On Wed, Apr 10, 2024 at 02:34:35PM +0200, David Hildenbrand wrote:
> On 09.04.24 17:54, Sumanth Korikkar wrote:
> > In order to minimize code size (CONFIG_CC_OPTIMIZE_FOR_SIZE=y),
> > compiler might choose to make a regular function call (out-of-line) for
> > shmem_is_huge() instead of inlining it. When transparent hugepages are
> > disabled (CONFIG_TRANSPARENT_HUGEPAGE=n), it can cause compilation
> > error.
> >
> > mm/shmem.c: In function ‘shmem_getattr’:
> > ./include/linux/huge_mm.h:383:27: note: in expansion of macro ‘BUILD_BUG’
> > 383 | #define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })
> > | ^~~~~~~~~
> > mm/shmem.c:1148:33: note: in expansion of macro ‘HPAGE_PMD_SIZE’
> > 1148 | stat->blksize = HPAGE_PMD_SIZE;
> >
> > To prevent the possible error, always inline shmem_is_huge() when
> > transparent hugepages are disabled.
> >
>
> Do you know which commit introduced that?
Hi David,
Currently with CONFIG_CC_OPTIMIZE_FOR_SIZE=y and expirementing with
-fPIC kernel compiler option, I could see this error on s390.
However, default kernel compiler options doesnt end up with the above
pattern right now.
I think, shmem_is_huge() for disabled transparent hugepages comes from:
Commit 5e6e5a12a44c ("huge tmpfs: shmem_is_huge(vma, inode, index)")
However, HPAGE_PMD_SIZE macros for !CONFIG_TRANSPARENT_HUGEPAGE
originates from:
Commit d8c37c480678 ("thp: add HPAGE_PMD_* definitions for
!CONFIG_TRANSPARENT_HUGEPAGE")
Thanks,
Sumanth
