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authorMichel Lespinasse <walken@google.com>2013-03-28 19:26:23 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-03-28 20:45:51 -0400
commit09a9f1d27892255cfb9c91203f19476765e2d8d1 (patch)
treee6f0985223c87408773c3b81428935d3ce99931b /mm
parent0776ce03b1348d39ba3035ea3ee3d268a42912ce (diff)
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 4723ac8d2fc2..87da3590c61e 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -204,10 +204,8 @@ get_write_lock:
204 unsigned long addr; 204 unsigned long addr;
205 struct file *file = get_file(vma->vm_file); 205 struct file *file = get_file(vma->vm_file);
206 206
207 vm_flags = vma->vm_flags; 207 addr = mmap_region(file, start, size,
208 if (!(flags & MAP_NONBLOCK)) 208 vma->vm_flags, pgoff);
209 vm_flags |= VM_POPULATE;
210 addr = mmap_region(file, start, size, vm_flags, pgoff);
211 fput(file); 209 fput(file);
212 if (IS_ERR_VALUE(addr)) { 210 if (IS_ERR_VALUE(addr)) {
213 err = addr; 211 err = addr;
@@ -226,12 +224,6 @@ get_write_lock:
226 mutex_unlock(&mapping->i_mmap_mutex); 224 mutex_unlock(&mapping->i_mmap_mutex);
227 } 225 }
228 226
229 if (!(flags & MAP_NONBLOCK) && !(vma->vm_flags & VM_POPULATE)) {
230 if (!has_write_lock)
231 goto get_write_lock;
232 vma->vm_flags |= VM_POPULATE;
233 }
234
235 if (vma->vm_flags & VM_LOCKED) { 227 if (vma->vm_flags & VM_LOCKED) {
236 /* 228 /*
237 * drop PG_Mlocked flag for over-mapped range 229 * drop PG_Mlocked flag for over-mapped range
diff --git a/mm/mlock.c b/mm/mlock.c
index 1c5e33fce639..79b7cf7d1bca 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)
358 358
359 newflags = vma->vm_flags & ~VM_LOCKED; 359 newflags = vma->vm_flags & ~VM_LOCKED;
360 if (on) 360 if (on)
361 newflags |= VM_LOCKED | VM_POPULATE; 361 newflags |= VM_LOCKED;
362 362
363 tmp = vma->vm_end; 363 tmp = vma->vm_end;
364 if (tmp > end) 364 if (tmp > end)
@@ -418,8 +418,7 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
418 * range with the first VMA. Also, skip undesirable VMA types. 418 * range with the first VMA. Also, skip undesirable VMA types.
419 */ 419 */
420 nend = min(end, vma->vm_end); 420 nend = min(end, vma->vm_end);
421 if ((vma->vm_flags & (VM_IO | VM_PFNMAP | VM_POPULATE)) != 421 if (vma->vm_flags & (VM_IO | VM_PFNMAP))
422 VM_POPULATE)
423 continue; 422 continue;
424 if (nstart < vma->vm_start) 423 if (nstart < vma->vm_start)
425 nstart = vma->vm_start; 424 nstart = vma->vm_start;
@@ -492,9 +491,9 @@ static int do_mlockall(int flags)
492 struct vm_area_struct * vma, * prev = NULL; 491 struct vm_area_struct * vma, * prev = NULL;
493 492
494 if (flags & MCL_FUTURE) 493 if (flags & MCL_FUTURE)
495 current->mm->def_flags |= VM_LOCKED | VM_POPULATE; 494 current->mm->def_flags |= VM_LOCKED;
496 else 495 else
497 current->mm->def_flags &= ~(VM_LOCKED | VM_POPULATE); 496 current->mm->def_flags &= ~VM_LOCKED;
498 if (flags == MCL_FUTURE) 497 if (flags == MCL_FUTURE)
499 goto out; 498 goto out;
500 499
@@ -503,7 +502,7 @@ static int do_mlockall(int flags)
503 502
504 newflags = vma->vm_flags & ~VM_LOCKED; 503 newflags = vma->vm_flags & ~VM_LOCKED;
505 if (flags & MCL_CURRENT) 504 if (flags & MCL_CURRENT)
506 newflags |= VM_LOCKED | VM_POPULATE; 505 newflags |= VM_LOCKED;
507 506
508 /* Ignore errors */ 507 /* Ignore errors */
509 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags); 508 mlock_fixup(vma, &prev, vma->vm_start, vma->vm_end, newflags);
diff --git a/mm/mmap.c b/mm/mmap.c
index 2664a47cec93..6466699b16cb 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1306,7 +1306,9 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1306 } 1306 }
1307 1307
1308 addr = mmap_region(file, addr, len, vm_flags, pgoff); 1308 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1309 if (!IS_ERR_VALUE(addr) && (vm_flags & VM_POPULATE)) 1309 if (!IS_ERR_VALUE(addr) &&
1310 ((vm_flags & VM_LOCKED) ||
1311 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1310 *populate = len; 1312 *populate = len;
1311 return addr; 1313 return addr;
1312} 1314}