linux-kernel - Re: [PATCH] [v2] alloc_tag: hide execmem

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Message-ID: <CAJuCfpFyERAN40UAsKqugODBX=G+s+87w0LiBgWP2nUqdboh3g@mail.gmail.com>
Date: Mon, 28 Oct 2024 13:31:19 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Pasha Tatashin <pasha.tatashin@...een.com>, 
	Arnd Bergmann <arnd@...db.de>, Mike Rapoport <rppt@...nel.org>, Luis Chamberlain <mcgrof@...nel.org>, 
	Song Liu <song@...nel.org>, "Masami Hiramatsu (Google)" <mhiramat@...nel.org>, linux-mm@...ck.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [v2] alloc_tag: hide execmem_vmap() on !MMU

On Mon, Oct 28, 2024 at 11:53 AM Suren Baghdasaryan <surenb@...gle.com> wrote:
>
> On Mon, Oct 28, 2024 at 8:04 AM Arnd Bergmann <arnd@...nel.org> wrote:
> >
> > From: Arnd Bergmann <arnd@...db.de>
> >
> > The newly added function fails to link on nommu kernels, but is also
> > not needed there:
> >
> > ld.lld-20: error: undefined symbol: __get_vm_area_node
> > >>> referenced by execmem.c
> > >>>               mm/execmem.o:(execmem_vmap) in archive vmlinux.a
> > >>> referenced by execmem.c
> > >>>               mm/execmem.o:(execmem_vmap) in archive vmlinux.a
> >
> > Move it into the #ifdef block along with execmem_vmalloc().
> >
> > Fixes: 57bc3834fb6f ("alloc_tag: populate memory for module tags as needed")
> > Acked-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> > Signed-off-by: Arnd Bergmann <arnd@...db.de>
>
> Sorry, replied to your older version. Copying here:
>
> Thanks for the fix but execmem_vmap() is used if
> CONFIG_MEM_ALLOC_PROFILING=y. Please give me an hour to post a fix
> dealing with that.

The fix that will work with CONFIG_MEM_ALLOC_PROFILING is posted at
https://lore.kernel.org/all/20241028202935.1047017-1-surenb@google.com/

>
> > ---
> >  mm/execmem.c | 32 ++++++++++++++++----------------
> >  1 file changed, 16 insertions(+), 16 deletions(-)
> >
> > diff --git a/mm/execmem.c b/mm/execmem.c
> > index 5c0f9f2d6f83..317b6a8d35be 100644
> > --- a/mm/execmem.c
> > +++ b/mm/execmem.c
> > @@ -64,6 +64,22 @@ static void *execmem_vmalloc(struct execmem_range *range, size_t size,
> >
> >         return p;
> >  }
> > +
> > +struct vm_struct *execmem_vmap(size_t size)
> > +{
> > +       struct execmem_range *range = &execmem_info->ranges[EXECMEM_MODULE_DATA];
> > +       struct vm_struct *area;
> > +
> > +       area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > +                                 range->start, range->end, NUMA_NO_NODE,
> > +                                 GFP_KERNEL, __builtin_return_address(0));
> > +       if (!area && range->fallback_start)
> > +               area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > +                                         range->fallback_start, range->fallback_end,
> > +                                         NUMA_NO_NODE, GFP_KERNEL, __builtin_return_address(0));
> > +
> > +       return area;
> > +}
> >  #else
> >  static void *execmem_vmalloc(struct execmem_range *range, size_t size,
> >                              pgprot_t pgprot, unsigned long vm_flags)
> > @@ -368,22 +384,6 @@ void execmem_free(void *ptr)
> >                 vfree(ptr);
> >  }
> >
> > -struct vm_struct *execmem_vmap(size_t size)
> > -{
> > -       struct execmem_range *range = &execmem_info->ranges[EXECMEM_MODULE_DATA];
> > -       struct vm_struct *area;
> > -
> > -       area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > -                                 range->start, range->end, NUMA_NO_NODE,
> > -                                 GFP_KERNEL, __builtin_return_address(0));
> > -       if (!area && range->fallback_start)
> > -               area = __get_vm_area_node(size, range->alignment, PAGE_SHIFT, VM_ALLOC,
> > -                                         range->fallback_start, range->fallback_end,
> > -                                         NUMA_NO_NODE, GFP_KERNEL, __builtin_return_address(0));
> > -
> > -       return area;
> > -}
> > -
> >  void *execmem_update_copy(void *dst, const void *src, size_t size)
> >  {
> >         return text_poke_copy(dst, src, size);
> > --
> > 2.39.5
> >