Hello,

syzbot found the following issue on:

HEAD commit: e01d50cbd6ee Merge tag 'vfio-v6.1-rc6' of https://github.c.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=145f6401880000 kernel config: https://syzkaller.appspot.com/x/.config?x=e9039cbe1d7613aa dashboard link: https://syzkaller.appspot.com/bug?extid=65422ff0767f378aacfb compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/43fe73693a6c/disk-e01d50cb.raw.... vmlinux: https://storage.googleapis.com/syzbot-assets/35e1240adbc1/vmlinux-e01d50cb.x... kernel image: https://storage.googleapis.com/syzbot-assets/3b532cce5d0b/bzImage-e01d50cb.x...

IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+65422ff0767f378aacfb@syzkaller.appspotmail.com

================================ WARNING: inconsistent lock state 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0 Not tainted -------------------------------- inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. syz-executor.4/7818 [HC0[0]:SC0[0]:HE0:SE1] takes: ffffffff8cb76bb8 (sync_timeline_list_lock){?...}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] ffffffff8cb76bb8 (sync_timeline_list_lock){?...}-{2:2}, at: sync_info_debugfs_show+0x2d/0x200 drivers/dma-buf/sync_debug.c:147 {IN-HARDIRQ-W} state was registered at: lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 sync_timeline_debug_remove+0x25/0x190 drivers/dma-buf/sync_debug.c:31 sync_timeline_free drivers/dma-buf/sw_sync.c:104 [inline] kref_put include/linux/kref.h:65 [inline] sync_timeline_put drivers/dma-buf/sw_sync.c:116 [inline] timeline_fence_release+0x263/0x340 drivers/dma-buf/sw_sync.c:144 dma_fence_release+0x147/0x680 drivers/dma-buf/dma-fence.c:559 kref_put include/linux/kref.h:65 [inline] dma_fence_put include/linux/dma-fence.h:276 [inline] dma_fence_array_release+0x1f6/0x2d0 drivers/dma-buf/dma-fence-array.c:120 dma_fence_release+0x147/0x680 drivers/dma-buf/dma-fence.c:559 kref_put include/linux/kref.h:65 [inline] dma_fence_put include/linux/dma-fence.h:276 [inline] irq_dma_fence_array_work+0xa5/0xd0 drivers/dma-buf/dma-fence-array.c:52 irq_work_single+0x120/0x250 kernel/irq_work.c:211 irq_work_run_list kernel/irq_work.c:242 [inline] irq_work_run_list+0x91/0xc0 kernel/irq_work.c:225 irq_work_run+0x54/0xd0 kernel/irq_work.c:251 __sysvec_irq_work+0xca/0x4d0 arch/x86/kernel/irq_work.c:22 sysvec_irq_work+0x8e/0xc0 arch/x86/kernel/irq_work.c:17 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:675 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202 spin_unlock_irq include/linux/spinlock.h:400 [inline] sw_sync_debugfs_release+0x15e/0x230 drivers/dma-buf/sw_sync.c:321 __fput+0x27c/0xa90 fs/file_table.c:320 task_work_run+0x16b/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xb35/0x2a20 kernel/exit.c:820 do_group_exit+0xd0/0x2a0 kernel/exit.c:950 get_signal+0x21a1/0x2430 kernel/signal.c:2858 arch_do_signal_or_restart+0x82/0x2300 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x15f/0x250 kernel/entry/common.c:203 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:296 ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:299 irq event stamp: 288 hardirqs last enabled at (287): [<ffffffff81d0a451>] mod_objcg_state+0x591/0xa50 mm/memcontrol.c:3213 hardirqs last disabled at (288): [<ffffffff89922691>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline] hardirqs last disabled at (288): [<ffffffff89922691>] _raw_spin_lock_irq+0x41/0x50 kernel/locking/spinlock.c:170 softirqs last enabled at (0): [<ffffffff8146e349>] copy_process+0x2129/0x7190 kernel/fork.c:2198 softirqs last disabled at (0): [<0000000000000000>] 0x0

other info that might help us debug this: Possible unsafe locking scenario:

CPU0 ---- lock(sync_timeline_list_lock); <Interrupt> lock(sync_timeline_list_lock);

*** DEADLOCK ***

3 locks held by syz-executor.4/7818: #0: ffff8880412b59e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe3/0x100 fs/file.c:1037 #1: ffff888017a97418 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xdf/0x1280 fs/seq_file.c:182 #2: ffffffff8cb76bb8 (sync_timeline_list_lock){?...}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] #2: ffffffff8cb76bb8 (sync_timeline_list_lock){?...}-{2:2}, at: sync_info_debugfs_show+0x2d/0x200 drivers/dma-buf/sync_debug.c:147

stack backtrace: CPU: 0 PID: 7818 Comm: syz-executor.4 Not tainted 6.1.0-rc5-syzkaller-00008-ge01d50cbd6ee #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_usage_bug kernel/locking/lockdep.c:3963 [inline] valid_state kernel/locking/lockdep.c:3975 [inline] mark_lock_irq kernel/locking/lockdep.c:4178 [inline] mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4634 mark_lock kernel/locking/lockdep.c:4598 [inline] mark_held_locks+0x9f/0xe0 kernel/locking/lockdep.c:4236 __trace_hardirqs_on_caller kernel/locking/lockdep.c:4254 [inline] lockdep_hardirqs_on_prepare kernel/locking/lockdep.c:4321 [inline] lockdep_hardirqs_on_prepare+0x135/0x400 kernel/locking/lockdep.c:4273 trace_hardirqs_on+0x2d/0x160 kernel/trace/trace_preemptirq.c:49 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline] _raw_spin_unlock_irq+0x1f/0x40 kernel/locking/spinlock.c:202 spin_unlock_irq include/linux/spinlock.h:400 [inline] sync_print_obj drivers/dma-buf/sync_debug.c:118 [inline] sync_info_debugfs_show+0xeb/0x200 drivers/dma-buf/sync_debug.c:153 seq_read_iter+0x4f5/0x1280 fs/seq_file.c:230 seq_read+0x16d/0x210 fs/seq_file.c:162 vfs_read+0x257/0x930 fs/read_write.c:468 ksys_read+0x127/0x250 fs/read_write.c:613 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f8c5028b639 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8c4f5ff168 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f8c503ac1f0 RCX: 00007f8c5028b639 RDX: 0000000000002020 RSI: 0000000020001a00 RDI: 000000000000000b RBP: 00007f8c502e6ae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f8c504cfb1f R14: 00007f8c4f5ff300 R15: 0000000000022000 </TASK>

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