userfaultfd: add VM_UFFD_MISSING and VM_UFFD_WP

These two flags gets set in vma->vm_flags to tell the VM common code
if the userfaultfd is armed and in which mode (only tracking missing
faults, only tracking wrprotect faults or both). If neither flags is
set it means the userfaultfd is not armed on the vma.

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/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index ca1e091..3b4d825 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -597,6 +597,8 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
                [ilog2(VM_HUGEPAGE)]    = "hg",
                [ilog2(VM_NOHUGEPAGE)]  = "nh",
                [ilog2(VM_MERGEABLE)]   = "mg",
+               [ilog2(VM_UFFD_MISSING)]= "um",
+               [ilog2(VM_UFFD_WP)]     = "uw",
        };
        size_t i;
 

diff --git a/include/linux/mm.h b/include/linux/mm.h
index bf6f117..0f7cd30 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -124,8 +124,10 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_MAYSHARE    0x00000080
 
 #define VM_GROWSDOWN   0x00000100      /* general info on the segment */
+#define VM_UFFD_MISSING        0x00000200      /* missing pages tracking */
 #define VM_PFNMAP      0x00000400      /* Page-ranges managed without "struct page", just pure PFN */
 #define VM_DENYWRITE   0x00000800      /* ETXTBSY on write attempts.. */
+#define VM_UFFD_WP     0x00001000      /* wrprotect pages tracking */
 
 #define VM_LOCKED      0x00002000
 #define VM_IO           0x00004000     /* Memory mapped I/O or similar */

diff --git a/kernel/fork.c b/kernel/fork.c
index ceb4eb4..7d5f0f1 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -454,7 +454,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
                tmp->vm_mm = mm;
                if (anon_vma_fork(tmp, mpnt))
                        goto fail_nomem_anon_vma_fork;
-               tmp->vm_flags &= ~VM_LOCKED;
+               tmp->vm_flags &= ~(VM_LOCKED|VM_UFFD_MISSING|VM_UFFD_WP);
                tmp->vm_next = tmp->vm_prev = NULL;
                tmp->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
                file = tmp->vm_file;