Re: Build error due to commit 458aa76d132dc ("mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range")

[Guenter Roeck]

On 03/21/2016 10:14 PM, Aneesh Kumar K.V wrote:
> Guenter Roeck <linux@xxxxxxxxxxxx> writes:
>
> > [ text/plain ]
> > Hi,
> >
> > Your commit 458aa76d132dc1 ("mm/thp/migration: switch from flush_tlb_range
> > to flush_pmd_tlb_range") causes a build error when building
> > arcv2:vdk_hs38_smp_defconfig.
> >
> > include/asm-generic/pgtable.h:799:45: note: in expansion of macro âBUILD_BUGâ
> >   #define flush_pmd_tlb_range(vma, addr, end) BUILD_BUG()
> >                                                ^
> > ./arch/arc/include/asm/tlbflush.h:37:13: note:
> > 	in expansion of macro âflush_pmd_tlb_rangeâ
> >
> > The build triggers the newly introduced BUILD_BUG().
> >
> > When building the image without the BUILD_BUG(), ie with no definition
> > of flush_pmd_tlb_range(), the problem is gone. This suggests that the
> > function is not needed for this build.
> >
> > I could submit a patch to remove the BUILD_BUG(), but maybe you had a reason
> > for introducing it. Can you elaborate why you introduced the BUILD_BUG() ?
>
> Isn't this going to be fixed by an update to ARC tree ?
>
> http://article.gmane.org/gmane.linux.kernel.mm/148412

That wasn't a build error ?

> I also don't understand why we would hit that BUILD_BUG, if we are not
> calling flush_pmd_tlb_range().
Good question.

I'll wait for the commit window to close and report again if needed.

Guenter