[PATCH v3 22/22] mm/mshare: charge fault handling allocations to the mshare owner

[Anthony Yznaga]

When handling a fault in an mshare range, redirect charges for page
tables and other allocations to the mshare owner rather than the
current task.

Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
---
 mm/memory.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index 177eb53475cb..127db0b9932c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6468,9 +6468,17 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
 	struct mm_struct *mm = vma->vm_mm;
 	vm_fault_t ret;
 	bool is_droppable;
+	bool is_mshare = mm_flags_test(MMF_MSHARE, mm);
+	struct mem_cgroup *mshare_memcg;
+	struct mem_cgroup *memcg;
 
 	__set_current_state(TASK_RUNNING);
 
+	if (unlikely(is_mshare)) {
+		mshare_memcg = get_mem_cgroup_from_mm(vma->vm_mm);
+		memcg = set_active_memcg(mshare_memcg);
+	}
+
 	ret = sanitize_fault_flags(vma, &flags);
 	if (ret)
 		goto out;
@@ -6530,6 +6538,11 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
 out:
 	mm_account_fault(mm, regs, address, flags, ret);
 
+	if (unlikely(is_mshare)) {
+		set_active_memcg(memcg);
+		mem_cgroup_put(mshare_memcg);
+	}
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(handle_mm_fault);
-- 
2.47.1