Messages in this thread Patch in this message | | | Date | Thu, 12 Jan 2023 22:45:55 -0800 | Subject | Re: WARNING in debug_mutex_unlock | From | Yonghong Song <> |
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On 1/8/23 11:44 PM, Hao Sun wrote: > Hi, > > The following warning can be triggered with the C reproducer in > the link. The repro starts 32 threads, each attaches a tracepoint > into `ext4_mark_inode_dirty`. The prog loads the following insns > that simply sends signal to current proc, and then wait. > > Seems issues in queued irq_work with `do_bpf_send_signal`, also > I'm wondering what if the task in `send_signal_irq_work` exited, > at the time the callback invoked.
Somehow, I cannot reproduce the issue in my qemu environment with below kernel config and C reproducer.
But could you try the following patch to see whether it fixed the issue in your environment?
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 23ce498bca97..1b26d51caf31 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -831,6 +831,7 @@ static void do_bpf_send_signal(struct irq_work *entry)
work = container_of(entry, struct send_signal_irq_work, irq_work); group_send_sig_info(work->sig, SEND_SIG_PRIV, work->task, work->type); + put_task_struct(work->task); }
static int bpf_send_signal_common(u32 sig, enum pid_type type) @@ -862,7 +863,7 @@ static int bpf_send_signal_common(u32 sig, enum pid_type type) * to the irq_work. The current task may change when queued * irq works get executed. */ - work->task = current; + work->task = get_task_struct(current); work->sig = sig; work->type = type; irq_work_queue(&work->irq_work); > > This can be reproduced on: > > HEAD commit: 6d0c4b11e743 ("libbpf: Poison strlcpy()") > git tree: bpf-next > console output: https://pastebin.com/raw/ZtVM15Jx > kernel config : https://pastebin.com/raw/nt6XW0Sz > C reproducer : https://pastebin.com/raw/NHqy5tR6 > > func#0 @0 > 0: R1=ctx(off=0,imm=0) R10=fp0 > 0: (18) r0 = 0x0 ; R0_w=0 > 2: (18) r6 = 0x0 ; R6_w=0 > 4: (18) r7 = 0x0 ; R7_w=0 > 6: (18) r8 = 0x0 ; R8_w=0 > 8: (18) r9 = 0x0 ; R9_w=0 > 10: (18) r1 = 0x700000007 ; R1_w=30064771079 > 12: (85) call bpf_send_signal#109 ; R0_w=scalar() > 13: (95) exit > processed 8 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0 > > ------------[ cut here ]------------ > DEBUG_LOCKS_WARN_ON(lock->magic != lock) > WARNING: CPU: 3 PID: 41309 at kernel/locking/mutex-debug.c:74 debug_mutex_unlock+0x1fc/0x250 kernel/locking/mutex-debug.c:74 > Modules linked in: > CPU: 3 PID: 41309 Comm: systemd-udevd Not tainted 6.2.0-rc2-00302-g6d0c4b11e743 #153 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 > RIP: 0010:debug_mutex_unlock+0x1fc/0x250 kernel/locking/mutex-debug.c:74 > Code: 84 c0 75 59 8b 15 34 92 3a 11 85 d2 0f 84 c5 fe ff ff e9 e6 fe ff ff 48 c7 c6 a0 50 4c 8a 48 c7 c7 a0 4e 4c 8a e8 9e bb 5f 08 <0f> 0b eb b2 e8 bb 9d 6e 00 e9 be fe ff ff e8 b1 9d 6e 00 e9 8b fe > RSP: 0018:ffffc90012b7f6f8 EFLAGS: 00010286 > RAX: 0000000000000000 RBX: ffff88804145a2d0 RCX: 0000000000000000 > RDX: ffff88803f468000 RSI: ffffffff81671400 RDI: fffff5200256fed1 > RBP: ffffffff929e2a00 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000080000001 R11: ffffffff90d3f0c3 R12: ffff88804145a2d8 > R13: fffffbfff253c540 R14: ffffffff929e2a00 R15: ffffc90012b7f798 > FS: 00007f36a937e8c0(0000) GS:ffff888135c80000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000056181882c020 CR3: 000000002a9a2000 CR4: 0000000000750ee0 > PKRU: 55555554 > Call Trace: > <TASK> > __mutex_unlock_slowpath+0x197/0x630 kernel/locking/mutex.c:933 > devlink_compat_running_version+0x128/0x6c0 net/devlink/leftover.c:12237 > dev_ethtool+0x55f/0x53c0 net/ethtool/ioctl.c:3091 > dev_ioctl+0x29e/0x1050 net/core/dev_ioctl.c:524 > sock_do_ioctl+0x1be/0x250 net/socket.c:1183 > sock_ioctl+0x205/0x6a0 net/socket.c:1286 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl fs/ioctl.c:856 [inline] > __x64_sys_ioctl+0x189/0x210 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7f36a94a55f7 > Code: 00 00 00 48 8b 05 99 c8 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 69 c8 0d 00 f7 d8 64 89 01 48 > RSP: 002b:00007ffd663b3d98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 00005618188043f0 RCX: 00007f36a94a55f7 > RDX: 00007ffd663b3e60 RSI: 0000000000008946 RDI: 0000000000000006 > RBP: 00007ffd663b3e90 R08: 0000561818887fa0 R09: 0000000000000000 > R10: 00007f36a937e6c0 R11: 0000000000000246 R12: 0000561818887fa0 > R13: 0000561818832c70 R14: 00007ffd663b3e60 R15: 0000000000000007 > </TASK> >
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