On Fri, 23 Jul 2010 14:15:51 +0200 (CEST) "Rafael J. Wysocki" <rjw@xxxxxxx> wrote: > This message has been generated automatically as a part of a report > of regressions introduced between 2.6.33 and 2.6.34. > > The following bug entry is on the current list of known regressions > introduced between 2.6.33 and 2.6.34. Please verify if it still should > be listed and let the tracking team know (either way). > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=16206 > Subject : PROBLEM: PPP and other serial port related application hangs in kernel space > Submitter : Ales Teska <ales.teska@xxxxxxxxx> > Date : 2010-06-09 20:46 (45 days old) > Message-ID : <900E3B14-5B92-4A37-9581-049DB40F4D1C@xxxxxxxxx> > References : http://marc.info/?l=linux-kernel&m=127611640301071&w=2 > I think this is some kind of race in the ldisc handling code. 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() [ 1673.689168] 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 With softlockup detection enabled, there is also this trace: [ 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 [ 841.151250] 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 I put the full traces into the bug report. -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
