linux-kernel - Re: [PATCH v2 2/2] alloc_tag: outline and export free_reserved

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Message-ID: <CAJuCfpG2uNicytRYhfqAKrfkxJoNLUUK_o066D=yKggsoc3wKQ@mail.gmail.com>
Date: Wed, 17 Jul 2024 13:04:57 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: akpm@...ux-foundation.org, kent.overstreet@...ux.dev, hch@...radead.org, 
	pasha.tatashin@...een.com, souravpanda@...gle.com, keescook@...omium.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v2 2/2] alloc_tag: outline and export free_reserved_page()

On Wed, Jul 17, 2024 at 12:36 PM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> On 7/17/24 8:12 PM, Suren Baghdasaryan wrote:
> > Outline and export free_reserved_page() because modules use it and it
> > in turn uses page_ext_{get|put} which should not be exported. The same
> > result could be obtained by outlining {get|put}_page_tag_ref() but that
> > would have higher performance impact as these functions are used in
> > more performance critical paths.
> >
> > Fixes: dcfe378c81f7 ("lib: introduce support for page allocation tagging")
> > Reported-by: kernel test robot <lkp@...el.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202407080044.DWMC9N9I-lkp@intel.com/
> > Suggested-by: Christoph Hellwig <hch@...radead.org>
> > Suggested-by: Vlastimil Babka <vbabka@...e.cz>
> > Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
>
> Acked-by: Vlastimil Babka <vbabka@...e.cz>
>
> Are these two patches now stable@ material as 6.10 build is broken on ppc64
> with alloc taging enabled?

I tested them with that specific configuration mentioned in the bug
report and with several usual ones I use.
Yeah, I guess from now on all such fixes should have

Cc: stable@...r.kernel.org # v6.10

>
> > ---
> > Changes since v1 [1]
> > - Outlined and exported free_reserved_page() in place of {get|put}_page_tag_ref,
> > per Vlastimil Babka
> >
> > [1] https://lore.kernel.org/all/20240717011631.2150066-2-surenb@google.com/
> >
> >  include/linux/mm.h | 16 +---------------
> >  mm/page_alloc.c    | 17 +++++++++++++++++
> >  2 files changed, 18 insertions(+), 15 deletions(-)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index eb7c96d24ac0..b58bad248eef 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -3177,21 +3177,7 @@ extern void reserve_bootmem_region(phys_addr_t start,
> >                                  phys_addr_t end, int nid);
> >
> >  /* Free the reserved page into the buddy system, so it gets managed. */
> > -static inline void free_reserved_page(struct page *page)
> > -{
> > -     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);
> > -             }
> > -     }
> > -     ClearPageReserved(page);
> > -     init_page_count(page);
> > -     __free_page(page);
> > -     adjust_managed_page_count(page, 1);
> > -}
> > +void free_reserved_page(struct page *page);
> >  #define free_highmem_page(page) free_reserved_page(page)
> >
> >  static inline void mark_page_reserved(struct page *page)
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 9ecf99190ea2..7d2fa9f5e750 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -5805,6 +5805,23 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
> >       return pages;
> >  }
> >
> > +void free_reserved_page(struct page *page)
> > +{
> > +     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);
> > +             }
> > +     }
> > +     ClearPageReserved(page);
> > +     init_page_count(page);
> > +     __free_page(page);
> > +     adjust_managed_page_count(page, 1);
> > +}
> > +EXPORT_SYMBOL(free_reserved_page);
> > +
> >  static int page_alloc_cpu_dead(unsigned int cpu)
> >  {
> >       struct zone *zone;
>