Subject : PROBLEM: PPP and other serial port related application hangs in kernel space Submitter : Ales Teska <ales.teska@gmail.com> Date : 2010-06-09 20:46 Message-ID : 900E3B14-5B92-4A37-9581-049DB40F4D1C@gmail.com References : http://marc.info/?l=linux-kernel&m=127611640301071&w=2 This entry is being used for tracking a regression from 2.6.33. Please don't close it until the problem is fixed in the mainline.
This patch went in 2.6.34: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff_plain;h=638b9648ab51c9c549ff5735d3de519ef6199df3 "tty: Fix the ldisc hangup race"
Warning message from the original report: Line 1278 is: WARN_ON(!test_bit(TTY_LDISC, &tty->flags)); [ 1673.660876] ------------[ cut here ]------------ [ 1673.661471] WARNING: at drivers/char/tty_io.c:1278 tty_open+0x213/0x451() [ 1673.662358] Modules linked in: ppp_deflate zlib_deflate bsd_comp ppp_async crc_ccitt ppp_generic slhc ipv6 nvram msr cpuid ledtrig_timer ledtrig_heartbeat ledtrig_default_on geodewdt lm90 hwmon scx200_acb option usbserial ehci_hcd ohci_hcd via_rhine usbcore leds_alix2 mii [ 1673.689168] Pid: 1275, comm: ufoprobe_client Not tainted 2.6.34-486-exiprobes #1 [ 1673.690452] Call Trace: [ 1673.690947] [<c10e93af>] ? tty_open+0x213/0x451 [ 1673.691926] [<c1018f51>] warn_slowpath_common+0x45/0x5c [ 1673.693006] [<c1018f75>] warn_slowpath_null+0xd/0x10 [ 1673.694293] [<c10e93af>] tty_open+0x213/0x451 [ 1673.694755] [<c1068105>] chrdev_open+0xe3/0x126 [ 1673.695733] [<c10648e5>] __dentry_open+0x123/0x1f7 [ 1673.697472] [<c10655f8>] nameidata_to_filp+0x29/0x3d [ 1673.697726] [<c1068022>] ? chrdev_open+0x0/0x126 [ 1673.698957] [<c106d961>] do_last+0x361/0x474 [ 1673.700138] [<c1066861>] ? percpu_counter_add+0x23/0x2f [ 1673.701189] [<c106ed97>] do_filp_open+0x165/0x3b5 [ 1673.701700] [<c10212e8>] ? update_process_times+0x3a/0x3e [ 1673.703295] [<c1075c1b>] ? spin_unlock+0x17/0x22 [ 1673.704537] [<c10646ac>] do_sys_open+0x4a/0xec [ 1673.705244] [<c1064790>] sys_open+0x1e/0x26 [ 1673.706190] [<c118c835>] syscall_call+0x7/0xb [ 1673.706644] [<c1180000>] ? xfrm_add_pol_expire+0x7a/0x166 [ 1673.708205] ---[ end trace 69d4cf5dc236c7af ]---
[ 841.121579] INFO: task pppd:1390 blocked for more than 120 seconds. [ 841.122613] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 841.123578] pppd D cec53ea4 0 1390 1139 0x00000000 [ 841.126502] cec53ebc 00000046 c1037b30 cec53ea4 c1198bf6 cec29070 cec291f8 cfdbc520 [ 841.134781] c10f7049 cec53ebc 00000000 cec51800 cec53ec4 cec53ee4 c10f79fb 00000000 [ 841.143007] cec29070 c102b471 c13dc904 c13dc904 d0c35211 cefc6aa0 cec51800 cec53f1c [ 841.151250] Call Trace: [ 841.151815] [<c1037b30>] ? trace_hardirqs_on+0xb/0xd [ 841.152755] [<c1198bf6>] ? _raw_spin_unlock_irqrestore+0x53/0x60 [ 841.153657] [<c10f7049>] ? spin_unlock_irqrestore+0x8/0xa [ 841.154601] [<c10f79fb>] tty_ldisc_ref_wait+0x5d/0x75 [ 841.155265] [<c102b471>] ? autoremove_wake_function+0x0/0x33 [ 841.156456] [<d0c35211>] ? serial_ioctl+0x0/0x68 [usbserial] [ 841.157913] [<c10f3c54>] tty_ioctl+0x6d1/0x731 [ 841.158834] [<c102fa77>] ? sched_clock_cpu+0xac/0xbc [ 841.159658] [<c10f3583>] ? tty_ioctl+0x0/0x731 [ 841.160922] [<c1077e6c>] vfs_ioctl+0x22/0x86 [ 841.161836] [<c10783ba>] do_vfs_ioctl+0x45a/0x4a5 [ 841.162746] [<c1036a5e>] ? put_lock_stats+0xd/0x21 [ 841.163699] [<c1036ac6>] ? lock_release_holdtime+0x54/0x5a [ 841.164530] [<c100fd87>] ? do_page_fault+0x27c/0x285 [ 841.165898] [<c102e978>] ? up_read+0x16/0x28 [ 841.166820] [<c1078431>] sys_ioctl+0x2c/0x45 [ 841.167452] [<c1198e65>] syscall_call+0x7/0xb [ 841.168403] no locks held by pppd/1390.
Any update on this bug? I am encountering it on 2.6.32.