Re: [PATCH] mm/hugetlb: Fix build failure with HUGETLB_PAGE but not HUGEBTLBFS

On 3/17/20 1:04 AM, Christophe Leroy wrote:

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

In file included from arch/powerpc/mm/fault.c:33:0:
./include/linux/hugetlb.h: In function 'hstate_inode':
./include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
  return HUGETLBFS_SB(i->i_sb)->hstate;
         ^
./include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
  return HUGETLBFS_SB(i->i_sb)->hstate;
                              ^

Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.

Reported-by: kbuild test robot <redacted>
Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <redacted>

As hugetlb.h evolved over time, I suspect nobody imagined a configuration
with CONFIG_HUGETLB_PAGE and not CONFIG_HUGETLBFS.  This patch does address
the build issues.  So,

Reviewed-by: Mike Kravetz <redacted>

However, there are many definitions in that file not behind #ifdef
CONFIG_HUGETLBFS that make no sense unless CONFIG_HUGETLBFS is defined.
Such cleanup is way beyond the scope of this patch/effort.  I will add
it to the list of hugetlb/hugetlbfs things that can be cleaned up.
-- 
Mike Kravetz