On 2025/9/11 10:28, Zi Yan wrote:
On 10 Sep 2025, at 22:12, Lance Yang wrote:
Hi Yafang,
On 2025/9/11 01:27, kernel test robot wrote:
Hi Yafang,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Yafang-Shao/mm-thp-remove-disabled-task-from-khugepaged_mm_slot/20250910-144850
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20250910024447.64788-2-laoar.shao%40gmail.com
patch subject: [PATCH v7 mm-new 01/10] mm: thp: remove disabled task from khugepaged_mm_slot
config: x86_64-allnoconfig (https://download.01.org/0day-ci/archive/20250911/202509110109.PSgSHb31-lkp@xxxxxxxxx/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250911/202509110109.PSgSHb31-lkp@xxxxxxxxx/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509110109.PSgSHb31-lkp@xxxxxxxxx/
All errors (new ones prefixed by >>):
kernel/sys.c:2500:6: error: call to undeclared function 'hugepage_pmd_enabled'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
2500 | hugepage_pmd_enabled())
| ^
kernel/sys.c:2501:3: error: call to undeclared function '__khugepaged_enter'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
2501 | __khugepaged_enter(mm);
| ^
2 errors generated.
Oops, seems like hugepage_pmd_enabled() and __khugepaged_enter() are only
available when CONFIG_TRANSPARENT_HUGEPAGE is enabled ;)
vim +/hugepage_pmd_enabled +2500 kernel/sys.c
2471
2472 static int prctl_set_thp_disable(bool thp_disable, unsigned long flags,
2473 unsigned long arg4, unsigned long arg5)
2474 {
2475 struct mm_struct *mm = current->mm;
2476
2477 if (arg4 || arg5)
2478 return -EINVAL;
2479
2480 /* Flags are only allowed when disabling. */
2481 if ((!thp_disable && flags) || (flags & ~PR_THP_DISABLE_EXCEPT_ADVISED))
2482 return -EINVAL;
2483 if (mmap_write_lock_killable(current->mm))
2484 return -EINTR;
2485 if (thp_disable) {
2486 if (flags & PR_THP_DISABLE_EXCEPT_ADVISED) {
2487 mm_flags_clear(MMF_DISABLE_THP_COMPLETELY, mm);
2488 mm_flags_set(MMF_DISABLE_THP_EXCEPT_ADVISED, mm);
2489 } else {
2490 mm_flags_set(MMF_DISABLE_THP_COMPLETELY, mm);
2491 mm_flags_clear(MMF_DISABLE_THP_EXCEPT_ADVISED, mm);
2492 }
2493 } else {
2494 mm_flags_clear(MMF_DISABLE_THP_COMPLETELY, mm);
2495 mm_flags_clear(MMF_DISABLE_THP_EXCEPT_ADVISED, mm);
2496 }
2497
2498 if (!mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm) &&
2499 !mm_flags_test(MMF_VM_HUGEPAGE, mm) &&
2500 hugepage_pmd_enabled())
2501 __khugepaged_enter(mm);
2502 mmap_write_unlock(current->mm);
2503 return 0;
2504 }
2505
So, let's wrap the new logic in an #ifdef CONFIG_TRANSPARENT_HUGEPAGE block.
diff --git a/kernel/sys.c b/kernel/sys.c
index a1c1e8007f2d..c8600e017933 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2495,10 +2495,13 @@ static int prctl_set_thp_disable(bool thp_disable, unsigned long flags,
mm_flags_clear(MMF_DISABLE_THP_EXCEPT_ADVISED, mm);
}
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
if (!mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm) &&
!mm_flags_test(MMF_VM_HUGEPAGE, mm) &&
hugepage_pmd_enabled())
__khugepaged_enter(mm);
+#endif
+
mmap_write_unlock(current->mm);
return 0;
}
Or in the header file,
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
...
#else
bool hugepage_pmd_enabled()
{
return false;
}
int __khugepaged_enter(struct mm_struct *mm)
{
return 0;
}
#endif
Nice. That's a much better approach.
