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Subject: Re: [patch] preempt-timing-on-2.6.8-rc2-O2
From: Lee Revell <rlrevell@joe-job.com>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel <linux-kernel@vger.kernel.org>
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Date: Sun, 08 Aug 2004 00:21:16 -0400
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On Sat, 2004-08-07 at 22:48, William Lee Irwin III wrote:

> It's probably actually a false positive. What I was explaining was why,
> if it were in fact a non-preemptible critical section, it wouldn't cause
> xruns.
> 

These two seem to be real.  It looks like get_user_pages is still
problematic in 2.6.8-rc2.

(jackd/6219): 10943us non-preemptible critical section violated 1000 us preempt threshold starting at kmap_atomic+0x10/0x60 and ending at kunmap_atomic+0x8/0x20
 [<c0106717>] dump_stack+0x17/0x20
 [<c0113eec>] dec_preempt_count+0x3c/0x50
 [<c0111ce8>] kunmap_atomic+0x8/0x20
 [<c013e2cb>] do_anonymous_page+0x8b/0x190
 [<c013e41e>] do_no_page+0x4e/0x310
 [<c013e8a1>] handle_mm_fault+0xc1/0x170
 [<c013d280>] get_user_pages+0x110/0x380
 [<c013e9f8>] make_pages_present+0x68/0x90
 [<c0140196>] do_mmap_pgoff+0x3e6/0x620
 [<c010b656>] sys_mmap2+0x76/0xb0
 [<c01060b7>] syscall_call+0x7/0xb
ALSA /home/rlrevell/cvs/alsa/alsa-driver/alsa-kernel/core/pcm_lib.c:139: XRUN: pcmC0D2c
 [<c0106717>] dump_stack+0x17/0x20
 [<de93d64b>] snd_pcm_period_elapsed+0x27b/0x3e0 [snd_pcm]
 [<de9791d1>] snd_emu10k1_interrupt+0xd1/0x3c0 [snd_emu10k1]
 [<c011a7d3>] generic_handle_IRQ_event+0x33/0x60
 [<c01079c2>] do_IRQ+0xb2/0x180
 [<c01062d8>] common_interrupt+0x18/0x20
 [<c0113e18>] __touch_preempt_timing+0x8/0x20
 [<c0113ea2>] inc_preempt_count+0x32/0x40
 [<c014cb8e>] fget+0x1e/0x60
 [<c015ecdd>] do_pollfd+0x2d/0xa0
 [<c015edaf>] do_poll+0x5f/0xc0
 [<c015ef41>] sys_poll+0x131/0x220
 [<c01060b7>] syscall_call+0x7/0xb
(gnome-terminal/914): 10738us non-preemptible critical section violated 1000 us preempt threshold starting at fget+0x1e/0x60 and ending at fget+0x3d/0x60
 [<c0106717>] dump_stack+0x17/0x20
 [<c0113eec>] dec_preempt_count+0x3c/0x50
 [<c014cbad>] fget+0x3d/0x60
 [<c015ecdd>] do_pollfd+0x2d/0xa0
 [<c015edaf>] do_poll+0x5f/0xc0
 [<c015ef41>] sys_poll+0x131/0x220
 [<c01060b7>] syscall_call+0x7/0xb

Lee