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>

diff --git a/mm/gup.c b/mm/gup.c
index d448fd2..598e8c9 100644 (file)
--- 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;

diff --git a/mm/ksm.c b/mm/ksm.c
index df2aa28..3dc1545 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -431,10 +431,9 @@ static int break_ksm_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long nex
        pte_t *pte;
        int ret;
 
-       if (pmd_leaf(*pmd) || !pmd_present(*pmd))
-               return 0;
-
        pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+       if (!pte)
+               return 0;
        if (pte_present(*pte)) {
                page = vm_normal_page(walk->vma, addr, *pte);
        } else if (!pte_none(*pte)) {
@@ -1203,6 +1202,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
        mmu_notifier_invalidate_range_start(&range);
 
        ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+       if (!ptep)
+               goto out_mn;
        if (!pte_same(*ptep, orig_pte)) {
                pte_unmap_unlock(ptep, ptl);
                goto out_mn;

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index caf6ab5..77d8d2d 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6021,9 +6021,9 @@ static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
                return 0;
        }
 
-       if (pmd_trans_unstable(pmd))
-               return 0;
        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+       if (!pte)
+               return 0;
        for (; addr != end; pte++, addr += PAGE_SIZE)
                if (get_mctgt_type(vma, addr, *pte, NULL))
                        mc.precharge++; /* increment precharge temporarily */
@@ -6241,10 +6241,10 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
                return 0;
        }
 
-       if (pmd_trans_unstable(pmd))
-               return 0;
 retry:
        pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+       if (!pte)
+               return 0;
        for (; addr != end; addr += PAGE_SIZE) {
                pte_t ptent = *(pte++);
                bool device = false;

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 004a02f..d5116f0 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -405,6 +405,8 @@ static unsigned long dev_pagemap_mapping_shift(struct vm_area_struct *vma,
        if (pmd_devmap(*pmd))
                return PMD_SHIFT;
        pte = pte_offset_map(pmd, address);
+       if (!pte)
+               return 0;
        if (pte_present(*pte) && pte_devmap(*pte))
                ret = PAGE_SHIFT;
        pte_unmap(pte);
@@ -791,11 +793,11 @@ static int hwpoison_pte_range(pmd_t *pmdp, unsigned long addr,
                goto out;
        }
 
-       if (pmd_trans_unstable(pmdp))
-               goto out;
-
        mapped_pte = ptep = pte_offset_map_lock(walk->vma->vm_mm, pmdp,
                                                addr, &ptl);
+       if (!ptep)
+               goto out;
+
        for (; addr != end; ptep++, addr += PAGE_SIZE) {
                ret = check_hwpoisoned_entry(*ptep, addr, PAGE_SHIFT,
                                             hwp->pfn, &hwp->tk);

diff --git a/mm/migrate.c b/mm/migrate.c
index c1f2c40..3635629 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -305,6 +305,9 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
        swp_entry_t entry;
 
        ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+       if (!ptep)
+               return;
+
        pte = *ptep;
        pte_unmap(ptep);