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authorLiu Shixin <liushixin2@huawei.com>2022-11-17 10:56:01 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2022-11-18 22:31:54 +0300
commit5b47348fc0b18a78c96f8474cc90b7525ad1bbfe (patch)
tree7c64e9f33941427be614ad8d04864560ac79716c /README
parent2598ac6ec493566105f8a1029aa9de36ba6946ca (diff)
downloadlinux-5b47348fc0b18a78c96f8474cc90b7525ad1bbfe.tar.xz
arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud
The page table check trigger BUG_ON() unexpectedly when collapse hugepage: ------------[ cut here ]------------ kernel BUG at mm/page_table_check.c:82! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750 Hardware name: linux,dummy-virt (DT) pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : page_table_check_clear.isra.0+0x258/0x3f0 lr : page_table_check_clear.isra.0+0x240/0x3f0 [...] Call trace: page_table_check_clear.isra.0+0x258/0x3f0 __page_table_check_pmd_clear+0xbc/0x108 pmdp_collapse_flush+0xb0/0x160 collapse_huge_page+0xa08/0x1080 hpage_collapse_scan_pmd+0xf30/0x1590 khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8 khugepaged+0x338/0x518 kthread+0x278/0x2f8 ret_from_fork+0x10/0x20 [...] Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it decrease file_map_count for a non-leaf pmd comes from collapse_huge_page(). and so trigger BUG_ON() unexpectedly. Fix this problem by using pmd_leaf() insteal of pmd_present() in pmd_user_accessible_page(). Moreover, use pud_leaf() for pud_user_accessible_page() too. Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK") Reported-by: Denys Vlasenko <dvlasenk@redhat.com> Signed-off-by: Liu Shixin <liushixin2@huawei.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20221117075602.2904324-2-liushixin2@huawei.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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