* Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote: > On Wed, 2009-01-14 at 10:53 -0800, Andrew Morton wrote: > > On Wed, 14 Jan 2009 19:33:19 +0100 Ingo Molnar <mingo@xxxxxxx> wrote: > > > > > Please pull the adaptive-mutexes-for-linus git tree > > > > <fear> > > > > - It seems a major shortcoming that the feature is disabled if > > CONFIG_DEBUG_MUTEXES=y. It means that lots of people won't test it. > > Yes, that's a bit unfortunate, a simple patch to enable that is: > > I must admit I'm a bit stumped on why that debug check triggers, I > couldn't reproduce today, but Ingo ran into it quite quickly :/ Yes, the debug patch caused this false positive warning on one of my test-systems: Built 1 zonelists in Zone order, mobility grouping on. Total pages: 255762 ------------[ cut here ]------------ WARNING: at kernel/mutex-debug.c:77 debug_mutex_unlock+0x94/0xde() Hardware name: Modules linked in: Pid: 0, comm: swapper Not tainted 2.6.29-rc1-tip-00983-ge1af3bd-dirty #1 Call Trace: [<ffffffff8024f2f7>] warn_slowpath+0xd8/0xf7 [<ffffffff8024f5ec>] ? wake_up_klogd+0x9/0x2f [<ffffffff80270fd1>] ? graph_lock+0x27/0x66 [<ffffffff80275329>] ? validate_chain+0xd4d/0xd9f [<ffffffff802714c4>] ? save_trace+0x3f/0xb2 [<ffffffff80275b4f>] ? __lock_acquire+0x7d4/0x832 [<ffffffff80275c5f>] ? lock_acquire+0xb2/0xc2 [<ffffffff8025091c>] ? cpu_maps_update_begin+0x17/0x19 [<ffffffff80271d21>] ? trace_hardirqs_off+0xd/0xf [<ffffffff80270a8e>] debug_mutex_unlock+0x94/0xde [<ffffffff80906d71>] __mutex_unlock_slowpath+0xdd/0x152 [<ffffffff80906df4>] mutex_unlock+0xe/0x10 [<ffffffff80250955>] cpu_maps_update_done+0x15/0x17 [<ffffffff808ce8b5>] register_cpu_notifier+0x2c/0x32 [<ffffffff80d7683e>] page_alloc_init+0x10/0x12 [<ffffffff80d5ac45>] start_kernel+0x1ba/0x422 [<ffffffff80d5a140>] ? early_idt_handler+0x0/0x73 [<ffffffff80d5a2c3>] x86_64_start_reservations+0xae/0xb2 [<ffffffff80d5a421>] x86_64_start_kernel+0x137/0x146 ---[ end trace a7919e7f17c0a725 ]--- Kernel command line: root=/dev/sda1 earlyprintk=serial,ttyS0,115200 console=ttyS0,115200 console=tty 5 profile=0 debug initcall_debug apic=debug apic=verbose ignore_loglevel sysrq_always_enabled pci=nomsi kernel profiling enabled (shift: 0) debug: sysrq always enabled. Initializing CPU#0 So we left that change out from this pull request. It's not a big deal i think - mutex debugging always had a different fast-path from no-debug mutexes anyway (or a lack of fast-path to begin with). So the performance characteristics were always subtly different. Now they might be more different - but we'll fix that too. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
