Dear Pete, Thank you for your email with a reproducer. Am 29.05.22 um 13:42 schrieb Peter Sutton:
Compile the attached C program (gcc -lbluetooth bug.c) and execute: $ ./a.out Interrupt (^C/SIGINT) during the connect. The process should hang and the Bluetooth socket will now be in deadlock. Kernel thread stack:
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[May29 12:23] INFO: task krfcommd:902 blocked for more than 122 seconds. [ +0.000009] Tainted: P OE 5.18.0-arch1-1 #1 [ +0.000004] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ +0.000002] task:krfcommd state:D stack: 0 pid: 902 ppid: 2 flags:0x00004000 [ +0.000010] Call Trace: [ +0.000003] <TASK> [ +0.000007] __schedule+0x37c/0x11f0 [ +0.000013] ? __schedule+0x384/0x11f0 [ +0.000012] ? l2cap_chan_create+0x138/0x180 [bluetooth da0a812fd33c72f9c94149bd973bd9835fc8aa63] [ +0.000104] schedule+0x4f/0xb0 [ +0.000008] schedule_preempt_disabled+0x15/0x20 [ +0.000009] __mutex_lock.constprop.0+0x2d0/0x480 [ +0.000012] rfcomm_run+0x152/0x1900 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000018] ? ttwu_do_wakeup+0x17/0x160 [ +0.000011] ? _raw_spin_rq_lock_irqsave+0x20/0x20 [ +0.000010] ? rfcomm_check_accept+0xa0/0xa0 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000015] kthread+0xde/0x110 [ +0.000011] ? kthread_complete_and_exit+0x20/0x20 [ +0.000010] ret_from_fork+0x22/0x30 [ +0.000012] </TASK> Task stack: [ +0.000003] INFO: task a.out:1035 blocked for more than 122 seconds. [ +0.000004] Tainted: P OE 5.18.0-arch1-1 #1 [ +0.000003] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ +0.000001] task:a.out state:D stack: 0 pid: 1035 ppid: 817 flags:0x00004006 [ +0.000008] Call Trace: [ +0.000002] <TASK> [ +0.000003] __schedule+0x37c/0x11f0 [ +0.000009] ? __mod_memcg_state+0x2f/0x70 [ +0.000008] schedule+0x4f/0xb0 [ +0.000007] __lock_sock+0x7d/0xc0 [ +0.000010] ? cpuacct_percpu_seq_show+0x20/0x20 [ +0.000009] lock_sock_nested+0x48/0x50 [ +0.000009] rfcomm_sk_state_change+0x2b/0x120 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000018] __rfcomm_dlc_close+0x99/0x210 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000015] rfcomm_dlc_close+0x6e/0xb0 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000015] __rfcomm_sock_close+0x2e/0xe0 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000017] rfcomm_sock_shutdown+0x65/0xa0 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000016] rfcomm_sock_release+0x32/0xb0 [rfcomm 70c711e71e4c70ddabda45ec756f02d9606ec257] [ +0.000016] __sock_release+0x3d/0xa0 [ +0.000010] sock_close+0x15/0x20 [ +0.000009] __fput+0x89/0x240 [ +0.000011] task_work_run+0x60/0x90 [ +0.000007] do_exit+0x337/0xac0 [ +0.000010] ? del_timer_sync+0x73/0xb0 [ +0.000006] do_group_exit+0x31/0xa0 [ +0.000009] get_signal+0x986/0x990 [ +0.000007] ? bt_sock_wait_state+0x124/0x1a0 [bluetooth da0a812fd33c72f9c94149bd973bd9835fc8aa63] [ +0.000060] ? wake_up_q+0x90/0x90 [ +0.000010] arch_do_signal_or_restart+0x48/0x760 [ +0.000012] exit_to_user_mode_prepare+0xd3/0x140 [ +0.000008] syscall_exit_to_user_mode+0x26/0x50 [ +0.000006] do_syscall_64+0x6b/0x90 [ +0.000009] ? exc_page_fault+0x74/0x170 [ +0.000009] entry_SYSCALL_64_after_hwframe+0x44/0xae [ +0.000007] RIP: 0033:0x7f4ab4f13557 [ +0.000006] RSP: 002b:00007fff5b37cc38 EFLAGS: 00000246 ORIG_RAX: 000000000000002a [ +0.000007] RAX: fffffffffffffffc RBX: 00007fff5b37cd78 RCX: 00007f4ab4f13557 [ +0.000004] RDX: 000000000000000a RSI: 00007fff5b37cc4e RDI: 0000000000000003 [ +0.000004] RBP: 00007fff5b37cc60 R08: 0fffffffffffffff R09: 0000000000000000 [ +0.000003] R10: 00007f4ab4e075e0 R11: 0000000000000246 R12: 0000000000000000 [ +0.000003] R13: 00007fff5b37cd88 R14: 0000562da1cefde0 R15: 00007f4ab5214000 [ +0.000007] </TASK> Process stack: [<0>] __lock_sock+0x7d/0xc0 [<0>] lock_sock_nested+0x48/0x50 [<0>] rfcomm_sk_state_change+0x2b/0x120 [rfcomm] [<0>] __rfcomm_dlc_close+0x99/0x210 [rfcomm] [<0>] rfcomm_dlc_close+0x6e/0xb0 [rfcomm] [<0>] __rfcomm_sock_close+0x2e/0xe0 [rfcomm] [<0>] rfcomm_sock_shutdown+0x65/0xa0 [rfcomm] [<0>] rfcomm_sock_release+0x32/0xb0 [rfcomm] [<0>] __sock_release+0x3d/0xa0 [<0>] sock_close+0x15/0x20 [<0>] __fput+0x89/0x240 [<0>] task_work_run+0x60/0x90 [<0>] do_exit+0x337/0xac0 [<0>] do_group_exit+0x31/0xa0 [<0>] get_signal+0x986/0x990 [<0>] arch_do_signal_or_restart+0x48/0x760 [<0>] exit_to_user_mode_prepare+0xd3/0x140 [<0>] syscall_exit_to_user_mode+0x26/0x50 [<0>] do_syscall_64+0x6b/0x90 [<0>] entry_SYSCALL_64_after_hwframe+0x44/0xae Replicated by Matt (CC'ed running 5.15.39) on different hardware and Lloyd (CC'ed) on same hardware with same stack trace. Tested on up-to-date Arch Linux (5.18.0).
What hardware is that?
Let me know if you need anything else.
As a lot of patches are also applied to the stable series, do you know, if this is a regression? Does it work with Linux 5.15(.0) or 5.10?
Kind regards, Paul
-- Pete.
Only, if you care, the standard signature delimiter has a trailing space: `-- ` [1].
[1]: https://en.wikipedia.org/wiki/Signature_block#Standard_delimiter
