ksm: mremap use err from ksm_madvise

mremap move's use of ksm_madvise() was assuming -ENOMEM on failure,
because ksm_madvise used to say -EAGAIN for that; but ksm_madvise now says
-ENOMEM (letting madvise convert that to -EAGAIN), and can also say
-ERESTARTSYS when signalled: so pass the error from ksm_madvise.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/mm/mremap.c b/mm/mremap.c
index 93adddecf978..20a07dba6be0 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -175,6 +175,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
         unsigned long excess = 0;
         unsigned long hiwater_vm;
         int split = 0;
+        int err;
 
         /*
          * We'd prefer to avoid failure later on in do_munmap:
@@ -190,9 +191,10 @@ static unsigned long move_vma(struct vm_area_struct *vma,
          * pages recently unmapped.  But leave vma->vm_flags as it was,
          * so KSM can come around to merge on vma and new_vma afterwards.
          */
-        if (ksm_madvise(vma, old_addr, old_addr + old_len,
-                                                MADV_UNMERGEABLE, &vm_flags))
-                return -ENOMEM;
+        err = ksm_madvise(vma, old_addr, old_addr + old_len,
+                                                MADV_UNMERGEABLE, &vm_flags);
+        if (err)
+                return err;
 
         new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT);
         new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff);