Created attachment 1044685 [details] dmesg output Description of problem: Running a KVM guest fails with lots of errors like: [ 212.820766] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:616 [ 212.820933] in_atomic(): 1, irqs_disabled(): 0, pid: 2887, name: qemu-system-x86 [ 212.821119] INFO: lockdep is turned off. [ 212.821122] CPU: 4 PID: 2887 Comm: qemu-system-x86 Tainted: G W I 4.2.0-0.rc0.git2.1.fc23.x86_64 #1 [ 212.821124] Hardware name: Dell Inc. Precision WorkStation T5500 /0D883F, BIOS A12 12/29/2011 [ 212.821125] 0000000000000000 00000000172259b3 ffff880fa627fc58 ffffffff81856f03 [ 212.821129] 0000000000000000 ffff8800d30bddc0 ffff880fa627fc88 ffffffff810d9f91 [ 212.821132] 0000000000000001 ffffffff81c7cdbe 0000000000000268 0000000000000000 [ 212.821135] Call Trace: [ 212.821142] [<ffffffff81856f03>] dump_stack+0x4c/0x65 [ 212.821146] [<ffffffff810d9f91>] ___might_sleep+0x181/0x240 [ 212.821149] [<ffffffff810da09d>] __might_sleep+0x4d/0x90 [ 212.821152] [<ffffffff8185cade>] mutex_lock_nested+0x3e/0x3e0 [ 212.821156] [<ffffffff81104e6d>] ? trace_hardirqs_on+0xd/0x10 [ 212.821173] [<ffffffffa049af96>] ? vcpu_load+0x26/0x70 [kvm] [ 212.821183] [<ffffffffa049af96>] ? vcpu_load+0x26/0x70 [kvm] [ 212.821186] [<ffffffff811dcff4>] static_key_slow_inc+0x44/0xc0 [ 212.821188] [<ffffffff810d8ead>] preempt_notifier_register+0x1d/0x60 [ 212.821197] [<ffffffffa049afb5>] vcpu_load+0x45/0x70 [kvm] [ 212.821206] [<ffffffffa049b0a1>] kvm_vcpu_ioctl+0x81/0x820 [kvm] [ 212.821209] [<ffffffff810d4bed>] ? creds_are_invalid+0x1d/0x20 [ 212.821213] [<ffffffff8139ccaa>] ? inode_has_perm.isra.46+0x2a/0xa0 [ 212.821216] [<ffffffff8128316e>] do_vfs_ioctl+0x2ee/0x550 [ 212.821218] [<ffffffff8128f475>] ? __fget+0x5/0x1f0 [ 212.821221] [<ffffffff8139d37b>] ? selinux_file_ioctl+0x5b/0xf0 [ 212.821223] [<ffffffff81283449>] SyS_ioctl+0x79/0x90 [ 212.821226] [<ffffffff8186062e>] entry_SYSCALL_64_fastpath+0x12/0x76 [ 213.821575] BUG: sleeping function called from invalid context at kernel/cpu.c:94 [ 213.821736] in_atomic(): 1, irqs_disabled(): 0, pid: 2887, name: qemu-system-x86 [ 213.821963] INFO: lockdep is turned off. [ 213.821966] CPU: 4 PID: 2887 Comm: qemu-system-x86 Tainted: G W I 4.2.0-0.rc0.git2.1.fc23.x86_64 #1 [ 213.821968] Hardware name: Dell Inc. Precision WorkStation T5500 /0D883F, BIOS A12 12/29/2011 [ 213.821969] 0000000000000000 00000000172259b3 ffff880fa627fc18 ffffffff81856f03 [ 213.821972] 0000000000000000 ffff8800d30bddc0 ffff880fa627fc48 ffffffff810d9f91 [ 213.821975] ffff880fa627fc58 ffffffff81c7967e 000000000000005e 0000000000000000 [ 213.821978] Call Trace: [ 213.821982] [<ffffffff81856f03>] dump_stack+0x4c/0x65 [ 213.821984] [<ffffffff810d9f91>] ___might_sleep+0x181/0x240 [ 213.821986] [<ffffffff810da09d>] __might_sleep+0x4d/0x90 [ 213.821990] [<ffffffff810ab620>] get_online_cpus+0x20/0x80 [ 213.821993] [<ffffffff810ab6c7>] ? put_online_cpus+0x47/0x90 [ 213.821997] [<ffffffff810220fe>] arch_jump_label_transform+0x2e/0x120 [ 213.821999] [<ffffffff811dcd68>] __jump_label_update+0x58/0x70 [ 213.822002] [<ffffffff811dce1b>] jump_label_update+0x9b/0xb0 [ 213.822004] [<ffffffff811dd0c1>] __static_key_slow_dec+0x51/0xb0 [ 213.822006] [<ffffffff811dd146>] static_key_slow_dec+0x26/0x50 [ 213.822008] [<ffffffff810d8ca3>] preempt_notifier_unregister+0x43/0x50 [ 213.822019] [<ffffffffa049b006>] vcpu_put+0x26/0x40 [kvm] [ 213.822028] [<ffffffffa049b14d>] kvm_vcpu_ioctl+0x12d/0x820 [kvm] [ 213.822031] [<ffffffff810d4bed>] ? creds_are_invalid+0x1d/0x20 [ 213.822034] [<ffffffff8139ccaa>] ? inode_has_perm.isra.46+0x2a/0xa0 [ 213.822036] [<ffffffff8128316e>] do_vfs_ioctl+0x2ee/0x550 [ 213.822039] [<ffffffff8128f475>] ? __fget+0x5/0x1f0 [ 213.822041] [<ffffffff8139d37b>] ? selinux_file_ioctl+0x5b/0xf0 [ 213.822043] [<ffffffff81283449>] SyS_ioctl+0x79/0x90 [ 213.822046] [<ffffffff8186062e>] entry_SYSCALL_64_fastpath+0x12/0x76 Version-Release number of selected component (if applicable): kernel 4.2.0-0.rc0.git2.1.fc23.x86_64 How reproducible: 100% Steps to Reproduce: 1. Run a KVM guest, or libguestfs-test-tool. Actual results: See attached dmesg.
http://article.gmane.org/gmane.linux.kernel/1983762 is the fix I think.
(The lockdep splats from the fib code have a fix elsewhere too I believe).
(In reply to Josh Boyer from comment #1) > http://article.gmane.org/gmane.linux.kernel/1983762 is the fix I think. I added this patch to the git3 build I just started. Please test when it is available.
Josh, please revert the original patch instead.
(In reply to Paolo Bonzini from comment #4) > Josh, please revert the original patch instead. Upstream seems to have fixed this with: commit 2ecd9d29abb171d6e97a4f3eb29d7456a11401b7 Author: Peter Zijlstra <peterz> Date: Fri Jul 3 18:53:58 2015 +0200 sched, preempt_notifier: separate notifier registration from static_key inc/ dec That's in 4.2-rc1. So if something needs to be reverted, it needs to be done upstream at this point.