Subject: Re: BUG: using smp_processor_id() in preemptible

From: Eric Dumazet <[email-masked]>
Date: Thu, 11 Jan 2018 09:14:10 -0800

On Thu, 2018-01-11 at 10:31 -0200, Ricardo Nabinger Sanchez wrote:
> Greetings,
> 
> I'm getting occasional video lock-ups, and while checking logs I found
> these:
> 
> ===
> [  297.445296] BUG: using smp_processor_id() in preemptible [00000000] code: claws-mail/1635
> [  297.445319] caller is jprobe_return+0x12/0x25
> [  297.445332] CPU: 1 PID: 1635 Comm: claws-mail Not tainted 4.14.0 #1
> [  297.445341] Hardware name: Micro-Star International Co., Ltd. GX780/GT780/MS-1761, BIOS E1761IMS V3.01 05/02/2011
> [  297.445349] Call Trace:
> [  297.445372]  dump_stack+0x9f/0xe1
> [  297.445392]  check_preemption_disabled+0xec/0xf0
> [  297.445409]  jprobe_return+0x12/0x25
> [  297.445425]  tcp_v4_do_rcv+0x7f/0x1a0
> [  297.445443]  __release_sock+0x6d/0x100
> [  297.445462]  release_sock+0x2b/0xb0
> [  297.445475]  tcp_recvmsg+0x300/0x8f0
> [  297.445504]  ? __lock_acquire+0x3ee/0x1610
> [  297.445517]  ? core_sys_select+0x240/0x3e0
> [  297.445541]  inet_recvmsg+0x51/0x1b0
> [  297.445566]  sock_read_iter+0x8c/0xd0
> [  297.445598]  __vfs_read+0xd5/0x140
> [  297.445632]  vfs_read+0x9e/0x150
> [  297.445652]  SyS_read+0x45/0xa0
> [  297.445675]  entry_SYSCALL_64_fastpath+0x23/0xc2
> [  297.445687] RIP: 0033:0x7ff2536001b8
> [  297.445696] RSP: 002b:00007ff247152890 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> [  297.445713] RAX: ffffffffffffffda RBX: ffff9cd088ccbff0 RCX: 00007ff2536001b8
> [  297.445721] RDX: 0000000000000005 RSI: 00007ff23c02bb43 RDI: 0000000000000013
> [  297.445730] RBP: 00007ff23c02bb43 R08: 0000000000000000 R09: 00007ff23c00e520
> [  297.445738] R10: 0000000000100000 R11: 0000000000000246 R12: 0000000000000086
> [  297.445746] R13: 000000000000002f R14: 00007ff254d3c998 R15: 0000000000000001
> ...
> [  366.965766] BUG: using smp_processor_id() in preemptible [00000000] code: Socket Thread/1435
> [  366.965769] caller is jprobe_return+0x12/0x25
> [  366.965773] CPU: 0 PID: 1435 Comm: Socket Thread Not tainted 4.14.0 #1
> [  366.965775] Hardware name: Micro-Star International Co., Ltd. GX780/GT780/MS-1761, BIOS E1761IMS V3.01 05/02/2011
> [  366.965777] Call Trace:
> [  366.965780]  dump_stack+0x9f/0xe1
> [  366.965786]  check_preemption_disabled+0xec/0xf0
> [  366.965790]  jprobe_return+0x12/0x25
> [  366.965793]  tcp_v4_do_rcv+0x7f/0x1a0
> [  366.965797]  __release_sock+0x6d/0x100
> [  366.965811]  release_sock+0x2b/0xb0
> [  366.965813]  tcp_recvmsg+0x300/0x8f0
> [  366.965826]  inet_recvmsg+0x51/0x1b0
> [  366.965834]  SYSC_recvfrom+0xc6/0x130
> [  366.965845]  ? entry_SYSCALL_64_fastpath+0x5/0xc2
> [  366.965848]  ? trace_hardirqs_on_caller+0xcb/0x200
> [  366.965851]  ? trace_hardirqs_on_thunk+0x1a/0x1c
> [  366.965858]  entry_SYSCALL_64_fastpath+0x23/0xc2
> [  366.965860] RIP: 0033:0x7f475ab7e5da
> [  366.965862] RSP: 002b:00007f47438fc8b0 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
> [  366.965864] RAX: ffffffffffffffda RBX: ffff9cd088ae7ff0 RCX: 00007f475ab7e5da
> [  366.965865] RDX: 0000000000008000 RSI: 00007f4721202000 RDI: 000000000000007c
> [  366.965867] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> [  366.965868] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000086
> [  366.965869] R13: 00007f47212025a8 R14: 0000000000007a58 R15: 00007f474ba1e5f2
> [  366.966571] BUG: using smp_processor_id() in preemptible [00000000] code: Socket Thread/1435
> [  366.966574] caller is jprobe_return+0x12/0x25
> [  366.966576] CPU: 0 PID: 1435 Comm: Socket Thread Not tainted 4.14.0 #1
> [  366.966577] Hardware name: Micro-Star International Co., Ltd. GX780/GT780/MS-1761, BIOS E1761IMS V3.01 05/02/2011
> [  366.966578] Call Trace:
> [  366.966582]  dump_stack+0x9f/0xe1
> [  366.966586]  check_preemption_disabled+0xec/0xf0
> [  366.966592]  jprobe_return+0x12/0x25
> [  366.966596]  tcp_v4_do_rcv+0x7f/0x1a0
> [  366.966601]  __release_sock+0x6d/0x100
> [  366.966606]  release_sock+0x2b/0xb0
> [  366.966610]  tcp_recvmsg+0x300/0x8f0
> [  366.966622]  inet_recvmsg+0x51/0x1b0
> [  366.966630]  SYSC_recvfrom+0xc6/0x130
> [  366.966643]  ? entry_SYSCALL_64_fastpath+0x5/0xc2
> [  366.966647]  ? trace_hardirqs_on_caller+0xcb/0x200
> [  366.966651]  ? trace_hardirqs_on_thunk+0x1a/0x1c
> [  366.966667]  entry_SYSCALL_64_fastpath+0x23/0xc2
> [  366.966669] RIP: 0033:0x7f475ab7e5da
> [  366.966670] RSP: 002b:00007f47438fc8b0 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
> [  366.966673] RAX: ffffffffffffffda RBX: ffff9cd088ae7ff0 RCX: 00007f475ab7e5da
> [  366.966674] RDX: 0000000000008000 RSI: 00007f4721202000 RDI: 000000000000007c
> [  366.966676] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> [  366.966677] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000086
> [  366.966679] R13: 00007f47438fca70 R14: 00000000000005a8 R15: 00007f4721202000
> [  366.979991] BUG: using smp_processor_id() in preemptible [00000000] code: Socket Thread/1435
> [  366.979999] caller is jprobe_return+0x12/0x25
> [  366.980004] CPU: 0 PID: 1435 Comm: Socket Thread Not tainted 4.14.0 #1
> [  366.980007] Hardware name: Micro-Star International Co., Ltd. GX780/GT780/MS-1761, BIOS E1761IMS V3.01 05/02/2011
> [  366.980012] Call Trace:
> [  366.980023]  dump_stack+0x9f/0xe1
> [  366.980033]  check_preemption_disabled+0xec/0xf0
> [  366.980040]  jprobe_return+0x12/0x25
> [  366.980046]  tcp_v4_do_rcv+0x7f/0x1a0
> [  366.980054]  __release_sock+0x6d/0x100
> [  366.980062]  release_sock+0x2b/0xb0
> [  366.980068]  tcp_recvmsg+0x300/0x8f0
> [  366.980105]  inet_recvmsg+0x51/0x1b0
> [  366.980117]  SYSC_recvfrom+0xc6/0x130
> [  366.980130]  ? entry_SYSCALL_64_fastpath+0x5/0xc2
> [  366.980134]  ? trace_hardirqs_on_caller+0xcb/0x200
