From b0f205c2a3082dd9081f9a94e50658c5fa906ff1 Mon Sep 17 00:00:00 2001 From: Eric B Munson Date: Thu, 5 Nov 2015 18:51:39 -0800 Subject: mm: mlock: add mlock flags to enable VM_LOCKONFAULT usage The previous patch introduced a flag that specified pages in a VMA should be placed on the unevictable LRU, but they should not be made present when the area is created. This patch adds the ability to set this state via the new mlock system calls. We add MLOCK_ONFAULT for mlock2 and MCL_ONFAULT for mlockall. MLOCK_ONFAULT will set the VM_LOCKONFAULT modifier for VM_LOCKED. MCL_ONFAULT should be used as a modifier to the two other mlockall flags. When used with MCL_CURRENT, all current mappings will be marked with VM_LOCKED | VM_LOCKONFAULT. When used with MCL_FUTURE, the mm->def_flags will be marked with VM_LOCKED | VM_LOCKONFAULT. When used with both MCL_CURRENT and MCL_FUTURE, all current mappings and mm->def_flags will be marked with VM_LOCKED | VM_LOCKONFAULT. Prior to this patch, mlockall() will unconditionally clear the mm->def_flags any time it is called without MCL_FUTURE. This behavior is maintained after adding MCL_ONFAULT. If a call to mlockall(MCL_FUTURE) is followed by mlockall(MCL_CURRENT), the mm->def_flags will be cleared and new VMAs will be unlocked. This remains true with or without MCL_ONFAULT in either mlockall() invocation. munlock() will unconditionally clear both vma flags. munlockall() unconditionally clears for VMA flags on all VMAs and in the mm->def_flags field. Signed-off-by: Eric B Munson Acked-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Jonathan Corbet Cc: Catalin Marinas Cc: Geert Uytterhoeven Cc: Guenter Roeck Cc: Heiko Carstens Cc: Kirill A. Shutemov Cc: Michael Kerrisk Cc: Ralf Baechle Cc: Shuah Khan Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/uapi/asm-generic/mman-common.h | 5 +++++ include/uapi/asm-generic/mman.h | 1 + 2 files changed, 6 insertions(+) (limited to 'include/uapi') diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h index ddc3b36f1046..a74dd84bbb6d 100644 --- a/include/uapi/asm-generic/mman-common.h +++ b/include/uapi/asm-generic/mman-common.h @@ -25,6 +25,11 @@ # define MAP_UNINITIALIZED 0x0 /* Don't support this flag */ #endif +/* + * Flags for mlock + */ +#define MLOCK_ONFAULT 0x01 /* Lock pages in range after they are faulted in, do not prefault */ + #define MS_ASYNC 1 /* sync memory asynchronously */ #define MS_INVALIDATE 2 /* invalidate the caches */ #define MS_SYNC 4 /* synchronous memory sync */ diff --git a/include/uapi/asm-generic/mman.h b/include/uapi/asm-generic/mman.h index e9fe6fd2a074..7162cd4cca73 100644 --- a/include/uapi/asm-generic/mman.h +++ b/include/uapi/asm-generic/mman.h @@ -17,5 +17,6 @@ #define MCL_CURRENT 1 /* lock all current mappings */ #define MCL_FUTURE 2 /* lock all future mappings */ +#define MCL_ONFAULT 4 /* lock all pages that are faulted in */ #endif /* __ASM_GENERIC_MMAN_H */ -- cgit v1.2.3