2009/1/11 Ingo Molnar <mingo@xxxxxxx>: > > * Ingo Molnar <mingo@xxxxxxx> wrote: > >> * Dmitry Adamushko <dmitry.adamushko@xxxxxxxxx> wrote: >> >> > Hi, >> > >> > >> > This is in response to the following bug report: >> > >> > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12100 >> > Subject : resume (S2R) broken by Intel microcode module, on A110L >> > Submitter : Andreas Mohr <andi@xxxxxxxx> >> > Date : 2008-11-25 08:48 (19 days old) >> > Handled-By : Dmitry Adamushko <dmitry.adamushko@xxxxxxxxx> >> >> applied to tip/x86/microcode, thanks Dmitry! >> >> The fix looks right but somewhat intrusive in scope, so i'm a bit >> reluctant to push it towards .28 straight away - without having feedback >> in the bugzilla. If feedback is positive (the bug reported there goes >> away completely) we can cherry-pick it over into x86/urgent, ok? And in >> any case i've marked it as a -stable backport for .28.1. > > hm, -tip testing just found this microcode locking lockdep splat: > > [ 48.004158] SMP alternatives: switching to UP code > [ 48.342853] CPU0 attaching NULL sched-domain. > [ 48.344288] CPU1 attaching NULL sched-domain. > [ 48.354696] CPU0 attaching NULL sched-domain. > [ 48.361215] device: 'cpu1': device_unregister > [ 48.364231] device: 'cpu1': device_create_release > [ 48.368138] > [ 48.368139] ======================================================= > [ 48.372039] [ INFO: possible circular locking dependency detected ] > [ 48.372039] 2.6.29-rc1-tip-00901-g9699183-dirty #15577 > [ 48.372039] ------------------------------------------------------- > [ 48.372039] S99local/3496 is trying to acquire lock: > [ 48.372039] (microcode_mutex){--..}, at: [<c0118489>] microcode_fini_cpu+0x17/0x2b > [ 48.372039] > [ 48.372039] but task is already holding lock: > [ 48.372039] (&cpu_hotplug.lock){--..}, at: [<c012f508>] cpu_hotplug_begin+0x1f/0x47 > [ 48.372039] > [ 48.372039] which lock already depends on the new lock. > [ 48.372039] > [ 48.372039] > [ 48.372039] the existing dependency chain (in reverse order) is: > [ 48.372039] > [ 48.372039] -> #1 (&cpu_hotplug.lock){--..}: > [ 48.372039] [<c014d3f1>] validate_chain+0x8e9/0xb94 > [ 48.372039] [<c014dd03>] __lock_acquire+0x667/0x6e1 > [ 48.372039] [<c014ddda>] lock_acquire+0x5d/0x7a > [ 48.372039] [<c0a6fac3>] mutex_lock_nested+0xdc/0x170 > [ 48.372039] [<c012f552>] get_online_cpus+0x22/0x34 > [ 48.372039] [<c013ce08>] work_on_cpu+0x50/0x8a > [ 48.372039] [<c0118465>] microcode_init_cpu+0x25/0x32 > [ 48.372039] [<c0118699>] mc_sysdev_add+0x91/0x9b > [ 48.372039] [<c04cbd09>] sysdev_driver_register+0x9b/0xea I'll check more carefully... At the first glance, the presence of work_on_cpu() looks strange. My first idea was that it's used somewhere by request_firmware() but even assuming some functions might have been inlined (and a call via a function pointer is not shown either), I don't immediately see how we might end up with microcode_init_cpu() -> ... -> work_on_cpu(). I've locked up all the use cases of work_on_cpu() in the current -tip (about 20), and none of them seem to explain its appearance in the trace. weird... > > Ingo > -- Best regards, Dmitry Adamushko -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
