From 7528c4fb1237512ee18049f852f014eba80bbe8d Mon Sep 17 00:00:00 2001
From: Liu Shixin <liushixin2@huawei.com>
Date: Tue, 15 Oct 2024 09:45:21 +0800
Subject: [PATCH] mm/swapfile: skip HugeTLB pages for unuse_vma
I got a bad pud error and lost a 1GB HugeTLB when calling swapoff. The
problem can be reproduced by the following steps:
1. Allocate an anonymous 1GB HugeTLB and some other anonymous memory.
2. Swapout the above anonymous memory.
3. run swapoff and we will get a bad pud error in kernel message:
mm/pgtable-generic.c:42: bad pud 00000000743d215d(84000001400000e7)
We can tell that pud_clear_bad is called by pud_none_or_clear_bad in
unuse_pud_range() by ftrace. And therefore the HugeTLB pages will never
be freed because we lost it from page table. We can skip HugeTLB pages
for unuse_vma to fix it.
Link: https://lkml.kernel.org/r/20241015014521.570237-1-liushixin2@huawei.com
Fixes: 0fe6e20b9c4c ("hugetlb, rmap: add reverse mapping for hugepage")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Acked-by: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/swapfile.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index eb782fcd56270..b0915f3fab315 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2313,7 +2313,7 @@ static int unuse_mm(struct mm_struct *mm, unsigned int type)
mmap_read_lock(mm);
for_each_vma(vmi, vma) {
- if (vma->anon_vma) {
+ if (vma->anon_vma && !is_vm_hugetlb_page(vma)) {
ret = unuse_vma(vma, type);
if (ret)
break;
--
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