The MADV_COLLAPSE will ignore the system-wide Anon THP sysfs settings, which
means that even though we have disabled the Anon THP configuration, MADV_COLLAPSE
will still attempt to collapse into a Anon THP. This violates the rule we have
agreed upon: never means never.
To address this issue, should check whether the Anon THP configuration is disabled
in thp_vma_allowable_orders(), even when the TVA_ENFORCE_SYSFS flag is set.
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
include/linux/huge_mm.h | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 2f190c90192d..199ddc9f04a1 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -287,20 +287,35 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
unsigned long orders)
{
/* Optimization to check if required orders are enabled early. */
- if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) {
- unsigned long mask = READ_ONCE(huge_anon_orders_always);
+ if (vma_is_anonymous(vma)) {
+ unsigned long always = READ_ONCE(huge_anon_orders_always);
+ unsigned long madvise = READ_ONCE(huge_anon_orders_madvise);
+ unsigned long inherit = READ_ONCE(huge_anon_orders_inherit);
+ unsigned long mask = always | madvise;
+
+ /*
+ * If the system-wide THP/mTHP sysfs settings are disabled,
+ * then we should never allow hugepages.
+ */
+ if (!(mask & orders) && !(hugepage_global_enabled() && (inherit & orders)))
+ return 0;
+
+ if (!(tva_flags & TVA_ENFORCE_SYSFS))
+ goto skip;
+ mask = always;
if (vm_flags & VM_HUGEPAGE)
- mask |= READ_ONCE(huge_anon_orders_madvise);
+ mask |= madvise;
if (hugepage_global_always() ||
((vm_flags & VM_HUGEPAGE) && hugepage_global_enabled()))
- mask |= READ_ONCE(huge_anon_orders_inherit);
+ mask |= inherit;
orders &= mask;
if (!orders)
return 0;
}
+skip:
return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders);
}
--
2.43.5
