This is a note to let you know that I've just added the patch titled
arm64: fix pud_huge() for 2-level pagetables
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-fix-pud_huge-for-2-level-pagetables.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4797ec2dc83a43be35bad56037d1b53db9e2b5d5 Mon Sep 17 00:00:00 2001
From: Mark Salter <msalter@xxxxxxxxxx>
Date: Thu, 15 May 2014 15:19:22 +0100
Subject: arm64: fix pud_huge() for 2-level pagetables
From: Mark Salter <msalter@xxxxxxxxxx>
commit 4797ec2dc83a43be35bad56037d1b53db9e2b5d5 upstream.
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@xxxxxxxxxx>
[catalin.marinas@xxxxxxx: removed #ifndef around PUD_SIZE check]
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/hugetlbpage.c | 4 ++++
1 file changed, 4 insertions(+)
--- 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)
Patches currently in stable-queue which might be from msalter@xxxxxxxxxx are
queue-3.14/arm64-fix-pud_huge-for-2-level-pagetables.patch
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