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Commit 897ab3e0 authored by Mike Rapoport's avatar Mike Rapoport Committed by Linus Torvalds
Browse files

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: default avatarMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarHillf 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 846b1a0f

arch/mips/kernel/vdso.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

arch/tile/mm/elf.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}

arch/x86/entry/vdso/vma.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

arch/x86/mm/mpx.c

+2 −2
Original line number Diff line number Diff line
@@ -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,

fs/aio.c

+1 −1
Original line number Diff line number Diff line
@@ -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;