The patch titled
Subject: powerpc: allow pte_offset_map[_lock]() to fail
has been added to the -mm mm-unstable branch. Its filename is
powerpc-allow-pte_offset_map-to-fail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerpc-allow-pte_offset_map-to-fail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Hugh Dickins <hughd@xxxxxxxxxx>
Subject: powerpc: allow pte_offset_map[_lock]() to fail
Date: Thu, 8 Jun 2023 12:23:35 -0700 (PDT)
In rare transient cases, not yet made possible, pte_offset_map() and
pte_offset_map_lock() may not find a page table: handle appropriately.
Balance successful pte_offset_map() with pte_unmap() where omitted.
Link: https://lkml.kernel.org/r/54c8b578-ca9-a0f-bfd2-d72976f8d73a@xxxxxxxxxx
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Chris Zankel <chris@xxxxxxxxxx>
Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Helge Deller <deller@xxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: John David Anglin <dave.anglin@xxxxxxxx>
Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Max Filippov <jcmvbkbc@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Michal Simek <monstr@xxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/book3s64/hash_tlb.c | 4 ++++
arch/powerpc/mm/book3s64/subpage_prot.c | 2 ++
arch/powerpc/xmon/xmon.c | 5 ++++-
3 files changed, 10 insertions(+), 1 deletion(-)
--- a/arch/powerpc/mm/book3s64/hash_tlb.c~powerpc-allow-pte_offset_map-to-fail
+++ a/arch/powerpc/mm/book3s64/hash_tlb.c
@@ -239,12 +239,16 @@ void flush_hash_table_pmd_range(struct m
local_irq_save(flags);
arch_enter_lazy_mmu_mode();
start_pte = pte_offset_map(pmd, addr);
+ if (!start_pte)
+ goto out;
for (pte = start_pte; pte < start_pte + PTRS_PER_PTE; pte++) {
unsigned long pteval = pte_val(*pte);
if (pteval & H_PAGE_HASHPTE)
hpte_need_flush(mm, addr, pte, pteval, 0);
addr += PAGE_SIZE;
}
+ pte_unmap(start_pte);
+out:
arch_leave_lazy_mmu_mode();
local_irq_restore(flags);
}
--- a/arch/powerpc/mm/book3s64/subpage_prot.c~powerpc-allow-pte_offset_map-to-fail
+++ a/arch/powerpc/mm/book3s64/subpage_prot.c
@@ -71,6 +71,8 @@ static void hpte_flush_range(struct mm_s
if (pmd_none(*pmd))
return;
pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ if (!pte)
+ return;
arch_enter_lazy_mmu_mode();
for (; npages > 0; --npages) {
pte_update(mm, addr, pte, 0, 0, 0);
--- a/arch/powerpc/xmon/xmon.c~powerpc-allow-pte_offset_map-to-fail
+++ a/arch/powerpc/xmon/xmon.c
@@ -3376,12 +3376,15 @@ static void show_pte(unsigned long addr)
printf("pmdp @ 0x%px = 0x%016lx\n", pmdp, pmd_val(*pmdp));
ptep = pte_offset_map(pmdp, addr);
- if (pte_none(*ptep)) {
+ if (!ptep || pte_none(*ptep)) {
+ if (ptep)
+ pte_unmap(ptep);
printf("no valid PTE\n");
return;
}
format_pte(ptep, pte_val(*ptep));
+ pte_unmap(ptep);
sync();
__delay(200);
_
Patches currently in -mm which might be from hughd@xxxxxxxxxx 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
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
