userfaultfd: teach vma_merge to merge across vma->vm_userfaultfd_ctx
vma->vm_userfaultfd_ctx is yet another vma parameter that vma_merge
must be aware about so that we can merge vmas back like they were
originally before arming the userfaultfd on some memory range.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index f126923..82db4fc 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -41,6 +41,7 @@
#include <linux/notifier.h>
#include <linux/memory.h>
#include <linux/printk.h>
+#include <linux/userfaultfd_k.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -919,7 +920,8 @@
* per-vma resources, so we don't attempt to merge those.
*/
static inline int is_mergeable_vma(struct vm_area_struct *vma,
- struct file *file, unsigned long vm_flags)
+ struct file *file, unsigned long vm_flags,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
{
/*
* VM_SOFTDIRTY should not prevent from VMA merging, if we
@@ -935,6 +937,8 @@
return 0;
if (vma->vm_ops && vma->vm_ops->close)
return 0;
+ if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
+ return 0;
return 1;
}
@@ -965,9 +969,11 @@
*/
static int
can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
- struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t vm_pgoff,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
{
- if (is_mergeable_vma(vma, file, vm_flags) &&
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
if (vma->vm_pgoff == vm_pgoff)
return 1;
@@ -984,9 +990,11 @@
*/
static int
can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
- struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
+ struct anon_vma *anon_vma, struct file *file,
+ pgoff_t vm_pgoff,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
{
- if (is_mergeable_vma(vma, file, vm_flags) &&
+ if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
pgoff_t vm_pglen;
vm_pglen = vma_pages(vma);
@@ -1029,7 +1037,8 @@
struct vm_area_struct *prev, unsigned long addr,
unsigned long end, unsigned long vm_flags,
struct anon_vma *anon_vma, struct file *file,
- pgoff_t pgoff, struct mempolicy *policy)
+ pgoff_t pgoff, struct mempolicy *policy,
+ struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
{
pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
struct vm_area_struct *area, *next;
@@ -1056,14 +1065,17 @@
if (prev && prev->vm_end == addr &&
mpol_equal(vma_policy(prev), policy) &&
can_vma_merge_after(prev, vm_flags,
- anon_vma, file, pgoff)) {
+ anon_vma, file, pgoff,
+ vm_userfaultfd_ctx)) {
/*
* OK, it can. Can we now merge in the successor as well?
*/
if (next && end == next->vm_start &&
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags,
- anon_vma, file, pgoff+pglen) &&
+ anon_vma, file,
+ pgoff+pglen,
+ vm_userfaultfd_ctx) &&
is_mergeable_anon_vma(prev->anon_vma,
next->anon_vma, NULL)) {
/* cases 1, 6 */
@@ -1084,7 +1096,8 @@
if (next && end == next->vm_start &&
mpol_equal(policy, vma_policy(next)) &&
can_vma_merge_before(next, vm_flags,
- anon_vma, file, pgoff+pglen)) {
+ anon_vma, file, pgoff+pglen,
+ vm_userfaultfd_ctx)) {
if (prev && addr < prev->vm_end) /* case 4 */
err = vma_adjust(prev, prev->vm_start,
addr, prev->vm_pgoff, NULL);
@@ -1570,8 +1583,8 @@
/*
* Can we just expand an old mapping?
*/
- vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff,
- NULL);
+ vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
+ NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
if (vma)
goto out;
@@ -2757,7 +2770,7 @@
/* Can we just expand an old private anonymous mapping? */
vma = vma_merge(mm, prev, addr, addr + len, flags,
- NULL, NULL, pgoff, NULL);
+ NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
if (vma)
goto out;
@@ -2913,7 +2926,8 @@
if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
return NULL; /* should never get here */
new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
- vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
+ vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+ vma->vm_userfaultfd_ctx);
if (new_vma) {
/*
* Source vma may have been merged into new_vma