Messages in this thread | | | Date | Thu, 27 Mar 2008 00:23:04 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [patch 2/5] infrastructure to debug (dynamic) objects |
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On Tue, 25 Mar 2008, Thomas Gleixner wrote: > On Mon, 24 Mar 2008, Andrew Morton wrote: > > On Fri, 21 Mar 2008 20:26:18 -0000 > > Thomas Gleixner <tglx@linutronix.de> wrote: > > > > > The debugobjects core code keeps track of operations on static and > > > dynamic objects by inserting them into a hashed list and sanity > > > checking them on object operations and provides additional checks > > > whenever kernel memory is freed. > > > > Prime candidates for conversion to this interface are locks: spinlocks, > > rwlocks, mutexes, etc. > > > > a) it'd be interesting to get that done, as a proof-of-usefulness thing. > > /me looks for volunteers :)
I had a look into that and it's not a friday afternoon project as it needs some major distangling of lockdep, which seems to be on Peter's todo list for quite a while.
vs. the proof-of-usefulness I just want to point out that having an infrastructure which allows us to retrieve valuable debug information with an exact pointer to the offending code from a live system is useful by definition and it has proven it already in several cases.
I was able to fix two of those problems (use after free) myself, but I'm unable to get this one resolved w/o twisting my brain:
http://bugzilla.kernel.org/show_bug.cgi?id=10068
But .... having such precise info:
ODEBUG: init active object: db112e94 timer_list WARNING: at lib/debugobjects.c:63 debug_print_object() Pid: 2023, comm: softmac Not tainted 2.6.24.2 #10 [<c01c5181>] debug_object_op+0x89/0xe0 [<c0120168>] init_timer+0x18/0x40 [<e098f813>] ieee80211softmac_auth_req+0x6b/0x9c [ieee80211softmac] [<e0991543>] ieee80211softmac_assoc_work+0x292/0x392 [ieee80211softmac] [<e0991643>] ieee80211softmac_assoc_notify_scan+0x0/0x10 [ieee80211softmac] [<e0991ab6>] ieee80211softmac_notify_callback+0x40/0x48 [ieee80211softmac] [<e0991a76>] ieee80211softmac_notify_callback+0x0/0x48 [ieee80211softmac] [<e0991978>] ieee80211softmac_call_events_locked+0xdc/0xee [ieee80211softmac] [<e0991643>] ieee80211softmac_assoc_notify_scan+0x0/0x10 [ieee80211softmac] [<e0991a76>] ieee80211softmac_notify_callback+0x0/0x48 [ieee80211softmac] [<c01250bf>] run_workqueue+0x6b/0xdf [<c0335f0f>] schedule+0x1f0/0x20a [<c01256b2>] worker_thread+0x0/0xc2 [<c0125766>] worker_thread+0xb4/0xc2 [<c0127baa>] autoremove_wake_function+0x0/0x33 [<c01256b2>] worker_thread+0x0/0xc2 [<c0127a4a>] kthread+0x36/0x5c [<c0127a14>] kthread+0x0/0x5c [<c0104757>] kernel_thread_helper+0x7/0x10
instead of:
kernel BUG at kernel/timer.c: 607! Invalid opcode: 0000 [#1] Modules linked in: cpufreq_stats nls_cp437 sbp2 scsi_mod loop zd1211rw ieee80211softmac parport_pc parport ohci1394 snd_intel8x0 ieee1394 sis900 ehci_hcd ide_cd cdrom fan asus_acpi backlight battery ac
Pid 3239, comm: firefox-bin Not tainted (2.6.24.2 #1) EIP:0060 :[<c011e54b>] EFLAGS:00210007 CPU:0 EIP is at cascade+0x3b/0x57 EAX:0 EBX:0 ECX:5 EDX:d9eb3ca4 ESI:5 EDI:c0485640 EBP:d9ecdf30 ESP:d9ecdf30 DS:007b ES:007b FS:0000 GS:0033 SS:0068
...
Call trace
[<c011e6ad>] run_timer_softirq+0x55/0x141 [<c012b8e3>] tick_handle_periodic+0xf/0x54 [<c011bdcc>] __do_softirq+0x35/0x75 [<c011be2e>] do_softirq+022/0x26 [<c01055b0>] do_IRQ+0x58/0x6b [<c033b1a7>] schedule+0x1f0/0x20a [<c01045e7>] common_interrupt+0x23/0x28
Kernel Panic - not syncing: Fatal exception in interrupt
makes it useful enough - at least for me.
The fact, that this information has not been used by the knowledgable developers of the offending code to fix the root cause within 14 days is a totaly different problem.
Thanks,
tglx
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