Re: 2.6.18-rt1

Lee Revell
2006-09-30T18:06:06Z

On Wed, 2006-09-20 at 16:19 +0200, Ingo Molnar wrote:
> I'm pleased to announce the 2.6.18-rt1 tree, which can be downloaded
> from the usual place:
>
> http://redhat.com/~mingo/realtime-preempt/

I got this Oops with -rt3, looks RCU related. Apologies in advance if
it's already known.

Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP:
[<ffffffff802aafa7>] __rcu_read_unlock+0x2e/0x82
PGD 46a3067 PUD 4e27067 PMD 0
Oops: 0002 [1] PREEMPT SMP
CPU 1
Modules linked in: rfcomm hidp l2cap bluetooth nfsd exportfs lockd nfs_acl sunrpc powernow_k8 cpufreq_userspace cpufreq_stats freq_table cpufreq_powersave cpufreq_ondemand cpufreq_conservative video button battery container ac asus_acpi dm_mod md_mod sr_mod sbp2 lp psmouse serio_raw sg evdev floppy parport_pc parport pcspkr i2c_nforce2 i2c_core shpchp pci_hotplug ext3 jbd mbcache ohci_hcd ehci_hcd ohci1394 ieee1394 forcedeth ide_generic ide_cd cdrom sd_mod sata_nv libata scsi_mod generic amd74xx ide_core thermal processor fan
Pid: 21372, comm: fixdep Not tainted 2.6.18-rt3-smp-noipv6 #1
RIP: 0010:[<ffffffff802aafa7>] [<ffffffff802aafa7>] __rcu_read_unlock+0x2e/0x82
RSP: 0018:ffff8100045dbbf0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff810015a63070 RCX: 0000000000000246
RDX: 0000000000000000 RSI: ffff8100188bf007 RDI: ffff810015a63078
RBP: ffff810015a63070 R08: 0000000000000000 R09: ffff81001212d6c0
R10: ffff81001b9c0d48 R11: ffffffff8022ae94 R12: ffff810015a63078
R13: ffff8100119da4b0 R14: ffff8100045dbca8 R15: 0000000071bf92cd
FS: 00002b7fb742d6d0(0000) GS:ffff81001b9178c0(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 00000000194c3000 CR4: 00000000000006e0
Process fixdep (pid: 21372, threadinfo ffff8100045da000, task ffff81001622d800)
Stack: ffffffff80208db8 0000000100000105 0000000700000001 ffff8100188bf000
00000000000041ed ffff8100045dbea8 ffff8100119f5180 ffff810001232480
ffff8100045dbea8 ffff8100045dbca8 ffffffff8020c353 ffff81001b9c0d00
Call Trace:
[<ffffffff80208db8>] __d_lookup+0x10b/0x11d
[<ffffffff8020c353>] do_lookup+0x2a/0x173
[<ffffffff80209179>] __link_path_walk+0x3af/0xf5c
[<ffffffff8020c537>] file_read_actor+0x0/0xce
[<ffffffff80299575>] _atomic_dec_and_spin_lock+0x2b/0x33
[<ffffffff8020dc2c>] link_path_walk+0x5c/0xe5
[<ffffffff8029955e>] _atomic_dec_and_spin_lock+0x14/0x33
[<ffffffff80213fe4>] get_unused_fd+0xf9/0x107
[<ffffffff802117be>] filemap_nopage+0x1cb/0x39b
[<ffffffff8020c201>] do_path_lookup+0x26c/0x290
[<ffffffff8029a09b>] __rt_rwlock_init+0x9/0x12
[<ffffffff80221a87>] __path_lookup_intent_open+0x56/0x97
[<ffffffff8021909c>] open_namei+0x6d/0x6a4
[<ffffffff8021ca81>] free_pgtables+0xe6/0x172
[<ffffffff802bbada>] __cache_free+0x51/0x1f2
[<ffffffff80225776>] do_filp_open+0x1c/0x3d
[<ffffffff8029955e>] _atomic_dec_and_spin_lock+0x14/0x33
[<ffffffff80213fe4>] get_unused_fd+0xf9/0x107
[<ffffffff80217e96>] do_sys_open+0x44/0xc5
[<ffffffff8025b1ce>] system_call+0x7e/0x83

Code: f0 ff 08 65 48 8b 04 25 00 00 00 00 48 c7 80 a8 00 00 00 00
RIP [<ffffffff802aafa7>] __rcu_read_unlock+0x2e/0x82
RSP <ffff8100045dbbf0>
CR2: 0000000000000000