userfaultfd: non-cooperative: add event for memory unmaps

When a non-cooperative userfaultfd monitor copies pages in the
background, it may encounter regions that were already unmapped.
Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely
changes in the virtual memory layout.

Since there might be different uffd contexts for the affected VMAs, we
first should create a temporary representation for the unmap event for
each uffd context and then notify them one by one to the appropriate
userfault file descriptors.

The event notification occurs after the mmap_sem has been released.

[arnd@arndb.de: fix nommu build]
  Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de
[mhocko@suse.com: fix nommu build]
  Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

15 files changed, 160 insertions, 45 deletions

diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index f9dbfb14af33..093517e85a6c 100644
--- a/arch/mips/kernel/vdso.c
+++ b/arch/mips/kernel/vdso.c
@@ -111,7 +111,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
         base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
                            VM_READ|VM_WRITE|VM_EXEC|
                            VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-                           0);
+                           0, NULL);
         if (IS_ERR_VALUE(base)) {
                 ret = base;
                 goto out;
diff --git a/arch/tile/mm/elf.c b/arch/tile/mm/elf.c
index 6225cc998db1..889901824400 100644
--- a/arch/tile/mm/elf.c
+++ b/arch/tile/mm/elf.c
@@ -143,7 +143,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
                 unsigned long addr = MEM_USER_INTRPT;
                 addr = mmap_region(NULL, addr, INTRPT_SIZE,
                                    VM_READ|VM_EXEC|
-                                   VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 0);
+                                   VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 0, NULL);
                 if (addr > (unsigned long) -PAGE_SIZE)
                         retval = (int) addr;
         }
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 10820f6cefbf..572cee3fccff 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -186,7 +186,7 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
 
         if (IS_ERR(vma)) {
                 ret = PTR_ERR(vma);
-                do_munmap(mm, text_start, image->size);
+                do_munmap(mm, text_start, image->size, NULL);
         } else {
                 current->mm->context.vdso = (void __user *)text_start;
                 current->mm->context.vdso_image = image;
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index aad4ac386f98..c98079684bdb 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -51,7 +51,7 @@ static unsigned long mpx_mmap(unsigned long len)
 
         down_write(&mm->mmap_sem);
         addr = do_mmap(NULL, 0, len, PROT_READ | PROT_WRITE,
-                        MAP_ANONYMOUS | MAP_PRIVATE, VM_MPX, 0, &populate);
+                       MAP_ANONYMOUS | MAP_PRIVATE, VM_MPX, 0, &populate, NULL);
         up_write(&mm->mmap_sem);
         if (populate)
                 mm_populate(addr, populate);
@@ -893,7 +893,7 @@ static int unmap_entire_bt(struct mm_struct *mm,
          * avoid recursion, do_munmap() will check whether it comes
          * from one bounds table through VM_MPX flag.
          */
-        return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm));
+        return do_munmap(mm, bt_addr, mpx_bt_size_bytes(mm), NULL);
 }
 
 static int try_unmap_single_bt(struct mm_struct *mm,
diff --git a/fs/aio.c b/fs/aio.c
index 873b4ca82ccb..7e2ab9c8e39c 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -512,7 +512,7 @@ static int aio_setup_ring(struct kioctx *ctx)
 
         ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
                                        PROT_READ | PROT_WRITE,
-                                       MAP_SHARED, 0, &unused);
+                                       MAP_SHARED, 0, &unused, NULL);
         up_write(&mm->mmap_sem);
         if (IS_ERR((void *)ctx->mmap_base)) {
                 ctx->mmap_size = 0;
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index f52d8e857ff7..885d445afa0d 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -388,7 +388,7 @@ static int remap_oldmem_pfn_checked(struct vm_area_struct *vma,
         }
         return 0;
 fail:
-        do_munmap(vma->vm_mm, from, len);
+        do_munmap(vma->vm_mm, from, len, NULL);
         return -EAGAIN;
 }
 
@@ -481,7 +481,7 @@ static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 
         return 0;
 fail:
-        do_munmap(vma->vm_mm, vma->vm_start, len);
+        do_munmap(vma->vm_mm, vma->vm_start, len, NULL);
         return -EAGAIN;
 }
 #else
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 8fe601b4875e..4c78458ea78d 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -71,6 +71,13 @@ struct userfaultfd_fork_ctx {
         struct list_head list;
 };
 
