Commit bfc245bc authored by Roman Gushchin's avatar Roman Gushchin Committed by Zheng Zengkai
Browse files

mm: Introduce page memcg flags 

mainline inclusion
from mainline-v5.11-rc1
commit 87944e29
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4C0GB
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=87944e2992bd28098c6806086a1e96bb4d0e502b



----------------------------------------------------------------------

The lowest bit in page->memcg_data is used to distinguish between struct
memory_cgroup pointer and a pointer to a objcgs array.  All checks and
modifications of this bit are open-coded.

Let's formalize it using page memcg flags, defined in enum
page_memcg_data_flags.

Additional flags might be added later.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Link: https://lkml.kernel.org/r/20201027001657.3398190-4-guro@fb.com
Link: https://lore.kernel.org/bpf/20201201215900.3569844-4-guro@fb.com


Signed-off-by: default avatarChen Huang <chenhuang5@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: default avatarChen Wandun <chenwandun@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent dbaf3609

include/linux/memcontrol.h

+20 −12
Original line number Diff line number Diff line
@@ -373,6 +373,15 @@ extern int sysctl_memcg_qos_handler(struct ctl_table *table, 


extern struct mem_cgroup *root_mem_cgroup;



enum page_memcg_data_flags {

	/* page->memcg_data is a pointer to an objcgs vector */

	MEMCG_DATA_OBJCGS = (1UL << 0),

	/* the next bit after the last actual flag */

	__NR_MEMCG_DATA_FLAGS  = (1UL << 1),

};



#define MEMCG_DATA_FLAGS_MASK (__NR_MEMCG_DATA_FLAGS - 1)



/*

 * page_memcg - get the memory cgroup associated with a page

 * @page: a pointer to the page struct
@@ -434,13 +443,7 @@ static inline struct mem_cgroup *page_memcg_check(struct page *page) 
	 */

	unsigned long memcg_data = READ_ONCE(page->memcg_data);



	/*

	 * The lowest bit set means that memcg isn't a valid

	 * memcg pointer, but a obj_cgroups pointer.

	 * In this case the page is shared and doesn't belong

	 * to any specific memory cgroup.

	 */

	if (memcg_data & 0x1UL)

	if (memcg_data & MEMCG_DATA_OBJCGS)

		return NULL;



	return (struct mem_cgroup *)memcg_data;
@@ -459,7 +462,11 @@ static inline struct mem_cgroup *page_memcg_check(struct page *page) 
 */

static inline struct obj_cgroup **page_objcgs(struct page *page)

{

	return (struct obj_cgroup **)(READ_ONCE(page->memcg_data) & ~0x1UL);

	unsigned long memcg_data = READ_ONCE(page->memcg_data);



	VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS), page);



	return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);

}



/*
@@ -474,10 +481,10 @@ static inline struct obj_cgroup **page_objcgs_check(struct page *page) 
{

	unsigned long memcg_data = READ_ONCE(page->memcg_data);



	if (memcg_data && (memcg_data & 0x1UL))

		return (struct obj_cgroup **)(memcg_data & ~0x1UL);



	if (!memcg_data || !(memcg_data & MEMCG_DATA_OBJCGS))

		return NULL;



	return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);

}



/*
@@ -490,7 +497,8 @@ static inline struct obj_cgroup **page_objcgs_check(struct page *page) 
static inline bool set_page_objcgs(struct page *page,

					struct obj_cgroup **objcgs)

{

	return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL);

	return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs |

			MEMCG_DATA_OBJCGS);

}

#else

static inline struct obj_cgroup **page_objcgs(struct page *page)