2.6.24-rc7 to 2.6.24-rc8 possible regression

From: Denys Fedoryshchenko
Date: Mon Jan 21 2008 - 11:06:50 EST


After running screen found in dmesg. It was not happening before.

[625138.248257]
[625138.248260] =============================================
[625138.248542] [ INFO: possible recursive locking detected ]
[625138.248686] 2.6.24-rc8-devel #2
[625138.248821] ---------------------------------------------
[625138.248963] screen/18164 is trying to acquire lock:
[625138.249101] (&q->lock){++..}, at: [<c01175ff>] __wake_up+0x15/0x42
[625138.249454]
[625138.249456] but task is already holding lock:
[625138.249724] (&q->lock){++..}, at: [<c01175ff>] __wake_up+0x15/0x42
[625138.250073]
[625138.250075] other info that might help us debug this:
[625138.250343] 2 locks held by screen/18164:
[625138.250477] #0: (&tty->atomic_read_lock){--..}, at: [<c0231a6c>]
read_chan+0x18f/0x50b
[625138.250960] #1: (&q->lock){++..}, at: [<c01175ff>] __wake_up+0x15/0x42
[625138.251356]
[625138.251357] stack backtrace:
[625138.251623] Pid: 18164, comm: screen Not tainted 2.6.24-rc8-devel #2
[625138.251764] [<c0105e84>] show_trace_log_lvl+0x1a/0x2f
[625138.251959] [<c010682c>] show_trace+0x12/0x14
[625138.252150] [<c0107123>] dump_stack+0x6c/0x72
[625138.252338] [<c01384c0>] __lock_acquire+0x172/0xb8c
[625138.252533] [<c01392a7>] lock_acquire+0x5f/0x78
[625138.252725] [<c032afa7>] _spin_lock_irqsave+0x34/0x44
[625138.252920] [<c01175ff>] __wake_up+0x15/0x42
[625138.253108] [<c0186a16>] ep_poll_safewake+0x8e/0xbf
[625138.253300] [<c01876df>] ep_poll_callback+0x9f/0xac
[625138.253491] [<c0115d36>] __wake_up_common+0x32/0x5c
[625138.253688] [<c011761b>] __wake_up+0x31/0x42
[625138.253878] [<c022c803>] tty_wakeup+0x4f/0x54
[625138.254070] [<c0232c7c>] pty_unthrottle+0x15/0x21
[625138.254258] [<c022ffe3>] check_unthrottle+0x2e/0x30
[625138.254445] [<c0231cf4>] read_chan+0x417/0x50b
[625138.254633] [<c022ec67>] tty_read+0x66/0xac
[625138.254819] [<c01628dc>] vfs_read+0x8e/0x117
[625138.255004] [<c0162d10>] sys_read+0x3d/0x61
[625138.255190] [<c0104dee>] sysenter_past_esp+0x5f/0xa5
[625138.255376] =======================



--
Denys Fedoryshchenko
Technical Manager
Virtual ISP S.A.L.

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