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Subject[PATCH 3/6] mm: move VM_LOCKED check to __mlock_vma_pages_range()
Date
Use a single code path for faulting in pages during mlock.

The reason to have it in this patch series is that I did not want to
update both code paths in a later change that releases mmap_sem when
blocking on disk.

Signed-off-by: Michel Lespinasse <walken@google.com>
---
mm/mlock.c | 18 +++++++++---------
1 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/mm/mlock.c b/mm/mlock.c
index 0531173..241a5d2 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -169,7 +169,7 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
VM_BUG_ON(end > vma->vm_end);
VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));

- gup_flags = FOLL_TOUCH | FOLL_MLOCK;
+ gup_flags = FOLL_TOUCH;
/*
* We want to touch writable mappings with a write fault in order
* to break COW, except for shared mappings because these don't COW
@@ -178,6 +178,9 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
gup_flags |= FOLL_WRITE;

+ if (vma->vm_flags & VM_LOCKED)
+ gup_flags |= FOLL_MLOCK;
+
/* We don't try to access the guard page of a stack vma */
if (stack_guard_page(vma, start)) {
addr += PAGE_SIZE;
@@ -456,14 +459,11 @@ static int do_mlock_pages(unsigned long start, size_t len)
/*
* Now fault in a range of pages within the first VMA.
*/
- if (vma->vm_flags & VM_LOCKED) {
- ret = __mlock_vma_pages_range(vma, nstart, nend);
- if (ret) {
- ret = __mlock_posix_error_return(ret);
- break;
- }
- } else
- make_pages_present(nstart, nend);
+ ret = __mlock_vma_pages_range(vma, nstart, nend);
+ if (ret) {
+ ret = __mlock_posix_error_return(ret);
+ break;
+ }
}
up_read(&mm->mmap_sem);
return ret; /* 0 or negative error code */
--
1.7.3.1


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