mm/shm: Convert bytes to pages by MM_NPAGES instead of MM_PGALIGNUP

mm/shm/shmat.c

@@ -153,7 +153,7 @@ FAR void *shmat(int shmid, FAR const void *shmaddr, int shmflg)
 
   /* Convert the region size to pages */
 
-  npages = MM_PGALIGNUP(region->sr_ds.shm_segsz);
+  npages = MM_NPAGES(region->sr_ds.shm_segsz);
 
   /* Attach, i.e, map, on shared memory region to the user virtual address. */
 

mm/shm/shmdt.c

@@ -132,7 +132,7 @@ int shmdt(FAR const void *shmaddr)
 
   /* Convert the region size to pages */
 
-  npages = MM_PGALIGNUP(region->sr_ds.shm_segsz);
+  npages = MM_NPAGES(region->sr_ds.shm_segsz);
 
   /* Detach, i.e, unmap, on shared memory region from a user virtual
    * address.

mm/shm/shmget.c

@@ -173,11 +173,11 @@ static int shm_extend(int shmid, size_t size)
 
   /* This is the number of pages that are needed to satisfy the allocation */
 
-  pgneeded = MM_PGALIGNUP(size);
+  pgneeded = MM_NPAGES(size);
 
   /* This is the number of pages that have already been allocated */
 
-  pgalloc = MM_PGALIGNUP(region->sr_ds.shm_segsz);
+  pgalloc = MM_NPAGES(region->sr_ds.shm_segsz);
 
   /* Loop until all pages have been allocated (or something bad happens) */
 
@@ -192,7 +192,7 @@ static int shm_extend(int shmid, size_t size)
           break;
         }
 
-      /* Increment the number of pages successully allocated */
+      /* Increment the number of pages successfully allocated */
 
       pgalloc++;
     }