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-rw-r--r--mm/mlock.c101
1 files changed, 30 insertions, 71 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index c9bd528..e6638f5 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -155,13 +155,12 @@ void munlock_vma_page(struct page *page)
*
* vma->vm_mm->mmap_sem must be held for at least read.
*/
-static long __mlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end,
- int *nonblocking)
+long __mlock_vma_pages_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end, int *nonblocking)
{
struct mm_struct *mm = vma->vm_mm;
unsigned long addr = start;
- int nr_pages = (end - start) / PAGE_SIZE;
+ unsigned long nr_pages = (end - start) / PAGE_SIZE;
int gup_flags;
VM_BUG_ON(start & ~PAGE_MASK);
@@ -186,6 +185,10 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma,
if (vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))
gup_flags |= FOLL_FORCE;
+ /*
+ * We made sure addr is within a VMA, so the following will
+ * not result in a stack expansion that recurses back here.
+ */
return __get_user_pages(current, mm, addr, nr_pages, gup_flags,
NULL, NULL, nonblocking);
}
@@ -202,56 +205,6 @@ static int __mlock_posix_error_return(long retval)
return retval;
}
-/**
- * mlock_vma_pages_range() - mlock pages in specified vma range.
- * @vma - the vma containing the specfied address range
- * @start - starting address in @vma to mlock
- * @end - end address [+1] in @vma to mlock
- *
- * For mmap()/mremap()/expansion of mlocked vma.
- *
- * return 0 on success for "normal" vmas.
- *
- * return number of pages [> 0] to be removed from locked_vm on success
- * of "special" vmas.
- */
-long mlock_vma_pages_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
-{
- int nr_pages = (end - start) / PAGE_SIZE;
- BUG_ON(!(vma->vm_flags & VM_LOCKED));
-
- /*
- * filter unlockable vmas
- */
- if (vma->vm_flags & (VM_IO | VM_PFNMAP))
- goto no_mlock;
-
- if (!((vma->vm_flags & VM_DONTEXPAND) ||
- is_vm_hugetlb_page(vma) ||
- vma == get_gate_vma(current->mm))) {
-
- __mlock_vma_pages_range(vma, start, end, NULL);
-
- /* Hide errors from mmap() and other callers */
- return 0;
- }
-
- /*
- * User mapped kernel pages or huge pages:
- * make these pages present to populate the ptes, but
- * fall thru' to reset VM_LOCKED--no need to unlock, and
- * return nr_pages so these don't get counted against task's
- * locked limit. huge pages are already counted against
- * locked vm limit.
- */
- make_pages_present(start, end);
-
-no_mlock:
- vma->vm_flags &= ~VM_LOCKED; /* and don't come back! */
- return nr_pages; /* error or pages NOT mlocked */
-}
-
/*
* munlock_vma_pages_range() - munlock all pages in the vma range.'
* @vma - vma containing range to be munlock()ed.
@@ -303,7 +256,7 @@ void munlock_vma_pages_range(struct vm_area_struct *vma,
*
* Filters out "special" vmas -- VM_LOCKED never gets set for these, and
* munlock is a no-op. However, for some special vmas, we go ahead and
- * populate the ptes via make_pages_present().
+ * populate the ptes.
*
* For vmas that pass the filters, merge/split as appropriate.
*/
@@ -391,9 +344,9 @@ static int do_mlock(unsigned long start, size_t len, int on)
/* Here we know that vma->vm_start <= nstart < vma->vm_end. */
- newflags = vma->vm_flags | VM_LOCKED;
- if (!on)
- newflags &= ~VM_LOCKED;
+ newflags = vma->vm_flags & ~VM_LOCKED;
+ if (on)
+ newflags |= VM_LOCKED | VM_POPULATE;
tmp = vma->vm_end;
if (tmp > end)
@@ -416,13 +369,20 @@ static int do_mlock(unsigned long start, size_t len, int on)
return error;
}
-static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
+/*
+ * __mm_populate - populate and/or mlock pages within a range of address space.
+ *
+ * This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
+ * flags. VMAs must be already marked with the desired vm_flags, and
+ * mmap_sem must not be held.
+ */
+int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
{
struct mm_struct *mm = current->mm;
unsigned long end, nstart, nend;
struct vm_area_struct *vma = NULL;
int locked = 0;
- int ret = 0;
+ long ret = 0;
VM_BUG_ON(start & ~PAGE_MASK);
VM_BUG_ON(len != PAGE_ALIGN(len));
@@ -446,7 +406,8 @@ static int do_mlock_pages(unsigned long start, size_t len, int ignore_errors)
* range with the first VMA. Also, skip undesirable VMA types.
*/
nend = min(end, vma->vm_end);
- if (vma->vm_flags & (VM_IO | VM_PFNMAP))
+ if ((vma->vm_flags & (VM_IO | VM_PFNMAP | VM_POPULATE)) !=
+ VM_POPULATE)
continue;
if (nstart < vma->vm_start)
nstart = vma->vm_start;
@@ -498,7 +459,7 @@ SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
error = do_mlock(start, len, 1);
up_write(&current->mm->mmap_sem);
if (!error)
- error = do_mlock_pages(start, len, 0);
+ error = __mm_populate(start, len, 0);
return error;
}
@@ -519,18 +480,18 @@ static int do_mlockall(int flags)
struct vm_area_struct * vma, * prev = NULL;
if (flags & MCL_FUTURE)
- current->mm->def_flags |= VM_LOCKED;
+ current->mm->def_flags |= VM_LOCKED | VM_POPULATE;
else
- current->mm->def_flags &= ~VM_LOCKED;
+ current->mm->def_flags &= ~(VM_LOCKED | VM_POPULATE);
if (flags == MCL_FUTURE)
goto out;
for (vma = current->mm->mmap; vma ; vma = prev->vm_next) {
vm_flags_t newflags;
- newflags = vma->vm_flags | VM_LOCKED;
- if (!(flags & MCL_CURRENT))
- newflags &= ~VM_LOCKED;
+ newflags = vma->vm_flags & ~VM_LOCKED;
+ if (flags & MCL_CURRENT)
+ newflags |= VM_LOCKED | VM_POPULATE;
/* Ignore errors */
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
@@ -564,10 +525,8 @@ SYSCALL_DEFINE1(mlockall, int, flags)
capable(CAP_IPC_LOCK))
ret = do_mlockall(flags);
up_write(&current->mm->mmap_sem);
- if (!ret && (flags & MCL_CURRENT)) {
- /* Ignore errors */
- do_mlock_pages(0, TASK_SIZE, 1);
- }
+ if (!ret && (flags & MCL_CURRENT))
+ mm_populate(0, TASK_SIZE);
out:
return ret;
}
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