]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
mm/mprotect: use long for page accountings and retval
authorPeter Xu <peterx@redhat.com>
Wed, 4 Jan 2023 22:52:06 +0000 (17:52 -0500)
committerAndrew Morton <akpm@linux-foundation.org>
Thu, 19 Jan 2023 01:12:53 +0000 (17:12 -0800)
commita79390f5d6a78647fd70856bd42b22d994de0ba2
tree4b6528a12bf5bcab1ca80b47029b286f80268f0d
parent6b7cea90c82e104c1151fec1f3ee216997fda652
mm/mprotect: use long for page accountings and retval

Switch to use type "long" for page accountings and retval across the whole
procedure of change_protection().

The change should have shrinked the possible maximum page number to be
half comparing to previous (ULONG_MAX / 2), but it shouldn't overflow on
any system either because the maximum possible pages touched by change
protection should be ULONG_MAX / PAGE_SIZE.

Two reasons to switch from "unsigned long" to "long":

  1. It suites better on count_vm_numa_events(), whose 2nd parameter takes
     a long type.

  2. It paves way for returning negative (error) values in the future.

Currently the only caller that consumes this retval is change_prot_numa(),
where the unsigned long was converted to an int.  Since at it, touching up
the numa code to also take a long, so it'll avoid any possible overflow
too during the int-size convertion.

Link: https://lkml.kernel.org/r/20230104225207.1066932-3-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: James Houghton <jthoughton@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
include/linux/hugetlb.h
include/linux/mm.h
mm/hugetlb.c
mm/mempolicy.c
mm/mprotect.c