Hi, On Wed, Oct 16, 2019 at 02:27:07AM -0700, syzbot wrote: > syzbot has found a reproducer for the following crash on: > > HEAD commit: 0e9d28bc Add linux-next specific files for 20191015 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=11745608e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=3d84ca04228b0bf4 > dashboard link: https://syzkaller.appspot.com/bug?extid=36baa6c2180e959e19b1 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=159d297f600000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16289b30e00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+36baa6c2180e959e19b1@xxxxxxxxxxxxxxxxxxxxxxxxx > > ===================================== > WARNING: bad unlock balance detected! > 5.4.0-rc3-next-20191015 #0 Not tainted > ------------------------------------- > syz-executor276/8897 is trying to release lock (rcu_callback) at: > [<ffffffff8160e7a4>] __write_once_size include/linux/compiler.h:226 [inline] > [<ffffffff8160e7a4>] __rcu_reclaim kernel/rcu/rcu.h:221 [inline] > [<ffffffff8160e7a4>] rcu_do_batch kernel/rcu/tree.c:2157 [inline] > [<ffffffff8160e7a4>] rcu_core+0x574/0x1560 kernel/rcu/tree.c:2377 > but there are no more locks to release! > > other info that might help us debug this: > 1 lock held by syz-executor276/8897: > #0: ffff88809a3cc0d8 (&type->s_umount_key#40/1){+.+.}, at: > alloc_super+0x158/0x910 fs/super.c:229 > > stack backtrace: > CPU: 0 PID: 8897 Comm: syz-executor276 Not tainted 5.4.0-rc3-next-20191015 > #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > <IRQ> > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x172/0x1f0 lib/dump_stack.c:113 > print_unlock_imbalance_bug kernel/locking/lockdep.c:4008 [inline] > print_unlock_imbalance_bug.cold+0x114/0x123 kernel/locking/lockdep.c:3984 > __lock_release kernel/locking/lockdep.c:4244 [inline] > lock_release+0x5f2/0x960 kernel/locking/lockdep.c:4505 > rcu_lock_release include/linux/rcupdate.h:213 [inline] > __rcu_reclaim kernel/rcu/rcu.h:223 [inline] I have little knowledge about this kind of stuff, but after seeing the dashboard https://syzkaller.appspot.com/bug?extid=36baa6c2180e959e19b1 I guess this is highly related with ntfs, and in ntfs_fill_super, it has lockdep_off() in ntfs_fill_super... In detail, commit 90c1cba2b3b3 ("locking/lockdep: Zap lock classes even with lock debugging disabled") [1], and free_zapped_rcu.... static void free_zapped_rcu(struct rcu_head *ch) { struct pending_free *pf; unsigned long flags; if (WARN_ON_ONCE(ch != &delayed_free.rcu_head)) return; raw_local_irq_save(flags); arch_spin_lock(&lockdep_lock); current->lockdep_recursion = 1; <--- here /* closed head */ pf = delayed_free.pf + (delayed_free.index ^ 1); __free_zapped_classes(pf); delayed_free.scheduled = false; /* * If there's anything on the open list, close and start a new callback. */ call_rcu_zapped(delayed_free.pf + delayed_free.index); current->lockdep_recursion = 0; arch_spin_unlock(&lockdep_lock); raw_local_irq_restore(flags); } Completely guess and untest since I am not familar with that, but in case of that, Cc related people... If I'm wrong, ignore my comments and unintentional noise.... [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=90c1cba2b3b3851c151229f61801919b2904d437 Thanks, Gao Xiang > rcu_do_batch kernel/rcu/tree.c:2157 [inline] > rcu_core+0x594/0x1560 kernel/rcu/tree.c:2377 > rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386 > __do_softirq+0x262/0x98c kernel/softirq.c:292 > invoke_softirq kernel/softirq.c:373 [inline] > irq_exit+0x19b/0x1e0 kernel/softirq.c:413 > exiting_irq arch/x86/include/asm/apic.h:536 [inline] > smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137 > apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830 > </IRQ> > RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:756 > [inline] > RIP: 0010:console_unlock+0xbb8/0xf00 kernel/printk/printk.c:2481 > Code: f3 88 48 c1 e8 03 42 80 3c 30 00 0f 85 e4 02 00 00 48 83 3d 99 9c 96 > 07 00 0f 84 91 01 00 00 e8 be c4 16 00 48 8b 7d 98 57 9d <0f> 1f 44 00 00 e9 > 6d ff ff ff e8 a9 c4 16 00 48 8b 7d 08 c7 05 eb > RSP: 0018:ffff88809fd7f8f0 EFLAGS: 00000293 ORIG_RAX: ffffffffffffff13 > RAX: ffff8880a8bee540 RBX: 0000000000000200 RCX: 1ffffffff138eea6 > RDX: 0000000000000000 RSI: ffffffff815c8592 RDI: 0000000000000293 > RBP: ffff88809fd7f978 R08: ffff8880a8bee540 R09: fffffbfff11f4119 > R10: fffffbfff11f4118 R11: 0000000000000001 R12: 0000000000000000 > R13: ffffffff843f8ca0 R14: dffffc0000000000 R15: ffffffff895e1130 > vprintk_emit+0x2a0/0x700 kernel/printk/printk.c:1996 > vprintk_default+0x28/0x30 kernel/printk/printk.c:2023 > vprintk_func+0x7e/0x189 kernel/printk/printk_safe.c:386 > printk+0xba/0xed kernel/printk/printk.c:2056 > __ntfs_error.cold+0x91/0xc7 fs/ntfs/debug.c:89 > read_ntfs_boot_sector fs/ntfs/super.c:682 [inline] > ntfs_fill_super+0x1ad3/0x3160 fs/ntfs/super.c:2784 > mount_bdev+0x304/0x3c0 fs/super.c:1415 > ntfs_mount+0x35/0x40 fs/ntfs/super.c:3051 > legacy_get_tree+0x108/0x220 fs/fs_context.c:647 > vfs_get_tree+0x8e/0x300 fs/super.c:1545 > do_new_mount fs/namespace.c:2823 [inline] > do_mount+0x142e/0x1cf0 fs/namespace.c:3143 > ksys_mount+0xdb/0x150 fs/namespace.c:3352 > __do_sys_mount fs/namespace.c:3366 [inline] > __se_sys_mount fs/namespace.c:3363 [inline] > __x64_sys_mount+0xbe/0x150 fs/namespace.c:3363 > do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x4411a9 > Code: e8 fc ab 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff > 0f 83 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007ffffff57cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004411a9 > RDX: 0000000020000140 RSI: 0000000020000280 RDI: 00000000200004c0 > RBP: 00000000000114e0 R08: 0000000000000000 R09: 00000000004002c8 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401fd0 > R13: 0000000000402060 R14: 0000000000000000 R15: 0000000000000000 >
