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);
diff --git a/kernel/fork.c b/kernel/fork.c
index 6ac894244d39..a30fae45b486 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -454,7 +454,8 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
tmp->vm_mm = mm;
if (anon_vma_fork(tmp, mpnt))
goto fail_nomem_anon_vma_fork;
- tmp->vm_flags &= ~(VM_LOCKED|VM_UFFD_MISSING|VM_UFFD_WP);
+ tmp->vm_flags &=
+ ~(VM_LOCKED|VM_LOCKONFAULT|VM_UFFD_MISSING|VM_UFFD_WP);
tmp->vm_next = tmp->vm_prev = NULL;
tmp->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
file = tmp->vm_file;
diff --git a/mm/debug.c b/mm/debug.c
index 6c1b3ea61bfd..e784110fb51d 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -125,6 +125,7 @@ static const struct trace_print_flags vmaflags_names[] = {
{VM_GROWSDOWN, "growsdown" },
{VM_PFNMAP, "pfnmap" },
{VM_DENYWRITE, "denywrite" },
+ {VM_LOCKONFAULT, "lockonfault" },
{VM_LOCKED, "locked" },
{VM_IO, "io" },
{VM_SEQ_READ, "seqread" },
diff --git a/mm/gup.c b/mm/gup.c
index a798293fc648..deafa2c91b36 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -129,7 +129,7 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
*/
mark_page_accessed(page);
}
- if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) {
+ if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
/*
* The preliminary mapping check is mainly to avoid the
* pointless overhead of lock_page on the ZERO_PAGE
@@ -299,6 +299,9 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
unsigned int fault_flags = 0;
int ret;
+ /* mlock all present pages, but do not fault in new pages */
+ if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
+ return -ENOENT;
/* For mm_populate(), just skip the stack guard page. */
if ((*flags & FOLL_POPULATE) &&
(stack_guard_page_start(vma, address) ||
@@ -890,7 +893,10 @@ long populate_vma_page_range(struct vm_area_struct *vma,
VM_BUG_ON_VMA(end > vma->vm_end, vma);
VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_sem), mm);
- gup_flags = FOLL_TOUCH | FOLL_POPULATE;
+ gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
+ if (vma->vm_flags & VM_LOCKONFAULT)
+ gup_flags &= ~FOLL_POPULATE;
+
/*
* We want to touch writable mappings with a write fault in order
* to break COW, except for shared mappings because these don't COW
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3fd0311c3ba7..f5c08b46fef8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1307,7 +1307,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
pmd, _pmd, 1))
update_mmu_cache_pmd(vma, addr, pmd);
}
- if ((flags & FOLL_POPULATE) && (vma->vm_flags & VM_LOCKED)) {
+ if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
if (page->mapping && trylock_page(page)) {
lru_add_drain();
if (page->mapping)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 241de2712b36..74ef0c6a25dd 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4137,8 +4137,8 @@ static unsigned long page_table_shareable(struct vm_area_struct *svma,
unsigned long s_end = sbase + PUD_SIZE;
/* Allow segments to share if only one is marked locked */
- unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED;
- unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED;
+ unsigned long vm_flags = vma->vm_flags & VM_LOCKED_CLEAR_MASK;
+ unsigned long svm_flags = svma->vm_flags & VM_LOCKED_CLEAR_MASK;
/*
* match the virtual addresses, permission and the alignment of the
diff --git a/mm/mlock.c b/mm/mlock.c
index 35dcf8fa7195..ca3894113b97 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -422,7 +422,7 @@ static unsigned long __munlock_pagevec_fill(struct pagevec *pvec,
void munlock_vma_pages_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
- vma->vm_flags &= ~VM_LOCKED;
+ vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
while (start < end) {
struct page *page = NULL;
diff --git a/mm/mmap.c b/mm/mmap.c
index 220effde8ea3..2ce04a649f6b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1661,7 +1661,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
vma == get_gate_vma(current->mm)))
mm->locked_vm += (len >> PAGE_SHIFT);
else
- vma->vm_flags &= ~VM_LOCKED;
+ vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
}
if (file)