KVM guests with CONFIG_LOCKDEP=y trigger the following warning: BUG: MAX_LOCK_DEPTH too low! turning off the locking correctness validator. Pid: 4624, comm: qemu-system-x86 Not tainted 2.6.31-rc2-03981-g3abaf21 #32 Call Trace: [<ffffffff81068bab>] __lock_acquire+0x1559/0x15fc [<ffffffff810be4d9>] ? mm_take_all_locks+0x99/0x109 [<ffffffff810be4d9>] ? mm_take_all_locks+0x99/0x109 [<ffffffff81068d3c>] lock_acquire+0xee/0x112 [<ffffffff810be516>] ? mm_take_all_locks+0xd6/0x109 [<ffffffff81402596>] ? _spin_lock_nest_lock+0x20/0x50 [<ffffffff814025b7>] _spin_lock_nest_lock+0x41/0x50 [<ffffffff810be516>] ? mm_take_all_locks+0xd6/0x109 [<ffffffff810be516>] mm_take_all_locks+0xd6/0x109 [<ffffffff810d0f76>] do_mmu_notifier_register+0xd4/0x199 [<ffffffff810d1060>] mmu_notifier_register+0x13/0x15 [<ffffffffa0107f16>] kvm_dev_ioctl+0x13f/0x30e [kvm] [<ffffffff810e6a3a>] vfs_ioctl+0x2f/0x7d [<ffffffff810e6fb7>] do_vfs_ioctl+0x4af/0x4ec [<ffffffff814030b4>] ? error_exit+0x94/0xb0 [<ffffffff81401f92>] ? trace_hardirqs_off_thunk+0x3a/0x3c [<ffffffff8100bc2d>] ? retint_swapgs+0xe/0x13 [<ffffffff810e703b>] sys_ioctl+0x47/0x6a [<ffffffff811d849c>] ? __up_read+0x1a/0x85 [<ffffffff8100b1db>] system_call_fastpath+0x16/0x1b Since mm_take_all_locks takes a gazillion locks. Is there any way around this other than completly shutting down lockdep? diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index 5f4ef02..0c43cae 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -148,6 +148,8 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn, struct mmu_notifier_mm *mmu_notifier_mm; int ret; + lockdep_off(); + BUG_ON(atomic_read(&mm->mm_users) <= 0); ret = -ENOMEM; @@ -189,6 +191,7 @@ out_cleanup: kfree(mmu_notifier_mm); out: BUG_ON(atomic_read(&mm->mm_users) <= 0); + lockdep_on(); return ret; } -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
