userfaultfd: add VM_UFFD_MISSING and VM_UFFD_WP

Orabug: 21685254

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>
(cherry picked from commit 16ba6f811dfe44bc14f7946a4b257b85476fc16e)
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Dhaval Giani <dhaval.giani@oracle.com>
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 32287fb146db44c83d950dcc4d5b9bdcc959b771..9ed35c875024fea3b2c74c5def0c5ce2ad54a740 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 d6b51401028ecfb647846ce8581b7a53bd3c957b..7ad57105b8f289867a6204bb5eedddc6a0783c46 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -123,8 +123,10 @@ 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 ba3ef50774558a436562ec96ab220d9d6873a566..6f285a9af2cd6b16b0eff3419c184c546d2f1629 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -449,7 +449,7 @@ 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;