The patch titled Subject: arch/x86/mm/hugetlbpage.c: pud_huge() returns 0 when using 2-level paging has been added to the -mm mm-hotfixes-unstable branch. Its filename is arch-x86-mm-hugetlbpagec-pud_huge-returns-0-when-using-2-level-paging.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-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: Naoya Horiguchi naoya.horiguchi@nec.com Subject: arch/x86/mm/hugetlbpage.c: pud_huge() returns 0 when using 2-level paging Date: Mon, 7 Nov 2022 11:10:10 +0900

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 pmd_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 naoya.horiguchi@nec.com Reported-by: Ville Syrj��l�� ville.syrjala@linux.intel.com Tested-by: Ville Syrj��l�� ville.syrjala@linux.intel.com Cc: David Hildenbrand david@redhat.com Cc: Liu Shixin liushixin2@huawei.com Cc: Miaohe Lin linmiaohe@huawei.com Cc: Mike Kravetz mike.kravetz@oracle.com Cc: Muchun Song songmuchun@bytedance.com Cc: Oscar Salvador osalvador@suse.de Cc: Yang Shi shy828301@gmail.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Dave Hansen dave.hansen@linux.intel.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

arch/x86/mm/hugetlbpage.c | 4 ++++ 1 file changed, 4 insertions(+)

--- a/arch/x86/mm/hugetlbpage.c~arch-x86-mm-hugetlbpagec-pud_huge-returns-0-when-using-2-level-paging +++ a/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 _

Patches currently in -mm which might be from naoya.horiguchi@nec.com are

arch-x86-mm-hugetlbpagec-pud_huge-returns-0-when-using-2-level-paging.patch mmhwpoisonhugetlbmemory_hotplug-hotremove-memory-section-with-hwpoisoned-hugepage.patch mm-hwpoison-move-definitions-of-num_poisoned_pages_-to-memory-failurec.patch mm-hwpoison-pass-pfn-to-num_poisoned_pages_.patch mm-hwpoison-introduce-per-memory_block-hwpoison-counter.patch