6.6-stable review patch. If anyone has any objections, please let me know.
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From: Liu Shixin liushixin2@huawei.com
commit 7528c4fb1237512ee18049f852f014eba80bbe8d upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/swapfile.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2003,7 +2003,7 @@ static int unuse_mm(struct mm_struct *mm
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;