A recently introduced helper for handling zap vs. remote flush
incorrectly bails early, effectively leaking defunct shadow pages.
Manifests as a slab BUG when exiting KVM due to the shadow pages
being alive when their associated cache is destroyed.
==========================================================================
BUG kvm_mmu_page_header: Objects remaining in kvm_mmu_page_header on ...
--------------------------------------------------------------------------
Disabling lock debugging due to kernel taint
INFO: Slab 0x00000000fc436387 objects=26 used=23 fp=0x00000000d023caee ...
CPU: 6 PID: 4315 Comm: rmmod Tainted: G B 5.1.0-rc2+ #19
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
dump_stack+0x46/0x5b
slab_err+0xad/0xd0
? on_each_cpu_mask+0x3c/0x50
? ksm_migrate_page+0x60/0x60
? on_each_cpu_cond_mask+0x7c/0xa0
? __kmalloc+0x1ca/0x1e0
__kmem_cache_shutdown+0x13a/0x310
shutdown_cache+0xf/0x130
kmem_cache_destroy+0x1d5/0x200
kvm_mmu_module_exit+0xa/0x30 [kvm]
kvm_arch_exit+0x45/0x60 [kvm]
kvm_exit+0x6f/0x80 [kvm]
vmx_exit+0x1a/0x50 [kvm_intel]
__x64_sys_delete_module+0x153/0x1f0
? exit_to_usermode_loop+0x88/0xc0
do_syscall_64+0x4f/0x100
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: a21136345cb6f ("KVM: x86/mmu: Split remote_flush+zap case out of kvm_mmu_flush_or_zap()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/mmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bd0727019674..e10962dfc203 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2238,7 +2238,7 @@ static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm,
struct list_head *invalid_list,
bool remote_flush)
{
- if (!remote_flush && !list_empty(invalid_list))
+ if (!remote_flush && list_empty(invalid_list))
return false;
if (!list_empty(invalid_list))
--
2.21.0
