From: Peter Xu <peterx@redhat.com>
Date: Wed, 2 Jun 2021 03:52:49 +0000 (+1000)
Subject: mm/userfaultfd: fix a few thp pmd missing uffd-wp bit
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=02ccf21d624619b92ae696df1e207d4c0bdff3df;p=users%2Fjedix%2Flinux-maple.git

mm/userfaultfd: fix a few thp pmd missing uffd-wp bit

These include:

1. When remove migration pmd entry, should keep the uffd-wp bit from
   swap pte.  Note that we need to do this after setting write bit just in
   case we need to remove it.

2. When change huge pmd and convert write -> read migration entry,
   persist the same uffd-wp bit.

3. When convert pmd to swap entry, should drop the uffd-wp bit always.

Link: https://lkml.kernel.org/r/20210428225030.9708-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Wang Qing <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 3ed89479cf1b1..af3d2661e41e8 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -281,6 +281,8 @@ static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
 
 	if (pmd_swp_soft_dirty(pmd))
 		pmd = pmd_swp_clear_soft_dirty(pmd);
+	if (pmd_swp_uffd_wp(pmd))
+		pmd = pmd_swp_clear_uffd_wp(pmd);
 	arch_entry = __pmd_to_swp_entry(pmd);
 	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 0c86ad8f1b3d8..68c78f72380ca 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1831,6 +1831,8 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 			newpmd = swp_entry_to_pmd(entry);
 			if (pmd_swp_soft_dirty(*pmd))
 				newpmd = pmd_swp_mksoft_dirty(newpmd);
+			if (pmd_swp_uffd_wp(*pmd))
+				newpmd = pmd_swp_mkuffd_wp(newpmd);
 			set_pmd_at(mm, addr, pmd, newpmd);
 		}
 		goto unlock;
@@ -3255,6 +3257,8 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
 		pmde = pmd_mksoft_dirty(pmde);
 	if (is_writable_migration_entry(entry))
 		pmde = maybe_pmd_mkwrite(pmde, vma);
+	if (pmd_swp_uffd_wp(*pvmw->pmd))
+		pmde = pmd_wrprotect(pmd_mkuffd_wp(pmde));
 
 	flush_cache_range(vma, mmun_start, mmun_start + HPAGE_PMD_SIZE);
 	if (PageAnon(new))