Messages in this thread | | | Date | Wed, 18 Apr 2012 11:18:06 -0700 | Subject | Re: [RFC][PATCH 2/6] memcg: add pc_set_mem_cgroup_and_flags() | From | Ying Han <> |
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On Wed, Apr 18, 2012 at 12:23 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > (2012/04/18 6:17), Ying Han wrote: > >> On Wed, Mar 28, 2012 at 3:51 AM, KAMEZAWA Hiroyuki >> <kamezawa.hiroyu@jp.fujitsu.com> wrote: >>> Consolidate a code for setting pc->mem_cgroup and USED bit which requires smp_wmb(). >>> And remove a macro PCGF_NOCOPY_AT_SPLIT which isn't helpful to read code, now. >>> >>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >>> --- >>> include/linux/page_cgroup.h | 18 ++++++++++++++++++ >>> mm/memcontrol.c | 18 ++++-------------- >>> 2 files changed, 22 insertions(+), 14 deletions(-) >>> >>> diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h >>> index 92768cb..2707809 100644 >>> --- a/include/linux/page_cgroup.h >>> +++ b/include/linux/page_cgroup.h >>> @@ -1,6 +1,8 @@ >>> #ifndef __LINUX_PAGE_CGROUP_H >>> #define __LINUX_PAGE_CGROUP_H >>> >>> +#include <linux/smp.h> >>> + >>> enum { >>> /* flags for mem_cgroup */ >>> PCG_LOCK, /* Lock for pc->mem_cgroup and following bits. */ >>> @@ -94,6 +96,22 @@ pc_set_mem_cgroup(struct page_cgroup *pc, struct mem_cgroup *memcg) >>> pc->mem_cgroup = memcg; >>> } >>> >>> +static inline void >>> +pc_set_mem_cgroup_and_flags(struct page_cgroup *pc, struct mem_cgroup *memcg, >>> + unsigned long flags) >>> +{ >>> + pc->mem_cgroup = memcg; >>> + /* >>> + * We access a page_cgroup asynchronously without lock_page_cgroup(). >>> + * Especially when a page_cgroup is taken from a page, pc's mem_cgroup >>> + * is accessed after testing USED bit. To make pc's mem_cgroup visible >>> + * before USED bit, we need memory barrier here. >>> + * See mem_cgroup_add_lru_list(), etc. >>> + */ >>> + smp_wmb(); >>> + pc->flags = flags; >>> +} >>> + >>> #else /* CONFIG_CGROUP_MEM_RES_CTLR */ >>> struct page_cgroup; >>> >>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>> index 8077460..d366b60 100644 >>> --- a/mm/memcontrol.c >>> +++ b/mm/memcontrol.c >>> @@ -2511,16 +2511,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg, >>> } >>> } >>> >>> - pc_set_mem_cgroup(pc, memcg); >>> - /* >>> - * We access a page_cgroup asynchronously without lock_page_cgroup(). >>> - * Especially when a page_cgroup is taken from a page, pc's mem_cgroup >>> - * is accessed after testing USED bit. To make pc's mem_cgroup visible >>> - * before USED bit, we need memory barrier here. >>> - * See mem_cgroup_add_lru_list(), etc. >>> - */ >>> - smp_wmb(); >>> - SetPageCgroupUsed(pc); >> >> I might be confused. We removed this SetPageCgroupUsed() but not >> adding it back elsewhere ? >> >> --Ying >> >>> + pc_set_mem_cgroup_and_flags(pc, memcg, BIT(PCG_USED) | BIT(PCG_LOCK)); > > > Added here. This sets > > | memcg pointer | Used | Locked |
Ah. I missed that part.
Thanks
--Ying
> > > Thanks, > -Kame > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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