Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0

[Florian Schmidt]

On Mon, 25 Oct 2004 15:26:05 +0200
Ingo Molnar <mingo@xxxxxxx> wrote:

> does the patch below fix this?

looks like it. they didn't show on first boot of the new kernel with patch
applied. 

Btw: i still experience some "pauses". They are different now though. It
seems i can trigger them by reloading a page in mozilla (not always). This
BUG definetly looks related. Dunno, when exactly it happened (related to
what i did at that moment), but it's the only one in dmesg output on this
bootup. Each of the pauses is accompanied by a high cpu usage of ksoftirqd.
I cannot retrigger the BUG though.

mozilla-bin/763: BUG in futex_wait at kernel/futex.c:542
 [<c0132962>] futex_wait+0x192/0x1a0 (12)
 [<c0131c55>] sub_preempt_count+0x65/0xd0 (64)
 [<c01ef17b>] __up_write+0x13b/0x320 (8)
 [<c0131788>] check_preempt_timing+0x58/0x290 (8)
 [<c0131c55>] sub_preempt_count+0x65/0xd0 (4)
 [<c01ef17b>] __up_write+0x13b/0x320 (4)
 [<c02b94d3>] down_read+0xd3/0x2b0 (8)
 [<c0131c55>] sub_preempt_count+0x65/0xd0 (4)
 [<c01eef11>] up_read+0x111/0x240 (8)
 [<c0131788>] check_preempt_timing+0x58/0x290 (8)
 [<c0131c55>] sub_preempt_count+0x65/0xd0 (4)
 [<c01eef11>] up_read+0x111/0x240 (4)
 [<c0115f60>] default_wake_function+0x0/0x20 (104)
 [<c0115f60>] default_wake_function+0x0/0x20 (32)
 [<c0132c17>] do_futex+0x47/0xa0 (40)
 [<c0132d60>] sys_futex+0xf0/0x100 (40)
 [<c010617b>] syscall_call+0x7/0xb (68)
preempt count: 00000001
. 1-level deep critical section nesting:
.. entry 1: print_traces+0x17/0x90 [<c0131fc7>] / (dump_stack+0x23/0x30 [<c0106733>])

Here's the syslog entry:

Oct 25 15:56:31 mango kernel: mozilla-bin/763: BUG in futex_wait at kernel/futex.c:542
Oct 25 15:56:31 mango kernel:  [futex_requeue+162/608] futex_wait+0x192/0x1a0 (12)
Oct 25 15:56:31 mango kernel:  [print_name_offset+149/160] sub_preempt_count+0x65/0xd0 (64)
Oct 25 15:56:31 mango kernel:  [zlib_inflateReset+43/128] __up_write+0x13b/0x320 (8)
Oct 25 15:56:31 mango kernel:  [kfifo_alloc+216/240] check_preempt_timing+0x58/0x290 (8)
Oct 25 15:56:31 mango kernel:  [print_name_offset+149/160] sub_preempt_count+0x65/0xd0 (4)
Oct 25 15:56:31 mango kernel:  [zlib_inflateReset+43/128] __up_write+0x13b/0x320 (4)
Oct 25 15:56:31 mango kernel:  [__func__.0+318/987] down_read+0xd3/0x2b0 (8)
Oct 25 15:56:31 mango kernel:  [print_name_offset+149/160] sub_preempt_count+0x65/0xd0 (4)
Oct 25 15:56:31 mango kernel:  [zlib_inflate_fast+465/1024] up_read+0x111/0x240 (8)
Oct 25 15:56:31 mango kernel:  [kfifo_alloc+216/240] check_preempt_timing+0x58/0x290 (8)
Oct 25 15:56:31 mango kernel:  [print_name_offset+149/160] sub_preempt_count+0x65/0xd0 (4)
Oct 25 15:56:31 mango kernel:  [zlib_inflate_fast+465/1024] up_read+0x111/0x240 (4)
Oct 25 15:56:31 mango kernel:  [wake_up_process+32/48] default_wake_function+0x0/0x20 (104)
Oct 25 15:56:31 mango kernel:  [wake_up_process+32/48] default_wake_function+0x0/0x20 (32)
Oct 25 15:56:31 mango kernel:  [unqueue_me+103/256] do_futex+0x47/0xa0 (40)
Oct 25 15:56:31 mango kernel:  [futex_wait+176/400] sys_futex+0xf0/0x100 (40)
Oct 25 15:56:31 mango kernel:  [irq_entries_start+107/128] syscall_call+0x7/0xb (68)
Oct 25 15:56:31 mango kernel: preempt count: 00000001
Oct 25 15:56:31 mango kernel: . 1-level deep critical section nesting:
Oct 25 15:56:31 mango kernel: .. entry 1: print_traces+0x17/0x90 [update_max_trace+23/160] / (dump_stack+0x23/0x30 [show_registers+131/464])
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