+ mm-various-give-up-if-pte_offset_map-fails.patch added to mm-unstable branch

+ mm-various-give-up-if-pte_offset_map-fails.patch added to mm-unstable branch

[Andrew Morton]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 9694 bytes --]


The patch titled
     Subject: mm/various: give up if pte_offset_map[_lock]() fails
has been added to the -mm mm-unstable branch.  Its filename is
     mm-various-give-up-if-pte_offset_map-fails.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-various-give-up-if-pte_offset_map-fails.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Hugh Dickins <hughd@google.com>
Subject: mm/various: give up if pte_offset_map[_lock]() fails
Date: Thu, 8 Jun 2023 18:29:22 -0700 (PDT)

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 ++++++---
 mm/ksm.c            |    7 ++++---
 mm/memcontrol.c     |    8 ++++----
 mm/memory-failure.c |    8 +++++---
 mm/migrate.c        |    3 +++
 5 files changed, 22 insertions(+), 13 deletions(-)

--- a/mm/gup.c~mm-various-give-up-if-pte_offset_map-fails
+++ a/mm/gup.c
@@ -545,10 +545,10 @@ static struct page *follow_page_pte(stru
 	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_struc
 	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_
 	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;
--- a/mm/ksm.c~mm-various-give-up-if-pte_offset_map-fails
+++ a/mm/ksm.c
@@ -431,10 +431,9 @@ static int break_ksm_pmd_entry(pmd_t *pm
 	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_s
 	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;
--- a/mm/memcontrol.c~mm-various-give-up-if-pte_offset_map-fails
+++ a/mm/memcontrol.c
@@ -6021,9 +6021,9 @@ static int mem_cgroup_count_precharge_pt
 		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_ra
 		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;
--- a/mm/memory-failure.c~mm-various-give-up-if-pte_offset_map-fails
+++ a/mm/memory-failure.c
@@ -405,6 +405,8 @@ static unsigned long dev_pagemap_mapping
 	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 *pmd
 		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);
--- a/mm/migrate.c~mm-various-give-up-if-pte_offset_map-fails
+++ a/mm/migrate.c
@@ -305,6 +305,9 @@ void migration_entry_wait(struct mm_stru
 	swp_entry_t entry;
 
 	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
+	if (!ptep)
+		return;
+
 	pte = *ptep;
 	pte_unmap(ptep);
 
_

Patches currently in -mm which might be from hughd@google.com are

arm-allow-pte_offset_map-to-fail.patch
arm64-allow-pte_offset_map-to-fail.patch
arm64-hugetlb-pte_alloc_huge-pte_offset_huge.patch
ia64-hugetlb-pte_alloc_huge-pte_offset_huge.patch
m68k-allow-pte_offset_map-to-fail.patch
microblaze-allow-pte_offset_map-to-fail.patch
mips-update_mmu_cache-can-replace-__update_tlb.patch
mips-update_mmu_cache-can-replace-__update_tlb-fix.patch
parisc-add-pte_unmap-to-balance-get_ptep.patch
parisc-unmap_uncached_pte-use-pte_offset_kernel.patch
parisc-hugetlb-pte_alloc_huge-pte_offset_huge.patch
powerpc-kvmppc_unmap_free_pmd-pte_offset_kernel.patch
powerpc-allow-pte_offset_map-to-fail.patch
powerpc-hugetlb-pte_alloc_huge.patch
riscv-hugetlb-pte_alloc_huge-pte_offset_huge.patch
s390-allow-pte_offset_map_lock-to-fail.patch
s390-gmap-use-pte_unmap_unlock-not-spin_unlock.patch
sh-hugetlb-pte_alloc_huge-pte_offset_huge.patch
sparc-hugetlb-pte_alloc_huge-pte_offset_huge.patch
sparc-allow-pte_offset_map-to-fail.patch
sparc-iounit-and-iommu-use-pte_offset_kernel.patch
x86-allow-get_locked_pte-to-fail.patch
x86-sme_populate_pgd-use-pte_offset_kernel.patch
xtensa-add-pte_unmap-to-balance-pte_offset_map.patch
mm-use-pmdp_get_lockless-without-surplus-barrier.patch
mm-migrate-remove-cruft-from-migration_entry_waits.patch
mm-pgtable-kmap_local_page-instead-of-kmap_atomic.patch
mm-pgtable-allow-pte_offset_map-to-fail.patch
mm-filemap-allow-pte_offset_map_lock-to-fail.patch
mm-page_vma_mapped-delete-bogosity-in-page_vma_mapped_walk.patch
mm-page_vma_mapped-reformat-map_pte-with-less-indentation.patch
mm-page_vma_mapped-pte_offset_map_nolock-not-pte_lockptr.patch
mm-pagewalkers-action_again-if-pte_offset_map_lock-fails.patch
mm-pagewalk-walk_pte_range-allow-for-pte_offset_map.patch
mm-vmwgfx-simplify-pmd-pud-mapping-dirty-helpers.patch
mm-vmalloc-vmalloc_to_page-use-pte_offset_kernel.patch
mm-hmm-retry-if-pte_offset_map-fails.patch
mm-userfaultfd-retry-if-pte_offset_map-fails.patch
mm-userfaultfd-allow-pte_offset_map_lock-to-fail.patch
mm-debug_vm_pgtablepage_table_check-warn-pte-map-fails.patch
mm-various-give-up-if-pte_offset_map-fails.patch
mm-mprotect-delete-pmd_none_or_clear_bad_unless_trans_huge.patch
mm-mremap-retry-if-either-pte_offset_map_lock-fails.patch
mm-madvise-clean-up-pte_offset_map_lock-scans.patch
mm-madvise-clean-up-force_shm_swapin_readahead.patch
mm-swapoff-allow-pte_offset_map-to-fail.patch
mm-mglru-allow-pte_offset_map_nolock-to-fail.patch
mm-migrate_device-allow-pte_offset_map_lock-to-fail.patch
mm-gup-remove-foll_split_pmd-use-of-pmd_trans_unstable.patch
mm-huge_memory-split-huge-pmd-under-one-pte_offset_map.patch
mm-khugepaged-allow-pte_offset_map-to-fail.patch
mm-memory-allow-pte_offset_map-to-fail.patch
mm-memory-handle_pte_fault-use-pte_offset_map_nolock.patch
mm-pgtable-delete-pmd_trans_unstable-and-friends.patch
mm-swap-swap_vma_readahead-do-the-pte_offset_map.patch
perf-core-allow-pte_offset_map-to-fail.patch