachep;
		if (in_interrupt() \|\| (!current->mm) \|\| (current->flags & PF_KTHREAD))

mm/kmemleak.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -115,7 +115,8 @@
		#define BYTES_PER_POINTER sizeof(void *)

		/* GFP bitmask for kmemleak internal allocations */
		#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL \| GFP_ATOMIC)) \| \
		#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL \| GFP_ATOMIC \| \
		__GFP_NOACCOUNT)) \| \
		__GFP_NORETRY \| __GFP_NOMEMALLOC \| \
		__GFP_NOWARN)

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