[PATCH] mm: fallback to next_order if charing mTHP fails

[Barry Song]

When memcg approaches its limit, charging mTHP becomes difficult.
At this point, when the charge fails, we fallback to the next order
to avoid repeatedly retrying larger orders.

Reported-by: Kairui Song <ryncsn@xxxxxxxxx>
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
---
 mm/memory.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 0ed3603aaf31..6cba28ef91e7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4121,8 +4121,12 @@ static struct folio *alloc_swap_folio(struct vm_fault *vmf)
 	while (orders) {
 		addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
 		folio = vma_alloc_folio(gfp, order, vma, addr, true);
-		if (folio)
-			return folio;
+		if (folio) {
+			if (!mem_cgroup_swapin_charge_folio(folio,
+					vma->vm_mm, gfp, entry))
+				return folio;
+			folio_put(folio);
+		}
 		order = next_order(&orders, order);
 	}
 
@@ -4244,7 +4248,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 				}
 				need_clear_cache = true;
 
-				if (mem_cgroup_swapin_charge_folio(folio,
+				if (nr_pages == 1 && mem_cgroup_swapin_charge_folio(folio,
 							vma->vm_mm, GFP_KERNEL,
 							entry)) {
 					ret = VM_FAULT_OOM;
-- 
2.34.1


Thanks
Barry