[BUG] using smp_processor_id() in preemptible

From: Luis Henriques
Date: Sat Nov 15 2008 - 18:31:22 EST


Hi Ingo,

while running latencytop, got the following:

...
[ 775.663239] BUG: using smp_processor_id() in preemptible [00000000] code: latencytop/6585
[ 775.663303] caller is native_sched_clock+0x3a/0x80
[ 775.663314] Pid: 6585, comm: latencytop Tainted: G W 2.6.28-rc4-00355-g9c7c354 #1
[ 775.663322] Call Trace:
[ 775.663343] [<ffffffff803a94e4>] debug_smp_processor_id+0xe4/0xf0
[ 775.663356] [<ffffffff80213f7a>] native_sched_clock+0x3a/0x80
[ 775.663368] [<ffffffff80213e19>] sched_clock+0x9/0x10
[ 775.663381] [<ffffffff8024550d>] proc_sched_show_task+0x8bd/0x10e0
[ 775.663395] [<ffffffff8034466e>] sched_show+0x3e/0x80
[ 775.663408] [<ffffffff8031039b>] seq_read+0xdb/0x350
[ 775.663421] [<ffffffff80368776>] ? security_file_permission+0x16/0x20
[ 775.663435] [<ffffffff802f4198>] vfs_read+0xc8/0x170
[ 775.663447] [<ffffffff802f4335>] sys_read+0x55/0x90
[ 775.663460] [<ffffffff8020c67a>] system_call_fastpath+0x16/0x1b
...

I am running 2.6.28-rc4-00355-g9c7c354 and, after taking a look at the code, it
looks like the problem is in commit 7cbaef9c83e58bbd4bdd534b09052b6c5ec457d5,
where native_sched_clock is modified to use __cycles_2_ns instead of
cycles_2_ns.

--
Luis Henriques
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