From: "Liam R. Howlett" <Liam.Howlett@xxxxxxxxxx>
Don't use the mm_struct linked list or the vma->vm_next in prep for removal
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
fs/userfaultfd.c | 34 +++++++++++++++++++++++++++-------
1 file changed, 27 insertions(+), 7 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 003f0d31743e..bd181f922999 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -606,14 +606,18 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
if (release_new_ctx) {
struct vm_area_struct *vma;
struct mm_struct *mm = release_new_ctx->mm;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
/* the various vma->vm_userfaultfd_ctx still points to it */
mmap_write_lock(mm);
- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ mas_lock(&mas);
+ mas_for_each(&mas, vma, ULONG_MAX) {
if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) {
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
vma->vm_flags &= ~__VM_UFFD_FLAGS;
}
+ }
+ mas_unlock(&mas);
mmap_write_unlock(mm);
userfaultfd_ctx_put(release_new_ctx);
@@ -798,7 +802,10 @@ int userfaultfd_unmap_prep(struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct list_head *unmaps)
{
- for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
+ MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_start, vma->vm_start);
+
+ rcu_read_lock();
+ mas_for_each(&mas, vma, end) {
struct userfaultfd_unmap_ctx *unmap_ctx;
struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
@@ -817,6 +824,7 @@ int userfaultfd_unmap_prep(struct vm_area_struct *vma,
unmap_ctx->end = end;
list_add_tail(&unmap_ctx->list, unmaps);
}
+ rcu_read_unlock();
return 0;
}
@@ -848,6 +856,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
/* len == 0 means wake all */
struct userfaultfd_wake_range range = { .len = 0, };
unsigned long new_flags;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
WRITE_ONCE(ctx->released, true);
@@ -863,9 +872,11 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
* taking the mmap_lock for writing.
*/
mmap_write_lock(mm);
+ mas_lock(&mas);
prev = NULL;
- for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ mas_for_each(&mas, vma, ULONG_MAX) {
cond_resched();
+
BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^
!!(vma->vm_flags & __VM_UFFD_FLAGS));
if (vma->vm_userfaultfd_ctx.ctx != ctx) {
@@ -885,6 +896,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
vma->vm_flags = new_flags;
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
}
+ mas_unlock(&mas);
mmap_write_unlock(mm);
mmput(mm);
wakeup:
@@ -1281,6 +1293,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
bool found;
bool basic_ioctls;
unsigned long start, end, vma_end;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
user_uffdio_register = (struct uffdio_register __user *) arg;
@@ -1323,6 +1336,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
goto out;
mmap_write_lock(mm);
+ mas_lock(&mas);
vma = find_vma_prev(mm, start, &prev);
if (!vma)
goto out_unlock;
@@ -1348,7 +1362,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
*/
found = false;
basic_ioctls = false;
- for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
+ mas_set(&mas, vma->vm_start);
+ mas_for_each(&mas, cur, end) {
cond_resched();
BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
@@ -1466,9 +1481,10 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
skip:
prev = vma;
start = vma->vm_end;
- vma = vma->vm_next;
+ vma = vma_next(mm, vma);
} while (vma && vma->vm_start < end);
out_unlock:
+ mas_unlock(&mas);
mmap_write_unlock(mm);
mmput(mm);
if (!ret) {
@@ -1511,6 +1527,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
bool found;
unsigned long start, end, vma_end;
const void __user *buf = (void __user *)arg;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
ret = -EFAULT;
if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
@@ -1529,6 +1546,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
goto out;
mmap_write_lock(mm);
+ mas_lock(&mas);
vma = find_vma_prev(mm, start, &prev);
if (!vma)
goto out_unlock;
@@ -1554,7 +1572,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
*/
found = false;
ret = -EINVAL;
- for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
+ mas_set(&mas, vma->vm_start);
+ mas_for_each(&mas, cur, end) {
cond_resched();
BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
@@ -1640,9 +1659,10 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
skip:
prev = vma;
start = vma->vm_end;
- vma = vma->vm_next;
+ vma = vma_next(mm, vma);
} while (vma && vma->vm_start < end);
out_unlock:
+ mas_unlock(&mas);
mmap_write_unlock(mm);
mmput(mm);
out:
--
2.30.2
