From de60f5f10c58d4f34b68622442c0e04180367f3f Mon Sep 17 00:00:00 2001 From: Eric B Munson Date: Thu, 5 Nov 2015 18:51:36 -0800 Subject: mm: introduce VM_LOCKONFAULT The cost of faulting in all memory to be locked can be very high when working with large mappings. If only portions of the mapping will be used this can incur a high penalty for locking. For the example of a large file, this is the usage pattern for a large statical language model (probably applies to other statical or graphical models as well). For the security example, any application transacting in data that cannot be swapped out (credit card data, medical records, etc). This patch introduces the ability to request that pages are not pre-faulted, but are placed on the unevictable LRU when they are finally faulted in. The VM_LOCKONFAULT flag will be used together with VM_LOCKED and has no effect when set without VM_LOCKED. Setting the VM_LOCKONFAULT flag for a VMA will cause pages faulted into that VMA to be added to the unevictable LRU when they are faulted or if they are already present, but will not cause any missing pages to be faulted in. Exposing this new lock state means that we cannot overload the meaning of the FOLL_POPULATE flag any longer. Prior to this patch it was used to mean that the VMA for a fault was locked. This means we need the new FOLL_MLOCK flag to communicate the locked state of a VMA. FOLL_POPULATE will now only control if the VMA should be populated and in the case of VM_LOCKONFAULT, it will not be set. Signed-off-by: Eric B Munson Acked-by: Kirill A. Shutemov Acked-by: Vlastimil Babka Cc: Michal Hocko Cc: Jonathan Corbet Cc: Catalin Marinas Cc: Geert Uytterhoeven Cc: Guenter Roeck Cc: Heiko Carstens Cc: Michael Kerrisk Cc: Ralf Baechle Cc: Shuah Khan Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include') diff --git a/include/linux/mm.h b/include/linux/mm.h index 3c258f8eb9ae..906c46a05707 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -139,6 +139,7 @@ extern unsigned int kobjsize(const void *objp); #define VM_DONTCOPY 0x00020000 /* Do not copy this vma on fork */ #define VM_DONTEXPAND 0x00040000 /* Cannot expand with mremap() */ +#define VM_LOCKONFAULT 0x00080000 /* Lock the pages covered when they are faulted in */ #define VM_ACCOUNT 0x00100000 /* Is a VM accounted object */ #define VM_NORESERVE 0x00200000 /* should the VM suppress accounting */ #define VM_HUGETLB 0x00400000 /* Huge TLB Page VM */ @@ -202,6 +203,9 @@ extern unsigned int kobjsize(const void *objp); /* This mask defines which mm->def_flags a process can inherit its parent */ #define VM_INIT_DEF_MASK VM_NOHUGEPAGE +/* This mask is used to clear all the VMA flags used by mlock */ +#define VM_LOCKED_CLEAR_MASK (~(VM_LOCKED | VM_LOCKONFAULT)) + /* * mapping from the currently active vm_flags protection bits (the * low four bits) to a page protection mask.. @@ -2137,6 +2141,7 @@ static inline struct page *follow_page(struct vm_area_struct *vma, #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ #define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */ +#define FOLL_MLOCK 0x1000 /* lock present pages */ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, void *data); -- cgit v1.2.3