Re: [PATCH v2] alloc_tag: check mem_profiling_support in alloc_tag_init

[Suren Baghdasaryan <surenb@google.com>]

On Fri, May 9, 2025 at 4:11 PM Suren Baghdasaryan <surenb@google.com> wrote:
>
> On Thu, May 8, 2025 at 4:47 PM Casey Chen <cachen@purestorage.com> wrote:
> >
> > Allocate module tags and register codetag type only when
> > mem_profiling_support is true. If it is set as false,
> > for example by sysctl.vm.mem_profiling=never, skip them.
> >
> > Signed-off-by: Casey Chen <cachen@purestorage.com>
> > Reviewed-by: Yuanyuan Zhong <yzhong@purestorage.com>
>
> Thanks! Looks good to me but let me take a closer look over the
> weekend to make sure we do not break anything by skipping this
> allocation.

I tested the patch and it works as expected. One thing I noticed is
the extra mem_profiling_support check inside procfs_init(). Please
move procfs_init() call into the "if (mem_profiling_support)" block
you added and remove the extra mem_profiling_support check from
procfs_init(). Actually, since procfs_init() becomes just one call
after the extra check removal, I would suggest just moving the
proc_create_seq() into alloc_tag_init() directly and eliminating the
procfs_init() function completely.

>
> > ---
> >  lib/alloc_tag.c | 18 ++++++++++--------
> >  1 file changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> > index 25ecc1334b67..fbf128072c7e 100644
> > --- a/lib/alloc_tag.c
> > +++ b/lib/alloc_tag.c
> > @@ -762,14 +762,16 @@ static int __init alloc_tag_init(void)
> >         };
> >         int res;
> >
> > -       res = alloc_mod_tags_mem();
> > -       if (res)
> > -               return res;
> > -
> > -       alloc_tag_cttype = codetag_register_type(&desc);
> > -       if (IS_ERR(alloc_tag_cttype)) {
> > -               free_mod_tags_mem();
> > -               return PTR_ERR(alloc_tag_cttype);
> > +       if (mem_profiling_support) {
> > +               res = alloc_mod_tags_mem();
> > +               if (res)
> > +                       return res;
> > +
> > +               alloc_tag_cttype = codetag_register_type(&desc);
> > +               if (IS_ERR(alloc_tag_cttype)) {
> > +                       free_mod_tags_mem();
> > +                       return PTR_ERR(alloc_tag_cttype);
> > +               }
> >         }
> >
> >         sysctl_init();
> > --
> > 2.49.0
> >