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authorMark Salter <msalter@redhat.com>2014-05-15 15:19:22 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2014-05-16 17:34:40 +0100
commit4797ec2dc83a43be35bad56037d1b53db9e2b5d5 (patch)
tree1a28099cfb66a21de7a56c77de66acb908d1bc71
parent601c942176d8ad8334118bddb747e3720bed24f8 (diff)
downloadlinux-4797ec2dc83a43be35bad56037d1b53db9e2b5d5.tar.gz
arm64: fix pud_huge() for 2-level pagetables
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+
-rw-r--r--arch/arm64/mm/hugetlbpage.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 5e9aec358306..31eb959e9aa8 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -51,7 +51,11 @@ int pmd_huge(pmd_t pmd)
int pud_huge(pud_t pud)
{
+#ifndef __PAGETABLE_PMD_FOLDED
return !(pud_val(pud) & PUD_TABLE_BIT);
+#else
+ return 0;
+#endif
}
int pmd_huge_support(void)