> [  366.980137]  ? trace_hardirqs_on_thunk+0x1a/0x1c
> [  366.980145]  entry_SYSCALL_64_fastpath+0x23/0xc2
> [  366.980147] RIP: 0033:0x7f475ab7e5da
> [  366.980149] RSP: 002b:00007f47438fc8b0 EFLAGS: 00000246 ORIG_RAX: 000000000000002d
> [  366.980152] RAX: ffffffffffffffda RBX: ffff9cd088ae7ff0 RCX: 00007f475ab7e5da
> [  366.980154] RDX: 0000000000008000 RSI: 00007f4721202000 RDI: 000000000000007c
> [  366.980157] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> [  366.980158] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000086
> [  366.980161] R13: 0000000000008000 R14: 00007f47438fca70 R15: 00007f474ba1e5f2
> ===
> 
> There are many of those, and they keep popping up throughout normal
> usage.  Sometimes, though, things go awry but without much information:
> 
> ===
> Jan 10 17:54:39 kernel: [ 2717.421681] note: Socket Thread[1812] exited with preempt_count 1
> ===
> 
> It seems that when the event above happens (preempt_count 1), a chain of
> events unfolds and my video locks up.  Sometimes the mouse pointer will
> continue to work; others it is a full lockup.
> 
> I understand this is not necessarily linked to the network stack, but as it
> happens, the traces always have the network stack in common and the application
> that exits has always been one that deals with network (Firefox and Claws
> Mail so far).
> 
> This has been happening for quite a while now, at least since 4.9 (probably
> before that).  I don't know how to trigger this: it could take as much as
> 45 days to "lock up" or as little as a few minutes in sequence.  Yesterday,
> the first time it locked up took around 20 days, and then less than 10 minutes.
> 
> 
> The best information I have are dumps from SysRq:
> ===
> Jan 10 17:54:39 darkbook kernel: [ 2717.421681] note: Socket Thread[1812] exited with preempt_count 1
> Jan 10 17:55:45 darkbook acpid: client 1084[0:100] has disconnected
> Jan 10 17:55:46 darkbook /usr/sbin/gpm[970]: *** info [mice.c(1990)]: 
> Jan 10 17:55:46 darkbook /usr/sbin/gpm[970]: imps2: Auto-detected intellimouse PS/2
> Jan 10 17:56:12 darkbook kernel: [ 2811.376514] sysrq: SysRq : Show Locks Held
> Jan 10 17:56:14 darkbook kernel: [ 2813.214132] sysrq: SysRq : Show backtrace of all active CPUs
> Jan 10 17:56:14 darkbook kernel: [ 2813.215131] Sending NMI from CPU 0 to CPUs 1-7:
> Jan 10 17:56:16 darkbook kernel: [ 2814.975638] sysrq: SysRq : Show Blocked State
> Jan 10 17:56:16 darkbook kernel: [ 2814.975679]   task                        PC stack   pid father
> Jan 10 17:56:20 darkbook kernel: [ 2819.060962] localStorage DB S    0  1884   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.061483] LoadRoots       S    0  1900   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.061970] SysProxySetting S    0  1901   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.062477] dconf worker    S    0  1902   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.063222] ProxyResolution S    0  1903   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.063727] DataStorage     S    0  1904   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.064175] URL Classifier  S    0  1905   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.064680] Classif~ Update S    0  1906   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.065182] DataStorage     S    0  1908   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.065718] DataStorage     S    0  1909   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.066151] SaveScripts     S    0  1910   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.066684] Cache I/O       S    0  1911   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.067149] mozStorage #1   S    0  1913   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.067693] mozStorage #2   S    0  1916   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.068222] QuotaManager IO S    0  1917   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.068721] mozStorage #3   S    0  1918   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.069210] mozStorage #4   S    0  1919   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.069714] mozStorage #5   S    0  1922   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.070242] DOM Worker      S    0  1923   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.070743] DOM Worker      S    0  1947   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.071272] IdentityCrypto  S    0  1967   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.071799] mozStorage #7   S    0  1976   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.072267] mozStorage #8   S    0  1978   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.072775] DNS Resolver #7 S    0  2265   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.073256] DNS Resolver #9 S    0  2860   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.073763] DNS Res~ver #10 S    0  2861   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.074266] DNS Res~ver #11 S    0  2862   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.074765] speechd init    S    0  2894   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.075268] BgFileSaver     S    0  2916   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.075779] mozStorage #9   S    0  2919   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.076270] DOMCacheThread  S    0  2939   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.076793] Web Content     S    0  1852   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.077632] Chrome_~dThread S    0  1855   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.078069] JS Watchdog     S    0  1858   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.078634] JS Helper       S    0  