+struct userfaultfd_unmap_ctx {
+        struct userfaultfd_ctx *ctx;
+        unsigned long start;
+        unsigned long end;
+        struct list_head list;
+};
+
 struct userfaultfd_wait_queue {
         struct uffd_msg msg;
         wait_queue_t wq;
@@ -709,6 +716,64 @@ void userfaultfd_remove(struct vm_area_struct *vma,
         down_read(&mm->mmap_sem);
 }
 
+static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps,
+                          unsigned long start, unsigned long end)
+{
+        struct userfaultfd_unmap_ctx *unmap_ctx;
+
+        list_for_each_entry(unmap_ctx, unmaps, list)
+                if (unmap_ctx->ctx == ctx && unmap_ctx->start == start &&
+                    unmap_ctx->end == end)
+                        return true;
+
+        return false;
+}
+
+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) {
+                struct userfaultfd_unmap_ctx *unmap_ctx;
+                struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx;
+
+                if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) ||
+                    has_unmap_ctx(ctx, unmaps, start, end))
+                        continue;
+
+                unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL);
+                if (!unmap_ctx)
+                        return -ENOMEM;
+
+                userfaultfd_ctx_get(ctx);
+                unmap_ctx->ctx = ctx;
+                unmap_ctx->start = start;
+                unmap_ctx->end = end;
+                list_add_tail(&unmap_ctx->list, unmaps);
+        }
+
+        return 0;
+}
+
+void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf)
+{
+        struct userfaultfd_unmap_ctx *ctx, *n;
+        struct userfaultfd_wait_queue ewq;
+
+        list_for_each_entry_safe(ctx, n, uf, list) {
+                msg_init(&ewq.msg);
+
+                ewq.msg.event = UFFD_EVENT_UNMAP;
+                ewq.msg.arg.remove.start = ctx->start;
+                ewq.msg.arg.remove.end = ctx->end;
+
+                userfaultfd_event_wait_completion(ctx->ctx, &ewq);
+
+                list_del(&ctx->list);
+                kfree(ctx);
+        }
+}
+
 static int userfaultfd_release(struct inode *inode, struct file *file)
 {
         struct userfaultfd_ctx *ctx = file->private_data;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c65aa43b5712..c6fcba1d1ae5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2090,18 +2090,22 @@ extern int install_special_mapping(struct mm_struct *mm,
 extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
 
 extern unsigned long mmap_region(struct file *file, unsigned long addr,
-        unsigned long len, vm_flags_t vm_flags, unsigned long pgoff);
+        unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
+        struct list_head *uf);
 extern unsigned long do_mmap(struct file *file, unsigned long addr,
         unsigned long len, unsigned long prot, unsigned long flags,
-        vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate);
-extern int do_munmap(struct mm_struct *, unsigned long, size_t);
+        vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
+        struct list_head *uf);
+extern int do_munmap(struct mm_struct *, unsigned long, size_t,
+                     struct list_head *uf);
 
 static inline unsigned long
 do_mmap_pgoff(struct file *file, unsigned long addr,
         unsigned long len, unsigned long prot, unsigned long flags,
-        unsigned long pgoff, unsigned long *populate)
+        unsigned long pgoff, unsigned long *populate,
+        struct list_head *uf)
 {
-        return do_mmap(file, addr, len, prot, flags, 0, pgoff, populate);
+        return do_mmap(file, addr, len, prot, flags, 0, pgoff, populate, uf);
 }
 
 #ifdef CONFIG_MMU
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 2521542f6c07..a40be5d0661b 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -66,6 +66,12 @@ extern void 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 void userfaultfd_unmap_complete(struct mm_struct *mm,
+                                       struct list_head *uf);
+
 #else /* CONFIG_USERFAULTFD */
 
 /* mm helpers */
@@ -118,6 +124,18 @@ static inline void userfaultfd_remove(struct vm_area_struct *vma,
                                       unsigned long end)
 {
 }
+
+static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
+                                         unsigned long start, unsigned long end,
+                                         struct list_head *uf)
+{
+        return 0;
+}
+
+static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
+                                              struct list_head *uf)
+{
+}
 #endif /* CONFIG_USERFAULTFD */
 
 #endif /* _LINUX_USERFAULTFD_K_H */
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index b742c40c2880..3b059530dac9 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -21,6 +21,7 @@
 #define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK |            \
                            UFFD_FEATURE_EVENT_REMAP |           \
                            UFFD_FEATURE_EVENT_REMOVE |  \
+                           UFFD_FEATURE_EVENT_UNMAP |           \
                            UFFD_FEATURE_MISSING_HUGETLBFS |     \
                            UFFD_FEATURE_MISSING_SHMEM)
 #define UFFD_API_IOCTLS                         \
@@ -110,6 +111,7 @@ struct uffd_msg {
 #define UFFD_EVENT_FORK         0x13
 #define UFFD_EVENT_REMAP        0x14
 #define UFFD_EVENT_REMOVE       0x15
+#define UFFD_EVENT_UNMAP        0x16
 
