From 3ca7a9ba58541d8692d3f83cbded2ad17be23359 Mon Sep 17 00:00:00 2001
From: Huang Ying <ying.huang@intel.com>
Date: Mon, 20 Jul 2020 11:29:38 +0800
Subject: [PATCH] dbg: dump upon abnormal pte values

---
 mm/swap_state.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index 05889e8e3c97..c1973136d035 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -756,6 +756,17 @@ static struct page *swap_vma_readahead(swp_entry_t fentry, gfp_t gfp_mask,
 	blk_start_plug(&plug);
 	for (i = 0, pte = ra_info.ptes; i < ra_info.nr_pte;
 	     i++, pte++) {
+		pte_t *tpte = pte_offset_map(vmf->pmd, vmf->address);
+
+		if (((unsigned long)pte >> PAGE_SHIFT) !=
+		    ((unsigned long)tpte >> PAGE_SHIFT)) {
+			pr_info("ra_info: %d, %d, %d, %p\n",
+				ra_info.win, ra_info.offset, ra_info.nr_pte,
+				ra_info.ptes);
+			pr_info("i: %d, pte: %p, faddr: %lx\n", i, pte,
+				vmf->address);
+		}
+		pte_unmap(tpte);
 		pentry = *pte;
 		if (pte_none(pentry))
 			continue;
-- 
2.27.0