On Wed, 20 May 2020 16:20:05 +0300 Mike Rapoport <rppt(a)linux.ibm.com> wrote:
The kbuild test robot reported the following warning:
arch/sparc/mm/srmmu.c: In function 'srmmu_nocache_init':
>> arch/sparc/mm/srmmu.c:300:9: error: variable 'pud' set but not used
>> [-Werror=unused-but-set-variable]
300 | pud_t *pud;
This warning is caused by misprint in the page table traversal in
srmmu_nocache_init() function which accessed a PMD entry using PGD rather
than PUD.
Since sparc32 has only 3 page table levels, the PGD and PUD are essentially
the same and usage of __nocache_fix() removed the type checking.
Use PUD for the consistency and to silence the compiler warning.
...
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -304,7 +304,7 @@ static void __init srmmu_nocache_init(void)
pgd = pgd_offset_k(vaddr);
p4d = p4d_offset(__nocache_fix(pgd), vaddr);
pud = pud_offset(__nocache_fix(p4d), vaddr);
- pmd = pmd_offset(__nocache_fix(pgd), vaddr);
+ pmd = pmd_offset(__nocache_fix(pud), vaddr);
pte = pte_offset_kernel(__nocache_fix(pmd), vaddr);
pteval = ((paddr >> 4) | SRMMU_ET_PTE | SRMMU_PRIV);
I added
Fixes: 7235db268a2777bc38 ("sparc32: use pgtable-nopud instead of
4level-fixup")
and, after a bit of thought,
Cc: <stable(a)vger.kernel.org>
Because that's a fairly scary-looking warning.