1859   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.079164] JS Helper       S    0  1860   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.079689] JS Helper       S    0  1861   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.080219] JS Helper       S    0  1862   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.080785] JS Helper       S    0  1863   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.081369] JS Helper       S    0  1864   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.081901] JS Helper       S    0  1865   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.082450] JS Helper       S    0  1866   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.082964] JS Helper       S    0  1867   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.083507] JS Helper       S    0  1868   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.084043] JS Helper       S    0  1869   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.084610] JS Helper       S    0  1870   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.085146] Socket Thread   S    0  1871   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.085872] Hang Monitor    S    0  1872   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.086379] Timer           S    0  1873   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.086886] ImgDecoder #1   S    0  1874   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.087411] ImgDecoder #2   S    0  1875   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.087960] ImgDecoder #3   S    0  1876   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.088527] ImgDecoder #4   S    0  1877   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.089036] ImgDecoder #5   S    0  1878   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.089578] ImgDecoder #6   S    0  1879   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.090130] ImgDecoder #7   S    0  1880   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.090673] ImageIO         S    0  1881   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.091220] ImageBr~geChild S    0  1882   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.092005] VideoChild      S    0  1883   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.092782] threaded-ml     S    0  1887   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.093679] ProcessHangMon  S    0  1888   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.094371] ProfilerChild   S    0  1889   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.094984] gmain           S    0  1890   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.095822] gdbus           S    0  1891   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.096438] StyleThread#0   S    0  1893   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.096909] StyleThread#1   S    0  1894   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.097453] StyleThread#2   S    0  1895   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.098059] StyleThread#3   S    0  1896   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.098717] StyleThread#4   S    0  1897   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.099407] StyleThread#5   S    0  1898   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.100011] HTML5 Parser    S    0  1914   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.100616] dconf worker    S    0  1979   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.101536] MediaPl~ack #13 S    0  2853   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.102052] MediaPl~ack #14 S    0  2854   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.102605] DOM Worker      S    0  2889   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.103124] DOM Worker      S    0  2893   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.103708] MediaTimer #3   S    0  2898   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.104244] MediaPl~ack #17 S    0  2900   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.104802] MediaPl~ack #18 S    0  2901   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.105328] MediaPD~oder #6 S    0  2902   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.105835] MediaPD~oder #7 S    0  2903   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.106378] MediaPD~oder #8 S    0  2904   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.106883] MediaPD~oder #9 S    0  2905   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.107405] DOM Worker      S    0  2938   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.107937] SubtleCrypto #1 S    0  2947   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.108457] StreamTrans #16 S    0  2954   1809 0x00000100
> Jan 10 17:56:20 darkbook kernel: [ 2819.109021] fish            S    0  2165   1422 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.109522] ssh             S    0  2214   2165 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.110386] kworker/0:4     I    0  2327      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.110599] xfrun4          S    0  2329   1127 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.111390] gmain           S    0  2330   1127 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.112123] gdbus           S    0  2331   1127 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.112797] xmms            S    0  2337   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.113584] xmms            S    0  2338   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.114426] xmms            S    0  2339   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.114842] xmms            S    0  2340   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.115265] xmms            