 /* flags for UFFD_EVENT_PAGEFAULT */
 #define UFFD_PAGEFAULT_FLAG_WRITE       (1<<0)  /* If this was a write fault */
@@ -158,6 +160,7 @@ struct uffdio_api {
 #define UFFD_FEATURE_EVENT_REMOVE               (1<<3)
 #define UFFD_FEATURE_MISSING_HUGETLBFS          (1<<4)
 #define UFFD_FEATURE_MISSING_SHMEM              (1<<5)
+#define UFFD_FEATURE_EVENT_UNMAP                (1<<6)
         __u64 features;
 
         __u64 ioctls;
diff --git a/ipc/shm.c b/ipc/shm.c
index 7f6537b84ef5..d7805acb44fd 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1222,7 +1222,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
                         goto invalid;
         }
 
-        addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate);
+        addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
         *raddr = addr;
         err = 0;
         if (IS_ERR_VALUE(addr))
@@ -1329,7 +1329,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
                          */
                         file = vma->vm_file;
                         size = i_size_read(file_inode(vma->vm_file));
-                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
+                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
                         /*
                          * We discovered the size of the shm segment, so
                          * break out of here and fall through to the next
@@ -1356,7 +1356,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
                 if ((vma->vm_ops == &shm_vm_ops) &&
                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
                     (vma->vm_file == file))
-                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
+                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
                 vma = next;
         }
 
@@ -1365,7 +1365,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
          * given
          */
         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
-                do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
+                do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
                 retval = 0;
         }
 
diff --git a/mm/mmap.c b/mm/mmap.c
index 13d16a2b7623..1cec28d20583 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -176,7 +176,7 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
         return next;
 }
 
-static int do_brk(unsigned long addr, unsigned long len);
+static int do_brk(unsigned long addr, unsigned long len, struct list_head *uf);
 
 SYSCALL_DEFINE1(brk, unsigned long, brk)
 {
@@ -185,6 +185,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
         struct mm_struct *mm = current->mm;
         unsigned long min_brk;
         bool populate;
+        LIST_HEAD(uf);
 
         if (down_write_killable(&mm->mmap_sem))
                 return -EINTR;
@@ -222,7 +223,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 
         /* Always allow shrinking brk. */
         if (brk <= mm->brk) {
-                if (!do_munmap(mm, newbrk, oldbrk-newbrk))
+                if (!do_munmap(mm, newbrk, oldbrk-newbrk, &uf))
                         goto set_brk;
                 goto out;
         }
@@ -232,13 +233,14 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
                 goto out;
 
         /* Ok, looks good - let it rip. */
-        if (do_brk(oldbrk, newbrk-oldbrk) < 0)
+        if (do_brk(oldbrk, newbrk-oldbrk, &uf) < 0)
                 goto out;
 
 set_brk:
         mm->brk = brk;
         populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
         up_write(&mm->mmap_sem);
+        userfaultfd_unmap_complete(mm, &uf);
         if (populate)
                 mm_populate(oldbrk, newbrk - oldbrk);
         return brk;
@@ -1304,7 +1306,8 @@ static inline int mlock_future_check(struct mm_struct *mm,
 unsigned long do_mmap(struct file *file, unsigned long addr,
                         unsigned long len, unsigned long prot,
                         unsigned long flags, vm_flags_t vm_flags,
-                        unsigned long pgoff, unsigned long *populate)
+                        unsigned long pgoff, unsigned long *populate,
+                        struct list_head *uf)
 {
         struct mm_struct *mm = current->mm;
         int pkey = 0;
@@ -1447,7 +1450,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
                         vm_flags |= VM_NORESERVE;
         }
 
-        addr = mmap_region(file, addr, len, vm_flags, pgoff);
+        addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
         if (!IS_ERR_VALUE(addr) &&
             ((vm_flags & VM_LOCKED) ||
              (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
@@ -1583,7 +1586,8 @@ static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
 }
 
 unsigned long mmap_region(struct file *file, unsigned long addr,
-                unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
+                unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
+                struct list_head *uf)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma, *prev;
@@ -1609,7 +1613,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
         /* Clear old maps */
         while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
                               &rb_parent)) {
-                if (do_munmap(mm, addr, len))
+                if (do_munmap(mm, addr, len, uf))
                         return -ENOMEM;
         }
 
