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 | 49 ++++++++++++++++++++++-------------
include/linux/userfaultfd_k.h | 7 +++--
mm/mmap.c | 12 ++++-----
3 files changed, 40 insertions(+), 28 deletions(-)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 22bf14ab2d16..2880025598c7 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -606,14 +606,16 @@ 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;
+ VMA_ITERATOR(vmi, mm, 0);
/* the various vma->vm_userfaultfd_ctx still points to it */
mmap_write_lock(mm);
- for (vma = mm->mmap; vma; vma = vma->vm_next)
+ for_each_vma(vmi, vma) {
if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) {
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
vma->vm_flags &= ~__VM_UFFD_FLAGS;
}
+ }
mmap_write_unlock(mm);
userfaultfd_ctx_put(release_new_ctx);
@@ -794,11 +796,13 @@ static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps,
return false;
}
-int userfaultfd_unmap_prep(struct vm_area_struct *vma,
- unsigned long start, unsigned long end,
- struct list_head *unmaps)
+int userfaultfd_unmap_prep(struct mm_struct *mm, unsigned long start,
+ unsigned long end, struct list_head *unmaps)
{
- for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
+ VMA_ITERATOR(vmi, mm, start);
+ struct vm_area_struct *vma;
+
+ for_each_vma_range(vmi, vma, end) {
struct userfaultfd_unmap_ctx *unmap_ctx;
struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
@@ -848,6 +852,7 @@ 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);
@@ -864,7 +869,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
*/
mmap_write_lock(mm);
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));
@@ -1281,6 +1286,7 @@ 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;
@@ -1323,7 +1329,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
goto out;
mmap_write_lock(mm);
- vma = find_vma_prev(mm, start, &prev);
+ mas_set(&mas, start);
+ vma = mas_find(&mas, ULONG_MAX);
if (!vma)
goto out_unlock;
@@ -1348,7 +1355,7 @@ 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) {
+ for (cur = vma; cur; cur = mas_next(&mas, end - 1)) {
cond_resched();
BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
@@ -1408,8 +1415,10 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
}
BUG_ON(!found);
- if (vma->vm_start < start)
- prev = vma;
+ mas_set(&mas, start);
+ prev = mas_prev(&mas, 0);
+ if (prev != vma)
+ mas_next(&mas, ULONG_MAX);
ret = 0;
do {
@@ -1466,8 +1475,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
skip:
prev = vma;
start = vma->vm_end;
- vma = vma->vm_next;
- } while (vma && vma->vm_start < end);
+ vma = mas_next(&mas, end - 1);
+ } while (vma);
out_unlock:
mmap_write_unlock(mm);
mmput(mm);
@@ -1511,6 +1520,7 @@ 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)))
@@ -1529,7 +1539,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
goto out;
mmap_write_lock(mm);
- vma = find_vma_prev(mm, start, &prev);
+ mas_set(&mas, start);
+ vma = mas_find(&mas, ULONG_MAX);
if (!vma)
goto out_unlock;
@@ -1554,7 +1565,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
*/
found = false;
ret = -EINVAL;
- for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) {
+ for (cur = vma; cur; cur = mas_next(&mas, end - 1)) {
cond_resched();
BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^
@@ -1574,8 +1585,10 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
}
BUG_ON(!found);
- if (vma->vm_start < start)
- prev = vma;
+ mas_set(&mas, start);
+ prev = mas_prev(&mas, 0);
+ if (prev != vma)
+ mas_next(&mas, ULONG_MAX);
ret = 0;
do {
@@ -1640,8 +1653,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
skip:
prev = vma;
start = vma->vm_end;
- vma = vma->vm_next;
- } while (vma && vma->vm_start < end);
+ vma = mas_next(&mas, end - 1);
+ } while (vma);
out_unlock:
mmap_write_unlock(mm);
mmput(mm);
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 33cea484d1ad..e0b2ec2c20f2 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -139,9 +139,8 @@ extern bool userfaultfd_remove(struct vm_area_struct *vma,
unsigned long start,
unsigned long end);
-extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
- unsigned long start, unsigned long end,
- struct list_head *uf);
+extern int userfaultfd_unmap_prep(struct mm_struct *mm, unsigned long start,
+ unsigned long end, struct list_head *uf);
extern void userfaultfd_unmap_complete(struct mm_struct *mm,
struct list_head *uf);
@@ -222,7 +221,7 @@ static inline bool userfaultfd_remove(struct vm_area_struct *vma,
return true;
}
-static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
+static inline int userfaultfd_unmap_prep(struct mm_struct *mm,
unsigned long start, unsigned long end,
struct list_head *uf)
{
diff --git a/mm/mmap.c b/mm/mmap.c
index 79b8494d83c6..dde74e0b195d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2449,7 +2449,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
* split, despite we could. This is unlikely enough
* failure that it's not worth optimizing it for.
*/
- int error = userfaultfd_unmap_prep(vma, start, end, uf);
+ int error = userfaultfd_unmap_prep(mm, start, end, uf);
if (error)
return error;
@@ -2938,10 +2938,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
goto munmap_full_vma;
}
- vma_init(&unmap, mm);
- unmap.vm_start = newbrk;
- unmap.vm_end = oldbrk;
- ret = userfaultfd_unmap_prep(&unmap, newbrk, oldbrk, uf);
+ ret = userfaultfd_unmap_prep(mm, newbrk, oldbrk, uf);
if (ret)
return ret;
ret = 1;
@@ -2954,6 +2951,9 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
}
vma->vm_end = newbrk;
+ vma_init(&unmap, mm);
+ unmap.vm_start = newbrk;
+ unmap.vm_end = oldbrk;
if (vma_mas_remove(&unmap, mas))
goto mas_store_fail;
@@ -2963,7 +2963,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
}
unmap_pages = vma_pages(&unmap);
- if (unmap.vm_flags & VM_LOCKED) {
+ if (vma->vm_flags & VM_LOCKED) {
mm->locked_vm -= unmap_pages;
munlock_vma_pages_range(&unmap, newbrk, oldbrk);
}
--
2.30.2
