[PATCH v2 2/5] userfaultfd: non-cooperative: add event for memory unmaps

From: Mike Rapoport <hidden>
Date: 2017-01-27 21:45:55
Also in: lkml
Subsystem: aio, filesystems (vfs and infrastructure), kdump, memory management, memory management - core, memory management - userfaultfd, memory mapping, mips, proc filesystem, the rest, x86 architecture (32-bit and 64-bit), x86 entry code, x86 mm, x86 vdso · Maintainers: Benjamin LaHaise, Alexander Viro, Christian Brauner, Andrew Morton, Baoquan He, Mike Rapoport, Pasha Tatashin, Pratyush Yadav, David Hildenbrand, Liam R. Howlett, Lorenzo Stoakes, Thomas Bogendoerfer, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra

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.

Signed-off-by: Mike Rapoport <redacted>
Acked-by: Hillf Danton <redacted>
---
 arch/mips/kernel/vdso.c          |  2 +-
 arch/tile/mm/elf.c               |  2 +-
 arch/x86/entry/vdso/vma.c        |  2 +-
 arch/x86/mm/mpx.c                |  4 +--
 fs/aio.c                         |  2 +-
 fs/proc/vmcore.c                 |  4 +--
 fs/userfaultfd.c                 | 65 ++++++++++++++++++++++++++++++++++++++++
 include/linux/mm.h               | 14 +++++----
 include/linux/userfaultfd_k.h    | 18 +++++++++++
 include/uapi/linux/userfaultfd.h |  3 ++
 ipc/shm.c                        |  6 ++--
 mm/mmap.c                        | 46 ++++++++++++++++++----------
 mm/mremap.c                      | 23 ++++++++------
 mm/util.c                        |  5 +++-
 14 files changed, 155 insertions(+), 41 deletions(-)

diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
index f9dbfb1..093517e 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 6225cc9..8899018 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 10820f6..572cee3 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 aad4ac3..c980796 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 873b4ca..7e2ab9c 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 5105b15..42e5666 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 e9b4a50..651d6d8 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 5e453ab..15e3f5d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h

@@ -2052,18 +2052,22 @@ 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 2521542..a40be5d 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 b742c40..3b05953 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 81203e8..cb0dfe9 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 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 			 */
 			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 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 		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;
 	}

diff --git a/mm/mmap.c b/mm/mmap.c
index f040ea0..563348c 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 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 	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 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 
 	/* 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 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 		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 @@ int vm_munmap(unsigned long start, size_t len)
 
 	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 @@ static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long
 	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 8779928..8233b01 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 @@ static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 	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 @@ static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 
 	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 @@ static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 	 * 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 @@ static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 		}
 
 		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 @@ static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 	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/util.c b/mm/util.c
index 3cb2164..b8f5388 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);
 	}

-- 
1.9.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

`h`	back out one level
`j`	next message in thread
`k`	previous message in thread
`l`	drill in
`Esc`	close help / fold thread tree
`?`	toggle this help