Commit 5f0b48de authored by Ma Wupeng's avatar Ma Wupeng Committed by Wang Wensheng
Browse files

mm: Introduce fallback mechanism for memory reliable 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SK3S


CVE: NA

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

Introduce fallback mechanism for memory reliable. memory allocation will
fallback to non-mirrored region if zone's low watermark is reached and
kswapd will be awakened at this time.

This mechanism is enabled by defalut and can be disabled by adding
"reliable_debug=F" to the kernel parameters. This mechanism rely on
CONFIG_MEMORY_RELIABLE and need "kernelcore=reliable" in the kernel
parameters.

Signed-off-by: default avatarMa Wupeng <mawupeng1@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
parent 8968270e

Documentation/admin-guide/kernel-parameters.txt

+3 −1
Original line number Diff line number Diff line
@@ -4786,9 +4786,11 @@ 
			See Documentation/admin-guide/cgroup-v1/cpusets.rst.



	reliable_debug=	[ARM64]

			Format: [P]

			Format: [F][,P]

			Only works with CONFIG_MEMORY_RELIABLE and

			"kernelcore=reliable" is configured.

			F: User memory allocation(special user task, tmpfs) will

			not allocate memory from non-mirrored region if failed.

			P: Page cache does not use the reliable memory.



	reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory

include/linux/mem_reliable.h

+7 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ DECLARE_STATIC_KEY_FALSE(mem_reliable); 


extern bool reliable_enabled;

extern bool shmem_reliable;

extern bool reliable_allow_fallback;

extern bool pagecache_use_reliable_mem;

extern struct percpu_counter pagecache_reliable_pages;

extern struct percpu_counter anon_reliable_pages;
@@ -104,6 +105,11 @@ static inline bool mem_reliable_should_reclaim(void) 


	return false;

}



static inline bool reliable_allow_fb_enabled(void)

{

	return reliable_allow_fallback;

}

#else

#define reliable_enabled 0

#define pagecache_use_reliable_mem 0
@@ -138,6 +144,7 @@ static inline void mem_reliable_out_of_memory(gfp_t gfp_mask, 
					      unsigned int order,

					      int preferred_nid,

					      nodemask_t *nodemask) {}

static inline bool reliable_allow_fb_enabled(void) { return false; }

#endif



#endif

mm/mem_reliable.c

+5 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ EXPORT_SYMBOL_GPL(mem_reliable); 


bool reliable_enabled;

bool shmem_reliable __read_mostly = true;

bool reliable_allow_fallback __read_mostly = true;

bool pagecache_use_reliable_mem __read_mostly = true;

struct percpu_counter pagecache_reliable_pages;

struct percpu_counter anon_reliable_pages;
@@ -294,6 +295,10 @@ static int __init setup_reliable_debug(char *str) 
	 */

	for (; *str && *str != ','; str++) {

		switch (*str) {

		case 'F':

			reliable_allow_fallback = false;

			pr_info("disable memory reliable fallback\n");

			break;

		case 'P':

			pagecache_use_reliable_mem = false;

			pr_info("disable page cache use reliable memory\n");

mm/page_alloc.c

+25 −1
Original line number Diff line number Diff line
@@ -4668,6 +4668,28 @@ check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac) 
	return false;

}



#ifdef CONFIG_MEMORY_RELIABLE

static inline void mem_reliable_fallback_slowpath(gfp_t gfp_mask,

						  struct alloc_context *ac)

{

	if (!reliable_allow_fb_enabled())

		return;



	if (gfp_mask & __GFP_NOFAIL)

		return;



	if ((ac->highest_zoneidx == ZONE_NORMAL) && (gfp_mask & GFP_RELIABLE)) {

		ac->highest_zoneidx = gfp_zone(gfp_mask & ~GFP_RELIABLE);

		ac->preferred_zoneref = first_zones_zonelist(

			ac->zonelist, ac->highest_zoneidx, ac->nodemask);

		return;

	}

}

#else

static inline void mem_reliable_fallback_slowpath(gfp_t gfp_mask,

						  struct alloc_context *ac) {}

#endif



static inline struct page *

__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,

						struct alloc_context *ac)
@@ -4719,6 +4741,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
	if (alloc_flags & ALLOC_KSWAPD)

		wake_all_kswapds(order, gfp_mask, ac);



	mem_reliable_fallback_slowpath(gfp_mask, ac);



	/*

	 * The adjusted alloc_flags might result in immediate success, so try

	 * that first
@@ -5232,7 +5256,7 @@ static inline bool check_after_alloc(gfp_t *gfp, unsigned int order, 
	*_page = NULL;



out_retry:

	if (is_global_init(current)) {

	if (reliable_allow_fb_enabled() || is_global_init(current)) {

		*gfp &= ~GFP_RELIABLE;

		return true;

	}