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Anshuman Khandual ff40839e01 mm/ptdump: take the memory hotplug lock inside ptdump_walk_pgd() ... commit 59305202c6 upstream. Memory hot remove unmaps and tears down various kernel page table regions as required. The ptdump code can race with concurrent modifications of the kernel page tables. When leaf entries are modified concurrently, the dump code may log stale or inconsistent information for a VA range, but this is otherwise not harmful. But when intermediate levels of kernel page table are freed, the dump code will continue to use memory that has been freed and potentially reallocated for another purpose. In such cases, the ptdump code may dereference bogus addresses, leading to a number of potential problems. To avoid the above mentioned race condition, platforms such as arm64, riscv and s390 take memory hotplug lock, while dumping kernel page table via the sysfs interface /sys/kernel/debug/kernel_page_tables. Similar race condition exists while checking for pages that might have been marked W+X via /sys/kernel/debug/kernel_page_tables/check_wx_pages which in turn calls ptdump_check_wx(). Instead of solving this race condition again, let's just move the memory hotplug lock inside generic ptdump_check_wx() which will benefit both the scenarios. Drop get_online_mems() and put_online_mems() combination from all existing platform ptdump code paths. Link: https://lkml.kernel.org/r/20250620052427.2092093-1-anshuman.khandual@arm.com Fixes: bbd6ec605c ("arm64/mm: Enable memory hot remove") Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dev Jain <dev.jain@arm.com> Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> [s390] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		History 2025-08-20 18:30:55 +02:00
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cache-ops.c	riscv: split cache ops out of dma-noncoherent.c	2023-11-07 09:37:42 -08:00
cacheflush.c	riscv: add a data fence for CMODX in the kernel mode	2025-07-06 11:01:35 +02:00
context.c	Merge patch series "riscv: ASID-related and UP-related TLB flush enhancements"	2024-04-30 10:35:48 -07:00
dma-noncoherent.c	dma-mapping: Simplify arch_setup_dma_ops()	2024-04-26 12:07:28 +02:00
extable.c	riscv: select DCACHE_WORD_ACCESS for efficient unaligned access HW	2024-01-09 20:18:20 -08:00
fault.c	riscv/mm: Add handling for VM_FAULT_SIGSEGV in mm_fault_error()	2024-08-01 07:15:27 -07:00
hugetlbpage.c	riscv: Fix hugetlb retrieval of number of ptes in case of !present pte	2025-04-10 14:39:32 +02:00
init.c	riscv: mm: Fix the out of bound issue of vmemmap address	2025-01-17 13:40:44 +01:00
kasan_init.c	percpu:	2024-01-18 15:01:28 -08:00
Makefile	riscv: mm: Combine the SMP and UP TLB flush code	2024-04-29 10:49:29 -07:00
pageattr.c	riscv: rewrite __kernel_map_pages() to fix sleeping in invalid context	2024-05-22 09:15:09 -07:00
pgtable.c	riscv: Stop emitting preventive sfence.vma for new userspace mappings with Svvptc	2024-09-15 00:11:05 -07:00
physaddr.c	riscv: Use PUD/P4D/PGD pages for the linear mapping	2023-04-18 20:43:04 -07:00
pmem.c	RISC-V: capitalise CMO op macros	2023-11-05 09:11:23 -08:00
ptdump.c	mm/ptdump: take the memory hotplug lock inside ptdump_walk_pgd()	2025-08-20 18:30:55 +02:00
tlbflush.c	riscv: Call secondary mmu notifier when flushing the tlb	2025-05-29 11:02:14 +02:00