mm: Introduce reliable_debug=S to control shmem use mirrored memory

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

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

Introduce reliable_debug=S to control shmem use mirrored memory.
Signed-off-by: NMa Wupeng <mawupeng1@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>

Documentation/admin-guide/kernel-parameters.txt

@@ -4778,11 +4778,12 @@
 			See Documentation/admin-guide/cgroup-v1/cpusets.rst.
 
 	reliable_debug=	[ARM64]
-			Format: [F][,P]
+			Format: [F][,S][,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.
+			S: The shmem does not use the reliable memory.
 			P: Page cache does not use the reliable memory.
 
 	reserve=	[KNL,BUGS] Force kernel to ignore I/O ports or memory

mm/mem_reliable.c

@@ -342,6 +342,10 @@ static int __init setup_reliable_debug(char *str)
 			reliable_allow_fallback = false;
 			pr_info("disable memory reliable fallback\n");
 			break;
+		case 'S':
+			shmem_reliable = false;
+			pr_info("disable shmem use reliable memory\n");
+			break;
 		case 'P':
 			pagecache_use_reliable_mem = false;
 			pr_info("disable page cache use reliable memory\n");