S    0  2345   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.116489] xmms            S    0  2847   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.117433] threaded-ml     S    0  2848   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.118185] xmms            S    0  2849   2329 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.118992] kworker/0:6     I    0  2346      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.119203] kworker/0:14    I    0  2362      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.119424] fish            S    0  2414   1422 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.120179] kworker/u16:1   I    0  2455      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.120408] kworker/0:23    I    0  2520      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.120617] kworker/0:25    I    0  2540      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.120821] kworker/u16:0   I    0  2641      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.121027] kworker/2:1     I    0  2763      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.121231] kworker/0:0     I    0  2782      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.121451] kworker/0:1     I    0  2850      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.121657] kworker/0:2     I    0  2866      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.121861] kworker/0:3     I    0  2867      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.122066] kworker/2:0     I    0  2877      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.122273] kworker/0:5     I    0  2890      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.122495] kworker/0:7     I    0  2908      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.122705] kworker/0:8     I    0  2914      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.122910] kworker/0:9     I    0  2944      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.123115] kworker/0:10    I    0  2945      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.123335] kworker/0:13    I    0  2978      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.123543] kworker/0:15    I    0  2980      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.123749] xterm           S    0  2981   1126 0x00000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.124568] kworker/0:16    I    0  2984      2 0x80000000
> Jan 10 17:56:20 darkbook kernel: [ 2819.124775] kworker/0:17    I    0  2987      2 0x80000000
> Jan 10 17:56:21 darkbook kernel: [ 2819.173457] Showing busy workqueues and worker pools:
> Jan 10 17:56:21 darkbook kernel: [ 2819.173480] workqueue events_freezable: flags=0x4
> Jan 10 17:56:21 darkbook kernel: [ 2819.173502]   pwq 4: cpus=2 node=0 flags=0x0 nice=0 active=1/256
> Jan 10 17:56:21 darkbook kernel: [ 2819.173540]     in-flight: 1635:mmc_rescan
> Jan 10 17:56:21 darkbook kernel: [ 2819.173599] pool 4: cpus=2 node=0 flags=0x0 nice=0 hung=0s workers=3 idle: 2877 2763
> Jan 10 17:56:21 darkbook kernel: [ 2820.056697] sysrq: SysRq : Show clockevent devices & pending hrtimers (no others)
> Jan 10 17:56:23 darkbook kernel: [ 2821.458675] sysrq: SysRq : Show Regs
> Jan 10 17:56:23 darkbook kernel: [ 2821.459453] 
> Jan 10 17:56:23 darkbook kernel: [ 2821.459464] CPU#0: ctrl:       000000000000000f
> Jan 10 17:56:23 darkbook kernel: [ 2821.459482] CPU#0: status:     8000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459500] CPU#0: overflow:   0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459518] CPU#0: fixed:      0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459537] CPU#0: pebs:       0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459555] CPU#0: debugctl:   0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459573] CPU#0: active:     0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459592] CPU#0:   gen-PMC0 ctrl:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459611] CPU#0:   gen-PMC0 count: 0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459630] CPU#0:   gen-PMC0 left:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459650] CPU#0:   gen-PMC1 ctrl:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459670] CPU#0:   gen-PMC1 count: 0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459689] CPU#0:   gen-PMC1 left:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459709] CPU#0:   gen-PMC2 ctrl:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459728] CPU#0:   gen-PMC2 count: 0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459748] CPU#0:   gen-PMC2 left:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459767] CPU#0:   gen-PMC3 ctrl:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459787] CPU#0:   gen-PMC3 count: 000000000000ffff
> Jan 10 17:56:23 darkbook kernel: [ 2821.459806] CPU#0:   gen-PMC3 left:  0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459826] CPU#0: fixed-PMC0 count: 0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459846] CPU#0: fixed-PMC1 count: 0000000000000000
> Jan 10 17:56:23 darkbook kernel: [ 2821.459866] CPU#0: fixed-PMC2 count: 0000000000000000
> Jan 10 17:56:24 darkbook kernel: [ 2822.972704] sysrq: SysRq : Show Memory
> Jan 10 17:56:24 darkbook kernel: [ 2822.973707] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
> Jan 10 17:56:28 darkbook kernel: [ 2827.075135] sysrq: SysRq : Emergency Sync
> Jan 10 17:56:31 darkbook exiting on signal 15
> ===
> 
> The last one is me issuing a terminate-all-tasks so I can safely reboot.
> 
> This is a regular build with many tracing/tracers options plus some
> debugging info.  It is available at <http://rnsanchez.wait4.org/config-4.14>,
> if you need it.
> 
> Let me know if you need more info.
> 
> Cheers,
> 

