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| author | Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> | 2012-07-03 14:31:43 +0800 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-07-03 17:31:50 -0300 |
| commit | 85b7059169e128c57a3a8a3e588fb89cb2031da1 (patch) | |
| tree | 9934b741d6b66addd0b215e77ff60503e897cd02 | |
| parent | f411930442e01f9cf1bf4df41ff7e89476575c4d (diff) | |
| download | linux-85b7059169e128c57a3a8a3e588fb89cb2031da1.tar.bz2 | |
KVM: MMU: fix shrinking page from the empty mmu
Fix:
[ 3190.059226] BUG: unable to handle kernel NULL pointer dereference at (null)
[ 3190.062224] IP: [<ffffffffa02aac66>] mmu_page_zap_pte+0x10/0xa7 [kvm]
[ 3190.063760] PGD 104f50067 PUD 112bea067 PMD 0
[ 3190.065309] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
[ 3190.066860] CPU 1
[ ...... ]
[ 3190.109629] Call Trace:
[ 3190.111342] [<ffffffffa02aada6>] kvm_mmu_prepare_zap_page+0xa9/0x1fc [kvm]
[ 3190.113091] [<ffffffffa02ab2f5>] mmu_shrink+0x11f/0x1f3 [kvm]
[ 3190.114844] [<ffffffffa02ab25d>] ? mmu_shrink+0x87/0x1f3 [kvm]
[ 3190.116598] [<ffffffff81150c9d>] ? prune_super+0x142/0x154
[ 3190.118333] [<ffffffff8110a4f4>] ? shrink_slab+0x39/0x31e
[ 3190.120043] [<ffffffff8110a687>] shrink_slab+0x1cc/0x31e
[ 3190.121718] [<ffffffff8110ca1d>] do_try_to_free_pages
This is caused by shrinking page from the empty mmu, although we have
checked n_used_mmu_pages, it is useless since the check is out of mmu-lock
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index be3cea4407ff..57e168e27b5b 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -3934,6 +3934,9 @@ static void kvm_mmu_remove_some_alloc_mmu_pages(struct kvm *kvm, { struct kvm_mmu_page *page; + if (list_empty(&kvm->arch.active_mmu_pages)) + return; + page = container_of(kvm->arch.active_mmu_pages.prev, struct kvm_mmu_page, link); kvm_mmu_prepare_zap_page(kvm, page, invalid_list); |