Re: [-mm][PATCH 2/4] Setup the memrlimit controller (v5)

Andrew Morton
2008-06-11T19:16:13Z

On Wed, 11 Jun 2008 19:10:40 +0200 (MEST)
Andrea Righi <righi.andrea@gmail.com> wrote:

> Balbir Singh wrote:
> > +static int memrlimit_cgroup_write_strategy(char *buf, unsigned long long *tmp)
> > +{
> > + *tmp = memparse(buf, &buf);
> > + if (*buf != '\0')
> > + return -EINVAL;
> > +
> > + *tmp = PAGE_ALIGN(*tmp);
> > + return 0;
> > +}
>
> We shouldn't use PAGE_ALIGN() here, otherwise we limit the address space
> to 4GB on 32-bit architectures (that could be reasonable, because this
> is a per-cgroup limit and not per-process).
>
> Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
> ---
> mm/memrlimitcgroup.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/mm/memrlimitcgroup.c b/mm/memrlimitcgroup.c
> index 9a03d7d..2d42ff3 100644
> --- a/mm/memrlimitcgroup.c
> +++ b/mm/memrlimitcgroup.c
> @@ -29,6 +29,8 @@
> #include <linux/res_counter.h>
> #include <linux/memrlimitcgroup.h>
>
> +#define PAGE_ALIGN64(addr) (((((addr)+PAGE_SIZE-1))>>PAGE_SHIFT)<<PAGE_SHIFT)
> +
> struct cgroup_subsys memrlimit_cgroup_subsys;
>
> struct memrlimit_cgroup {
> @@ -124,7 +126,7 @@ static int memrlimit_cgroup_write_strategy(char *buf, unsigned long long *tmp)
> if (*buf != '\0')
> return -EINVAL;
>
> - *tmp = PAGE_ALIGN(*tmp);
> + *tmp = PAGE_ALIGN64(*tmp);
> return 0;
> }
>

I don't beleive the change is needed.

#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)

that implementation will behaved as desired when passed a 64-bit addr?