Some context of this problem :

commit 29869d66870a715177bfb505f66a7e0e8bcc89c3
Author: Eric Dumazet <[email-masked]>
Date:   Tue Feb 21 06:21:47 2017 -0800

    tcp: Revert "tcp: tcp_probe: use spin_lock_bh()"
    
    This reverts commit e70ac171658679ecf6bea4bbd9e9325cd6079d2b.
    
    jtcp_rcv_established() is in fact called with hard irq being disabled.
    
    Initial bug report from Ricardo Nabinger Sanchez [1] still needs
    to be investigated, but does not look like a TCP bug.
    
    [1] https://www.spinics.net/lists/netdev/msg420960.html
    
    Signed-off-by: Eric Dumazet <[email-masked]>
    Reported-by: kernel test robot <[email-masked]>
    Cc: Ricardo Nabinger Sanchez <[email-masked]>
    Signed-off-by: David S. Miller <[email-masked]>

commit e70ac171658679ecf6bea4bbd9e9325cd6079d2b
Author: Eric Dumazet <[email-masked]>
Date:   Tue Feb 14 17:11:14 2017 -0800

    tcp: tcp_probe: use spin_lock_bh()
    
    tcp_rcv_established() can now run in process context.
    
    We need to disable BH while acquiring tcp probe spinlock,
    or risk a deadlock.
    
    Fixes: 5413d1babe8f ("net: do not block BH while processing socket backlog")
    Signed-off-by: Eric Dumazet <[email-masked]>
    Reported-by: Ricardo Nabinger Sanchez <[email-masked]>
    Signed-off-by: David S. Miller <[email-masked]>