4797ec2dc8
The following happens when trying to run a kvm guest on a kernel configured for 64k pages. This doesn't happen with 4k pages: BUG: failure at include/linux/mm.h:297/put_page_testzero()! Kernel panic - not syncing: BUG! CPU: 2 PID: 4228 Comm: qemu-system-aar Tainted: GF 3.13.0-0.rc7.31.sa2.k32v1.aarch64.debug #1 Call trace: [<fffffe0000096034>] dump_backtrace+0x0/0x16c [<fffffe00000961b4>] show_stack+0x14/0x1c [<fffffe000066e648>] dump_stack+0x84/0xb0 [<fffffe0000668678>] panic+0xf4/0x220 [<fffffe000018ec78>] free_reserved_area+0x0/0x110 [<fffffe000018edd8>] free_pages+0x50/0x88 [<fffffe00000a759c>] kvm_free_stage2_pgd+0x30/0x40 [<fffffe00000a5354>] kvm_arch_destroy_vm+0x18/0x44 [<fffffe00000a1854>] kvm_put_kvm+0xf0/0x184 [<fffffe00000a1938>] kvm_vm_release+0x10/0x1c [<fffffe00001edc1c>] __fput+0xb0/0x288 [<fffffe00001ede4c>] ____fput+0xc/0x14 [<fffffe00000d5a2c>] task_work_run+0xa8/0x11c [<fffffe0000095c14>] do_notify_resume+0x54/0x58 In arch/arm/kvm/mmu.c:unmap_range(), we end up doing an extra put_page() on the stage2 pgd which leads to the BUG in put_page_testzero(). This happens because a pud_huge() test in unmap_range() returns true when it should always be false with 2-level pages tables used by 64k pages. This patch removes support for huge puds if 2-level pagetables are being used. Signed-off-by: Mark Salter <msalter@redhat.com> [catalin.marinas@arm.com: removed #ifndef around PUD_SIZE check] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: <stable@vger.kernel.org> # v3.11+
79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/*
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* arch/arm64/mm/hugetlbpage.c
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*
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* Copyright (C) 2013 Linaro Ltd.
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*
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* Based on arch/x86/mm/hugetlbpage.c.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/pagemap.h>
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#include <linux/err.h>
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#include <linux/sysctl.h>
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#include <asm/mman.h>
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#include <asm/tlb.h>
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#include <asm/tlbflush.h>
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#include <asm/pgalloc.h>
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#ifndef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
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int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
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{
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return 0;
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}
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#endif
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struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
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int write)
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{
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return ERR_PTR(-EINVAL);
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}
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int pmd_huge(pmd_t pmd)
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{
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return !(pmd_val(pmd) & PMD_TABLE_BIT);
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}
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int pud_huge(pud_t pud)
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{
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#ifndef __PAGETABLE_PMD_FOLDED
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return !(pud_val(pud) & PUD_TABLE_BIT);
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#else
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return 0;
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#endif
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}
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int pmd_huge_support(void)
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{
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return 1;
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}
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static __init int setup_hugepagesz(char *opt)
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{
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unsigned long ps = memparse(opt, &opt);
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if (ps == PMD_SIZE) {
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hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
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} else if (ps == PUD_SIZE) {
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hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
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} else {
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pr_err("hugepagesz: Unsupported page size %lu M\n", ps >> 20);
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return 0;
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}
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return 1;
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}
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__setup("hugepagesz=", setup_hugepagesz);
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