linux-kernel - Re: [PATCH v2 1/1] alloc_tag: mark pages reserved during CMA activation as not tagged

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Message-ID: <CAJuCfpGp_EJQ2xA5s0nj5qt6HA69G91+xpC7rTKZ5QE2fVr1ig@mail.gmail.com>
Date: Tue, 13 Aug 2024 08:18:25 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: David Hildenbrand <david@...hat.com>
Cc: akpm@...ux-foundation.org, kent.overstreet@...ux.dev, vbabka@...e.cz, 
	pasha.tatashin@...een.com, souravpanda@...gle.com, keescook@...omium.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, stable@...r.kernel.org
Subject: Re: [PATCH v2 1/1] alloc_tag: mark pages reserved during CMA
 activation as not tagged

On Tue, Aug 13, 2024 at 7:27 AM Suren Baghdasaryan <surenb@...gle.com> wrote:
>
> On Tue, Aug 13, 2024 at 2:25 AM David Hildenbrand <david@...hat.com> wrote:
> >
> > On 12.08.24 21:24, Suren Baghdasaryan wrote:
> > > During CMA activation, pages in CMA area are prepared and then freed
> > > without being allocated. This triggers warnings when memory allocation
> > > debug config (CONFIG_MEM_ALLOC_PROFILING_DEBUG) is enabled. Fix this
> > > by marking these pages not tagged before freeing them.
> > >
> > > Fixes: d224eb0287fb ("codetag: debug: mark codetags for reserved pages as empty")
> > > Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> > > Cc: stable@...r.kernel.org # v6.10
> > > ---
> > > changes since v1 [1]
> > > - Added Fixes tag
> > > - CC'ed stable
> > >
> > > [1] https://lore.kernel.org/all/20240812184455.86580-1-surenb@google.com/
> > >
> > >   mm/mm_init.c | 10 ++++++++++
> > >   1 file changed, 10 insertions(+)
> > >
> > > diff --git a/mm/mm_init.c b/mm/mm_init.c
> > > index 75c3bd42799b..ec9324653ad9 100644
> > > --- a/mm/mm_init.c
> > > +++ b/mm/mm_init.c
> > > @@ -2245,6 +2245,16 @@ void __init init_cma_reserved_pageblock(struct page *page)
> > >
> > >       set_pageblock_migratetype(page, MIGRATE_CMA);
> > >       set_page_refcounted(page);
> > > +
> > > +     /* pages were reserved and not allocated */
> > > +     if (mem_alloc_profiling_enabled()) {
> > > +             union codetag_ref *ref = get_page_tag_ref(page);
> > > +
> > > +             if (ref) {
> > > +                     set_codetag_empty(ref);
> > > +                     put_page_tag_ref(ref);
> > > +             }
> > > +     }
> >
> > Should we have a helper like clear_page_tag_ref() that wraps this?
>
> With this one we have 3 instances of this sequence, so it makes sense
> to have a helper. I'm going to send a v3 with 2 patches - one
> introducing clear_page_tag_ref() and the next one adding this
> instance.
> Thanks for the suggestion, David!

v3 posted at https://lore.kernel.org/all/20240813150758.855881-1-surenb@google.com/

>
> >
> > --
> > Cheers,
> >
> > David / dhildenb
> >