From 1fdbed657a4726639c4f17841fd2a0fb646c746e Mon Sep 17 00:00:00 2001 From: Naoya Horiguchi Date: Mon, 7 Nov 2022 11:10:10 +0900 Subject: [PATCH] arch/x86/mm/hugetlbpage.c: pud_huge() returns 0 when using 2-level paging MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The following bug is reported to be triggered when starting X on x86-32 system with i915: [ 225.777375] kernel BUG at mm/memory.c:2664! [ 225.777391] invalid opcode: 0000 [#1] PREEMPT SMP [ 225.777405] CPU: 0 PID: 2402 Comm: Xorg Not tainted 6.1.0-rc3-bdg+ #86 [ 225.777415] Hardware name: /8I865G775-G, BIOS F1 08/29/2006 [ 225.777421] EIP: __apply_to_page_range+0x24d/0x31c [ 225.777437] Code: ff ff 8b 55 e8 8b 45 cc e8 0a 11 ec ff 89 d8 83 c4 28 5b 5e 5f 5d c3 81 7d e0 a0 ef 96 c1 74 ad 8b 45 d0 e8 2d 83 49 00 eb a3 <0f> 0b 25 00 f0 ff ff 81 eb 00 00 00 40 01 c3 8b 45 ec 8b 00 e8 76 [ 225.777446] EAX: 00000001 EBX: c53a3b58 ECX: b5c00000 EDX: c258aa00 [ 225.777454] ESI: b5c00000 EDI: b5900000 EBP: c4b0fdb4 ESP: c4b0fd80 [ 225.777462] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010202 [ 225.777470] CR0: 80050033 CR2: b5900000 CR3: 053a3000 CR4: 000006d0 [ 225.777479] Call Trace: [ 225.777486] ? i915_memcpy_init_early+0x63/0x63 [i915] [ 225.777684] apply_to_page_range+0x21/0x27 [ 225.777694] ? i915_memcpy_init_early+0x63/0x63 [i915] [ 225.777870] remap_io_mapping+0x49/0x75 [i915] [ 225.778046] ? i915_memcpy_init_early+0x63/0x63 [i915] [ 225.778220] ? mutex_unlock+0xb/0xd [ 225.778231] ? i915_vma_pin_fence+0x6d/0xf7 [i915] [ 225.778420] vm_fault_gtt+0x2a9/0x8f1 [i915] [ 225.778644] ? lock_is_held_type+0x56/0xe7 [ 225.778655] ? lock_is_held_type+0x7a/0xe7 [ 225.778663] ? 0xc1000000 [ 225.778670] __do_fault+0x21/0x6a [ 225.778679] handle_mm_fault+0x708/0xb21 [ 225.778686] ? mt_find+0x21e/0x5ae [ 225.778696] exc_page_fault+0x185/0x705 [ 225.778704] ? doublefault_shim+0x127/0x127 [ 225.778715] handle_exception+0x130/0x130 [ 225.778723] EIP: 0xb700468a Recently pud_huge() got aware of non-present entry by commit 3a194f3f8ad0 ("mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry") to handle some special states of gigantic page. However, it's overlooked that pud_none() always returns false when running with 2-level paging, and as a result pud_huge() can return true pointlessly. Introduce "#if CONFIG_PGTABLE_LEVELS > 2" to pud_huge() to deal with this. Link: https://lkml.kernel.org/r/20221107021010.2449306-1-naoya.horiguchi@linux.dev Fixes: 3a194f3f8ad0 ("mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry") Signed-off-by: Naoya Horiguchi Reported-by: Ville Syrjälä Tested-by: Ville Syrjälä Reviewed-by: Miaohe Lin Cc: David Hildenbrand Cc: Liu Shixin Cc: Mike Kravetz Cc: Muchun Song Cc: Oscar Salvador Cc: Yang Shi Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Signed-off-by: Andrew Morton --- arch/x86/mm/hugetlbpage.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c index 6b30338..5804bba 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -37,8 +37,12 @@ int pmd_huge(pmd_t pmd) */ int pud_huge(pud_t pud) { +#if CONFIG_PGTABLE_LEVELS > 2 return !pud_none(pud) && (pud_val(pud) & (_PAGE_PRESENT|_PAGE_PSE)) != _PAGE_PRESENT; +#else + return 0; +#endif } #ifdef CONFIG_HUGETLB_PAGE -- 2.7.4