Re: [PATCH mk-II 08/17] asm-generic/tlb: Provide MMU_GATHER_TABLE_FREE

[Aneesh Kumar K.V]

On 1/27/20 1:41 PM, Peter Zijlstra wrote:
> On Sun, Jan 26, 2020 at 07:52:05AM -0800, Guenter Roeck wrote:
> > On Thu, Dec 12, 2019 at 10:32:05AM +0100, Peter Zijlstra wrote:
> > > As described in the comment, the correct order for freeing pages is:
> > >
> > >   1) unhook page
> > >   2) TLB invalidate page
> > >   3) free page
> > >
> > > This order equally applies to page directories.
> > >
> > > Currently there are two correct options:
> > >
> > >   - use tlb_remove_page(), when all page directores are full pages and
> > >     there are no futher contraints placed by things like software
> > >     walkers (HAVE_FAST_GUP).
> > >
> > >   - use MMU_GATHER_RCU_TABLE_FREE and tlb_remove_table() when the
> > >     architecture does not do IPI based TLB invalidate and has
> > >     HAVE_FAST_GUP (or software TLB fill).
> > >
> > > This however leaves architectures that don't have page based
> > > directories but don't need RCU in a bind. For those, provide
> > > MMU_GATHER_TABLE_FREE, which provides the independent batching for
> > > directories without the additional RCU freeing.
> > >
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > ---
> >
> > Various sparc64 builds (allnoconfig, tinyconfig, as well as builds
> > with SMP disabled):
> >
> > mm/mmu_gather.c: In function '__tlb_remove_table_free':
> > mm/mmu_gather.c:101:3: error: implicit declaration of function '__tlb_remove_table'; did you mean 'tlb_remove_table'?
>
> Thanks; I'll respin these patches against Aneesh' pile and make sure to
> look into this when I do so.

I did send a change to fix that. it is to drop !SMP change in the patch

https://lore.kernel.org/linux-mm/87v9p9mhnr.fsf@xxxxxxxxxxxxx


-aneesh