The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 348923665a0e50ad9fc0b3bb8127d3cb976691cc Mon Sep 17 00:00:00 2001
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Date: Tue, 22 Mar 2022 14:42:02 -0700
Subject: [PATCH] mm: hugetlb: fix missing cache flush in
hugetlb_mcopy_atomic_pte()
folio_copy() will copy the data from one page to the target page, then
the target page will be mapped to the user space address, which might
have an alias issue with the kernel address used to copy the data from
the page to. There are 2 ways to fix this issue.
1) insert flush_dcache_page() after folio_copy().
2) replace folio_copy() with copy_user_huge_page() which already
considers the cache maintenance.
We chose 2) way to fix the issue since architectures can optimize this
situation. It is also make backports easier.
Link: https://lkml.kernel.org/r/20220210123058.79206-5-songmuchun@xxxxxxxxxxxxx
Fixes: 8cc5fcbb5be8 ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY")
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Fam Zheng <fam.zheng@xxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lars Persson <lars.persson@xxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a404af0b49a0..3d450f802823 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5816,7 +5816,8 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
*pagep = NULL;
goto out;
}
- folio_copy(page_folio(page), page_folio(*pagep));
+ copy_user_huge_page(page, *pagep, dst_addr, dst_vma,
+ pages_per_huge_page(h));
put_page(*pagep);
*pagep = NULL;
}
