[RFC PATCH v3 2/5] mm, thp: add bpf thp hook to determine thp allocator

[Yafang Shao <laoar.shao@gmail.com>]

A new hook bpf_thp_allocator() is added to determine if the THP is
allocated by khugepaged or by the current task.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 include/linux/huge_mm.h | 10 ++++++++++
 mm/khugepaged.c         |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 2f190c90192d..db2eadd3f65b 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -190,6 +190,14 @@ static inline bool hugepage_global_always(void)
 			(1<<TRANSPARENT_HUGEPAGE_FLAG);
 }
 
+#define THP_ALLOC_KHUGEPAGED (1 << 1)
+#define THP_ALLOC_CURRENT (1 << 2)
+static inline int bpf_thp_allocator(unsigned long vm_flags,
+				     unsigned long tva_flags)
+{
+	return THP_ALLOC_KHUGEPAGED | THP_ALLOC_CURRENT;
+}
+
 static inline int highest_order(unsigned long orders)
 {
 	return fls_long(orders) - 1;
@@ -290,6 +298,8 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
 	if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) {
 		unsigned long mask = READ_ONCE(huge_anon_orders_always);
 
+		if (!(bpf_thp_allocator(vm_flags, tva_flags) & THP_ALLOC_CURRENT))
+			return 0;
 		if (vm_flags & VM_HUGEPAGE)
 			mask |= READ_ONCE(huge_anon_orders_madvise);
 		if (hugepage_global_always() ||
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 79e208999ddb..18f800fe7335 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -472,6 +472,8 @@ void __khugepaged_enter(struct mm_struct *mm)
 void khugepaged_enter_vma(struct vm_area_struct *vma,
 			  unsigned long vm_flags)
 {
+	if (!(bpf_thp_allocator(vm_flags, 0) & THP_ALLOC_KHUGEPAGED))
+		return;
 	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&
 	    hugepage_pmd_enabled()) {
 		if (__thp_vma_allowable_orders(vma, vm_flags, TVA_ENFORCE_SYSFS,
-- 
2.43.5