mm/madvise: split out madvise input validity check

Split out the madvise parameters validation logic from do_madvise(), for
easy reuse of the logic from a future change.

Link: https://lkml.kernel.org/r/20250206061517.2958-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Liam R. Howlett <howlett@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/madvise.c b/mm/madvise.c
index fa5dae5a77230f4656a46d868b2f88a62d7158bc..ca858b8a837b34efdb871bc30e0f1b495c840899 100644 (file)
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1618,6 +1618,27 @@ static void madvise_unlock(struct mm_struct *mm, int behavior)
                mmap_read_unlock(mm);
 }
 
+static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior)
+{
+       size_t len;
+
+       if (!madvise_behavior_valid(behavior))
+               return false;
+
+       if (!PAGE_ALIGNED(start))
+               return false;
+       len = PAGE_ALIGN(len_in);
+
+       /* Check to see whether len was rounded up from small -ve to zero */
+       if (len_in && !len)
+               return false;
+
+       if (start + len < start)
+               return false;
+
+       return true;
+}
+
 /*
  * The madvise(2) system call.
  *
@@ -1697,20 +1718,11 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
        size_t len;
        struct blk_plug plug;
 
-       if (!madvise_behavior_valid(behavior))
+       if (!is_valid_madvise(start, len_in, behavior))
                return -EINVAL;
 
-       if (!PAGE_ALIGNED(start))
-               return -EINVAL;
        len = PAGE_ALIGN(len_in);
-
-       /* Check to see whether len was rounded up from small -ve to zero */
-       if (len_in && !len)
-               return -EINVAL;
-
        end = start + len;
-       if (end < start)
-               return -EINVAL;
 
        if (end == start)
                return 0;