@@ -2579,7 +2583,8 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
  * work.  This now handles partial unmappings.
  * Jeremy Fitzhardinge <jeremy@goop.org>
  */
-int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+              struct list_head *uf)
 {
         unsigned long end;
         struct vm_area_struct *vma, *prev, *last;
@@ -2603,6 +2608,13 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
         if (vma->vm_start >= end)
                 return 0;
 
+        if (uf) {
+                int error = userfaultfd_unmap_prep(vma, start, end, uf);
+
+                if (error)
+                        return error;
+        }
+
         /*
          * If we need to split any vma, do it now to save pain later.
          *
@@ -2668,12 +2680,14 @@ int vm_munmap(unsigned long start, size_t len)
 {
         int ret;
         struct mm_struct *mm = current->mm;
+        LIST_HEAD(uf);
 
         if (down_write_killable(&mm->mmap_sem))
                 return -EINTR;
 
-        ret = do_munmap(mm, start, len);
+        ret = do_munmap(mm, start, len, &uf);
         up_write(&mm->mmap_sem);
+        userfaultfd_unmap_complete(mm, &uf);
         return ret;
 }
 EXPORT_SYMBOL(vm_munmap);
@@ -2773,7 +2787,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 
         file = get_file(vma->vm_file);
         ret = do_mmap_pgoff(vma->vm_file, start, size,
-                        prot, flags, pgoff, &populate);
+                        prot, flags, pgoff, &populate, NULL);
         fput(file);
 out:
         up_write(&mm->mmap_sem);
@@ -2799,7 +2813,7 @@ static inline void verify_mm_writelocked(struct mm_struct *mm)
  *  anonymous maps.  eventually we may be able to do some
  *  brk-specific accounting here.
  */
-static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
+static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, struct list_head *uf)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma, *prev;
@@ -2838,7 +2852,7 @@ static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long
          */
         while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
                               &rb_parent)) {
-                if (do_munmap(mm, addr, len))
+                if (do_munmap(mm, addr, len, uf))
                         return -ENOMEM;
         }
 
@@ -2885,9 +2899,9 @@ out:
         return 0;
 }
 
-static int do_brk(unsigned long addr, unsigned long len)
+static int do_brk(unsigned long addr, unsigned long len, struct list_head *uf)
 {
-        return do_brk_flags(addr, len, 0);
+        return do_brk_flags(addr, len, 0, uf);
 }
 
 int vm_brk_flags(unsigned long addr, unsigned long len, unsigned long flags)
@@ -2895,13 +2909,15 @@ int vm_brk_flags(unsigned long addr, unsigned long len, unsigned long flags)
         struct mm_struct *mm = current->mm;
         int ret;
         bool populate;
+        LIST_HEAD(uf);
 
         if (down_write_killable(&mm->mmap_sem))
                 return -EINTR;
 
-        ret = do_brk_flags(addr, len, flags);
+        ret = do_brk_flags(addr, len, flags, &uf);
         populate = ((mm->def_flags & VM_LOCKED) != 0);
         up_write(&mm->mmap_sem);
+        userfaultfd_unmap_complete(mm, &uf);
         if (populate && !ret)
                 mm_populate(addr, len);
         return ret;
diff --git a/mm/mremap.c b/mm/mremap.c
index 8779928d6a70..8233b0105c82 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -252,7 +252,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 static unsigned long move_vma(struct vm_area_struct *vma,
                 unsigned long old_addr, unsigned long old_len,
                 unsigned long new_len, unsigned long new_addr,
-                bool *locked, struct vm_userfaultfd_ctx *uf)
+                bool *locked, struct vm_userfaultfd_ctx *uf,
+                struct list_head *uf_unmap)
 {
         struct mm_struct *mm = vma->vm_mm;
         struct vm_area_struct *new_vma;
@@ -341,7 +342,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
         if (unlikely(vma->vm_flags & VM_PFNMAP))
                 untrack_pfn_moved(vma);
 
-        if (do_munmap(mm, old_addr, old_len) < 0) {
+        if (do_munmap(mm, old_addr, old_len, uf_unmap) < 0) {
                 /* OOM: unable to split vma, just get accounts right */
                 vm_unacct_memory(excess >> PAGE_SHIFT);
                 excess = 0;
@@ -417,7 +418,8 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
 
 static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
                 unsigned long new_addr, unsigned long new_len, bool *locked,
-                struct vm_userfaultfd_ctx *uf)
+                struct vm_userfaultfd_ctx *uf,
+                struct list_head *uf_unmap)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma;
@@ -435,12 +437,12 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
         if (addr + old_len > new_addr && new_addr + new_len > addr)
                 goto out;
 
-        ret = do_munmap(mm, new_addr, new_len);
+        ret = do_munmap(mm, new_addr, new_len, NULL);
         if (ret)
                 goto out;
 
         if (old_len >= new_len) {
-                ret = do_munmap(mm, addr+new_len, old_len - new_len);
+                ret = do_munmap(mm, addr+new_len, old_len - new_len, uf_unmap);
                 if (ret && old_len != new_len)
                         goto out;
                 old_len = new_len;
@@ -462,7 +464,8 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
         if (offset_in_page(ret))
                 goto out1;
 
-        ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf);
+        ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf,
+                       uf_unmap);
         if (!(offset_in_page(ret)))
                 goto out;
 out1:
@@ -502,6 +505,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
         unsigned long charged = 0;
         bool locked = false;
         struct vm_userfaultfd_ctx uf = NULL_VM_UFFD_CTX;
+        LIST_HEAD(uf_unmap);
 
         if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
                 return ret;
@@ -528,7 +532,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 
         if (flags & MREMAP_FIXED) {
                 ret = mremap_to(addr, old_len, new_addr, new_len,
-                                &locked, &uf);
+                                &locked, &uf, &uf_unmap);
                 goto out;
         }
 
@@ -538,7 +542,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
          * do_munmap does all the needed commit accounting
          */
         if (old_len >= new_len) {
-                ret = do_munmap(mm, addr+new_len, old_len - new_len);
+                ret = do_munmap(mm, addr+new_len, old_len - new_len, &uf_unmap);
                 if (ret && old_len != new_len)
                         goto out;
                 ret = addr;
@@ -598,7 +602,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
                 }
 
                 ret = move_vma(vma, addr, old_len, new_len, new_addr,
-                               &locked, &uf);
+                               &locked, &uf, &uf_unmap);
         }
 out:
         if (offset_in_page(ret)) {
@@ -609,5 +613,6 @@ out:
         if (locked && new_len > old_len)
                 mm_populate(new_addr + old_len, new_len - old_len);
         mremap_userfaultfd_complete(&uf, addr, new_addr, old_len);
+        userfaultfd_unmap_complete(mm, &uf_unmap);
         return ret;
 }
diff --git a/mm/nommu.c b/mm/nommu.c
index 215c62296028..fe9f4fa4a7a7 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1205,7 +1205,8 @@ unsigned long do_mmap(struct file *file,
                         unsigned long flags,
                         vm_flags_t vm_flags,
                         unsigned long pgoff,
-                        unsigned long *populate)
+                        unsigned long *populate,
+                        struct list_head *uf)
 {
         struct vm_area_struct *vma;
         struct vm_region *region;
@@ -1577,7 +1578,7 @@ static int shrink_vma(struct mm_struct *mm,
  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
  *   VMA, though it need not cover the whole VMA
  */
-int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
+int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf)
 {
         struct vm_area_struct *vma;
         unsigned long end;
@@ -1643,7 +1644,7 @@ int vm_munmap(unsigned long addr, size_t len)
         int ret;
 
         down_write(&mm->mmap_sem);
-        ret = do_munmap(mm, addr, len);
+        ret = do_munmap(mm, addr, len, NULL);
         up_write(&mm->mmap_sem);
         return ret;
 }
diff --git a/mm/util.c b/mm/util.c
index 3cb2164f4099..b8f538863b5a 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -11,6 +11,7 @@
 #include <linux/mman.h>
 #include <linux/hugetlb.h>
 #include <linux/vmalloc.h>
+#include <linux/userfaultfd_k.h>
 
 #include <asm/sections.h>
 #include <linux/uaccess.h>
@@ -297,14 +298,16 @@ unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
         unsigned long ret;
         struct mm_struct *mm = current->mm;
         unsigned long populate;
+        LIST_HEAD(uf);
 
         ret = security_mmap_file(file, prot, flag);
         if (!ret) {
                 if (down_write_killable(&mm->mmap_sem))
                         return -EINTR;
                 ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
-                                    &populate);
+                                    &populate, &uf);
                 up_write(&mm->mmap_sem);
+                userfaultfd_unmap_complete(mm, &uf);
                 if (populate)
                         mm_populate(ret, populate);
         }