Hand too fast on the trigger... sorry. It happened while fuzzing inside a KVM tools guest on the latest -next kernel. Seems to be pretty difficult to reproduce. Thanks, Sasha On 06/13/2014 08:53 AM, Sasha Levin wrote: > [ 7193.961785] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > [ 7193.961785] Dumping ftrace buffer: > [ 7193.961785] (ftrace buffer empty) > [ 7193.961785] Modules linked in: > [ 7193.961785] CPU: 2 PID: 4011 Comm: kswapd2 Not tainted 3.15.0-next-20140612-sasha-00022-g5e4db85-dirty #645 > [ 7193.961785] task: ffff880035563000 ti: ffff88003557c000 task.ti: ffff88003557c000 > [ 7193.961785] RIP: __lock_acquire (./arch/x86/include/asm/atomic.h:92 kernel/locking/lockdep.c:3082) > [ 7193.961785] RSP: 0000:ffff88003557f848 EFLAGS: 00010002 > [ 7193.961785] RAX: 0000000000000000 RBX: 6b6b6b6b6b6b6b6b RCX: 0000000000000000 > [ 7193.961785] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8800761fbae0 > [ 7193.961785] RBP: ffff88003557f938 R08: 0000000000000001 R09: 0000000000000000 > [ 7193.961785] R10: ffff8800761fbae0 R11: 0000000000000000 R12: ffff880035563000 > [ 7193.961785] R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000 > [ 7193.961785] FS: 0000000000000000(0000) GS:ffff8800a6e00000(0000) knlGS:0000000000000000 > [ 7193.961785] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 7193.961785] CR2: 0000000005aabfc8 CR3: 00000006d5276000 CR4: 00000000000006a0 > [ 7193.961785] DR0: 00000000006df000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 7193.961785] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 > [ 7193.961785] Stack: > [ 7193.961785] ffff88003557f948 ffffffff891cbe79 ffffffff908c1c38 ffffffff908c1c30 > [ 7193.961785] ffff880000000001 ffffffff8919ff21 0000000000000000 ffff8800a6fd8340 > [ 7193.961785] 0000000000000000 ffff8800a6fd8340 ffff8800a6fd8350 0000000000000282 > [ 7193.961785] Call Trace: > [ 7193.961785] lock_acquire (./arch/x86/include/asm/current.h:14 kernel/locking/lockdep.c:3602) > [ 7193.961785] ? shrink_dentry_list (fs/dcache.c:550 fs/dcache.c:781) > [ 7193.961785] _raw_spin_lock (include/linux/spinlock_api_smp.h:143 kernel/locking/spinlock.c:151) > [ 7193.961785] ? shrink_dentry_list (fs/dcache.c:550 fs/dcache.c:781) > [ 7193.961785] ? rcu_read_lock (include/linux/rcupdate.h:870 (discriminator 2)) > [ 7193.961785] shrink_dentry_list (fs/dcache.c:550 fs/dcache.c:781) > [ 7193.961785] prune_dcache_sb (fs/dcache.c:934) > [ 7193.961785] super_cache_scan (fs/super.c:94) > [ 7193.961785] shrink_slab_node (mm/vmscan.c:312) > [ 7193.961785] ? mem_cgroup_iter (mm/memcontrol.c:1258) > [ 7193.961785] ? mem_cgroup_iter (include/linux/rcupdate.h:867 mm/memcontrol.c:1222) > [ 7193.961785] shrink_slab (mm/vmscan.c:387) > [ 7193.961785] kswapd_shrink_zone (mm/vmscan.c:3028) > [ 7193.961785] balance_pgdat (mm/vmscan.c:3209) > [ 7193.961785] kswapd (mm/vmscan.c:3415) > [ 7193.961785] ? bit_waitqueue (kernel/sched/wait.c:291) > [ 7193.961785] ? balance_pgdat (mm/vmscan.c:3332) > [ 7193.961785] kthread (kernel/kthread.c:210) > [ 7193.961785] ? kthread_create_on_node (kernel/kthread.c:176) > [ 7193.961785] ret_from_fork (arch/x86/kernel/entry_64.S:349) > [ 7193.961785] ? kthread_create_on_node (kernel/kthread.c:176) > [ 7193.961785] Code: 48 c7 c2 a7 0f 6f 8d 31 c0 be 3b 03 00 00 48 c7 c7 33 67 6f 8d e8 e1 51 f9 ff e9 94 04 00 00 48 85 db 0f 84 8b 04 00 00 0f 1f 00 <f0> ff 83 98 01 00 00 8b 05 2b 51 49 07 45 8b bc 24 f0 0c 00 00 > All code > ======== > 0: 48 c7 c2 a7 0f 6f 8d mov $0xffffffff8d6f0fa7,%rdx > 7: 31 c0 xor %eax,%eax > 9: be 3b 03 00 00 mov $0x33b,%esi > e: 48 c7 c7 33 67 6f 8d mov $0xffffffff8d6f6733,%rdi > 15: e8 e1 51 f9 ff callq 0xfffffffffff951fb > 1a: e9 94 04 00 00 jmpq 0x4b3 > 1f: 48 85 db test %rbx,%rbx > 22: 0f 84 8b 04 00 00 je 0x4b3 > 28: 0f 1f 00 nopl (%rax) > 2b:* f0 ff 83 98 01 00 00 lock incl 0x198(%rbx) <-- trapping instruction > 32: 8b 05 2b 51 49 07 mov 0x749512b(%rip),%eax # 0x7495163 > 38: 45 8b bc 24 f0 0c 00 mov 0xcf0(%r12),%r15d > 3f: 00 > ... > > Code starting with the faulting instruction > =========================================== > 0: f0 ff 83 98 01 00 00 lock incl 0x198(%rbx) > 7: 8b 05 2b 51 49 07 mov 0x749512b(%rip),%eax # 0x7495138 > d: 45 8b bc 24 f0 0c 00 mov 0xcf0(%r12),%r15d > 14: 00 > ... > [ 7193.961785] RIP __lock_acquire (./arch/x86/include/asm/atomic.h:92 kernel/locking/lockdep.c:3082) > [ 7193.961785] RSP <ffff88003557f848> > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>