From 04dee9e85cf50a2f24738e456d66b88de109b806 Mon Sep 17 00:00:00 2001
From: Hugh Dickins
Date: Thu, 8 Jun 2023 18:29:22 -0700
Subject: mm/various: give up if pte_offset_map[_lock]() fails

Following the examples of nearby code, various functions can just give up
if pte_offset_map() or pte_offset_map_lock() fails.  And there's no need
for a preliminary pmd_trans_unstable() or other such check, since such
cases are now safely handled inside.

Link: https://lkml.kernel.org/r/7b9bd85d-1652-cbf2-159d-f503b45e5b@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zack Rusin <zackr@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/gup.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

(limited to 'mm/gup.c')

diff --git a/mm/gup.c b/mm/gup.c
index d448fd286b8c..598e8c98367b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -545,10 +545,10 @@ static struct page *follow_page_pte(struct vm_area_struct *vma,
 	if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
 			 (FOLL_PIN | FOLL_GET)))
 		return ERR_PTR(-EINVAL);
-	if (unlikely(pmd_bad(*pmd)))
-		return no_page_table(vma, flags);
 
 	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (!ptep)
+		return no_page_table(vma, flags);
 	pte = *ptep;
 	if (!pte_present(pte))
 		goto no_page;
@@ -852,8 +852,9 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
 	pmd = pmd_offset(pud, address);
 	if (!pmd_present(*pmd))
 		return -EFAULT;
-	VM_BUG_ON(pmd_trans_huge(*pmd));
 	pte = pte_offset_map(pmd, address);
+	if (!pte)
+		return -EFAULT;
 	if (pte_none(*pte))
 		goto unmap;
 	*vma = get_gate_vma(mm);
@@ -2468,6 +2469,8 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr,
 	pte_t *ptep, *ptem;
 
 	ptem = ptep = pte_offset_map(&pmd, addr);
+	if (!ptep)
+		return 0;
 	do {
 		pte_t pte = ptep_get_lockless(ptep);
 		struct page *page;
-- 
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