On Wed, Jan 4, 2023 at 10:52 PM Peter Xu <peterx@xxxxxxxxxx> wrote: > > 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. > > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> > --- > include/linux/hugetlb.h | 4 ++-- > include/linux/mm.h | 2 +- > mm/hugetlb.c | 4 ++-- > mm/mempolicy.c | 2 +- > mm/mprotect.c | 26 +++++++++++++------------- > 5 files changed, 19 insertions(+), 19 deletions(-) Acked-by: James Houghton <jthoughton@xxxxxxxxxx>
