aboutsummaryrefslogtreecommitdiff
path: root/mm
diff options
context:
space:
mode:
authorMichel Lespinasse <walken@google.com>2013-03-28 16:26:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-03-28 17:45:51 -0700
commit09a9f1d27892255cfb9c91203f19476765e2d8d1 (patch)
treee6f0985223c87408773c3b81428935d3ce99931b /mm
parent0776ce03b1348d39ba3035ea3ee3d268a42912ce (diff)
downloadvexpress-lsk-09a9f1d27892255cfb9c91203f19476765e2d8d1.tar.gz
Revert "mm: introduce VM_POPULATE flag to better deal with racy userspace programs"
This reverts commit 186930500985 ("mm: introduce VM_POPULATE flag to better deal with racy userspace programs"). VM_POPULATE only has any effect when userspace plays racy games with vmas by trying to unmap and remap memory regions that mmap or mlock are operating on. Also, the only effect of VM_POPULATE when userspace plays such games is that it avoids populating new memory regions that get remapped into the address range that was being operated on by the original mmap or mlock calls. Let's remove VM_POPULATE as there isn't any strong argument to mandate a new vm_flag. Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/fremap.c12
-rw-r--r--mm/mlock.c11
-rw-r--r--mm/mmap.c4
3 files changed, 10 insertions, 17 deletions
diff --git a/mm/fremap.c b/mm/fremap.c
index 4723ac8d2fc..87da3590c61 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -204,10 +204,8 @@ get_write_lock:
unsigned long addr;
struct file *file = get_file(vma->vm_file);
- vm_flags = vma->vm_flags;
- if (!(flags & MAP_NONBLOCK))
- vm_flags |= VM_POPULATE;
- addr = mmap_region(file, start, size, vm_flags, pgoff);
+ addr = mmap_region(file, start, size,
+ vma->vm_flags, pgoff);
fput(file);
if (IS_ERR_VALUE(addr)) {
err = addr;
@@ -226,12 +224,6 @@ get_write_lock:
mutex_unlock(&mapping->i_mmap_mutex);
}
- if (!(flags & MAP_NONBLOCK) && !(vma->vm_flags & VM_POPULATE)) {
- if (!has_write_lock)
- goto get_write_lock;
- vma->vm_flags |= VM_POPULATE;
- }
-
if (vma->vm_flags & VM_LOCKED) {
/*
* drop PG_Mlocked flag for over-mapped range
diff --git a/mm/mlock.c b/mm/mlock.c
index 1c5e33fce63..79b7cf7d1bc 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -358,7 +358,7 @@ static int do_mlock(unsigned long start, size_t len, int on)
newflags = vma->vm_flags & ~VM_LOCKED;
if (on)
- newflags |= VM_LOCKED | VM_POPULATE;
+ newflags |= VM_LOCKED;
tmp = vma->vm_end;
if (tmp > end)
@@ -418,8 +418,7 @@ int __mm_populate(unsigned long start, unsigned long 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 | VM_POPULATE)) !=
- VM_POPULATE)
+ if (vma->vm_flags & (VM_IO | VM_PFNMAP))
continue;
if (nstart < vma->vm_start)
nstart = vma->vm_start;
@@ -492,9 +491,9 @@ static int do_mlockall(int flags)
struct vm_area_struct * vma, * prev = NULL;
if (flags & MCL_FUTURE)
- current->mm->def_flags |= VM_LOCKED | VM_POPULATE;
+ current->mm->def_flags |= VM_LOCKED;
else
- current->mm->def_flags &= ~(VM_LOCKED | VM_POPULATE);
+ current->mm->def_flags &= ~VM_LOCKED;
if (flags == MCL_FUTURE)
goto out;
@@ -503,7 +502,7 @@ static int do_mlockall(int flags)
newflags = vma->vm_flags & ~VM_LOCKED;
if (flags & MCL_CURRENT)
- newflags |= VM_LOCKED | VM_POPULATE;
+ newflags |= VM_LOCKED;
/* Ignore errors */
mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
diff --git a/mm/mmap.c b/mm/mmap.c
index 2664a47cec9..6466699b16c 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1306,7 +1306,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
}
addr = mmap_region(file, addr, len, vm_flags, pgoff);
- if (!IS_ERR_VALUE(addr) && (vm_flags & VM_POPULATE))
+ if (!IS_ERR_VALUE(addr) &&
+ ((vm_flags & VM_LOCKED) ||
+ (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
*populate = len;
return addr;
}