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Message-ID: <20170205184629.GA28665@roeck-us.net>
Date: Sun, 5 Feb 2017 10:46:29 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Mike Rapoport <rppt@...ux.vnet.ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
"Dr. David Alan Gilbert" <dgilbert@...hat.com>,
Hillf Danton <hillf.zj@...baba-inc.com>,
Mike Kravetz <mike.kravetz@...cle.com>,
Pavel Emelyanov <xemul@...tuozzo.com>,
Linux-MM <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [v2,2/5] userfaultfd: non-cooperative: add event for memory
unmaps
On Fri, Jan 27, 2017 at 08:44:30PM +0200, Mike Rapoport wrote:
> 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 <rppt@...ux.vnet.ibm.com>
> Acked-by: Hillf Danton <hillf.zj@...baba-inc.com>
Just in case 0day didn't report it yet, this patch causes build errors
with various architectures.
mm/nommu.c:1201:15: error: conflicting types for 'do_mmap'
unsigned long do_mmap(struct file *file,
^
In file included from mm/nommu.c:19:0:
include/linux/mm.h:2095:22: note:
previous declaration of 'do_mmap' was here
mm/nommu.c:1580:5: error: conflicting types for 'do_munmap'
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
^
In file included from mm/nommu.c:19:0:
include/linux/mm.h:2099:12: note:
previous declaration of 'do_munmap' was here
Guenter
> ---
> 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@...p.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);
> }
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