Re: WARNING: kmemcheck: Caught 32-bit read from uninitializedmemory (f6f6e1a4), by kmemleak's scan_block()

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> * Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
> 
> > On Tue, Aug 25, 2009 at 12:28 PM, Catalin
> > Marinas<catalin.marinas@xxxxxxx> wrote:
> > >> Does this look OK to you?
> > >
> > > For the kmemleak.c part:
> > >
> > > Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> > 
> > Vegard? Ingo? The patch is based on tip/out-of-tree so it probably 
> > should go to the kmemleak tree?
> 
> I'm testing it currently - but yeah, i'd agree that it should go 
> into the kmemleak tree, with a .32 merge date or so.

btw., i re-tested the original tree, and got the lockup/crash below.

	Ingo

--------------->
EXT3 FS on sdb1, internal journal
EXT3-fs: mounted filesystem with writeback data mode.
BUG: soft lockup - CPU#0 stuck for 61s! [kmemleak:3080]
irq event stamp: 6938907
hardirqs last  enabled at (6938906): [<c1e68535>] _write_unlock_irqrestore+0x55/0x70
hardirqs last disabled at (6938907): [<c102434f>] apic_timer_interrupt+0x2f/0x3c
softirqs last  enabled at (1776166): [<c106ba9c>] __do_softirq+0x1cc/0x200
softirqs last disabled at (1776357): [<c106bb2d>] do_softirq+0x5d/0x70

Pid: 3080, comm: kmemleak Not tainted (2.6.31-rc7-tip #1528) P4DC6
EIP: 0060:[<c1e68537>] EFLAGS: 00000282 CPU: 0
EIP is at _write_unlock_irqrestore+0x57/0x70
EAX: 0069e11a EBX: c2420d48 ECX: 00000002 EDX: 00000001
ESI: 00000282 EDI: c3526af8 EBP: f0c13df4 ESP: f0c13dec
 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
CR0: 8005003b CR2: f7840000 CR3: 1ffd3000 CR4: 000006f0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff4ff0 DR7: 00000400
Call Trace:
 [<c1103ade>] __delete_object+0x3e/0x90
 [<c1103b46>] delete_object_full+0x16/0x30
 [<c110491f>] kmemleak_free+0x5f/0x70
 [<c10fc2e3>] ? kmem_cache_free+0x43/0x160
 [<c10fc3b7>] kmem_cache_free+0x117/0x160
 [<c111c33b>] ? __d_free+0x2b/0x40
 [<c111c33b>] __d_free+0x2b/0x40
 [<c111cd1b>] d_callback+0xb/0x10
 [<c10b22ef>] rcu_process_callbacks+0x4f/0x70
 [<c106b9bf>] __do_softirq+0xef/0x200
 [<c108dd99>] ? tick_program_event+0x39/0x50
 [<c106bb2d>] do_softirq+0x5d/0x70
 [<c106c35d>] irq_exit+0x8d/0xa0
 [<c103bb86>] smp_apic_timer_interrupt+0x56/0x90
 [<c1424538>] ? trace_hardirqs_off_thunk+0xc/0x14
 [<c1024356>] apic_timer_interrupt+0x36/0x3c
 [<c109007b>] ? lockdep_free_key_range+0x12b/0x1c0
 [<c1e685f7>] ? _read_unlock_irqrestore+0x57/0x70
 [<c1103a1f>] find_and_get_object+0x5f/0xa0
 [<c1103f62>] scan_block+0x42/0x120
 [<c1104b70>] ? kmemleak_scan_thread+0x0/0xc0
 [<c11041fa>] kmemleak_scan+0xda/0x4f0
 [<c1104b70>] ? kmemleak_scan_thread+0x0/0xc0
 [<c1e66ea5>] ? mutex_lock_nested+0x35/0x40
 [<c1104b70>] ? kmemleak_scan_thread+0x0/0xc0
 [<c1104bc0>] kmemleak_scan_thread+0x50/0xc0
 [<c1080514>] kthread+0x74/0x80
 [<c10804a0>] ? kthread+0x0/0x80
 [<c102453b>] kernel_thread_helper+0x7/0x3c
Kernel panic - not syncing: softlockup: hung tasks
Pid: 3080, comm: kmemleak Not tainted 2.6.31-rc7-tip #1528
Call Trace:
 [<c1e654be>] ? printk+0x18/0x1a
 [<c1e653ee>] panic+0x4d/0x105
 [<c10acc16>] softlockup_tick+0x156/0x180
 [<c10717a7>] run_local_timers+0x17/0x20
 [<c10717df>] update_process_times+0x2f/0x70
 [<c108e1ed>] tick_nohz_handler+0x7d/0xf0
 [<c103bb81>] smp_apic_timer_interrupt+0x51/0x90
 [<c1424538>] ? trace_hardirqs_off_thunk+0xc/0x14
 [<c1024356>] apic_timer_interrupt+0x36/0x3c
 [<c109007b>] ? lockdep_free_key_range+0x12b/0x1c0
 [<c1e68537>] ? _write_unlock_irqrestore+0x57/0x70
 [<c1103ade>] __delete_object+0x3e/0x90
 [<c1103b46>] delete_object_full+0x16/0x30
 [<c110491f>] kmemleak_free+0x5f/0x70
 [<c10fc2e3>] ? kmem_cache_free+0x43/0x160
 [<c10fc3b7>] kmem_cache_free+0x117/0x160
 [<c111c33b>] ? __d_free+0x2b/0x40
 [<c111c33b>] __d_free+0x2b/0x40
 [<c111cd1b>] d_callback+0xb/0x10
 [<c10b22ef>] rcu_process_callbacks+0x4f/0x70
 [<c106b9bf>] __do_softirq+0xef/0x200
 [<c108dd99>] ? tick_program_event+0x39/0x50
 [<c106bb2d>] do_softirq+0x5d/0x70
 [<c106c35d>] irq_exit+0x8d/0xa0
 [<c103bb86>] smp_apic_timer_interrupt+0x56/0x90
 [<c1424538>] ? trace_hardirqs_off_thunk+0xc/0x14
 [<c1024356>] apic_timer_interrupt+0x36/0x3c
 [<c109007b>] ? lockdep_free_key_range+0x12b/0x1c0
 [<c1e685f7>] ? _read_unlock_irqrestore+0x57/0x70
 [<c1103a1f>] find_and_get_object+0x5f/0xa0
 [<c1103f62>] scan_block+0x42/0x120
 [<c1104b70>] ? kmemleak_scan_thread+0x0/0xc0
 [<c11041fa>] kmemleak_scan+0xda/0x4f0
 [<c1104b70>] ? kmemleak_scan_thread+0x0/0xc0
 [<c1e66ea5>] ? mutex_lock_nested+0x35/0x40
 [<c1104b70>] ? kmemleak_scan_thread+0x0/0xc0
 [<c1104bc0>] kmemleak_scan_thread+0x50/0xc0
 [<c1080514>] kthread+0x74/0x80
 [<c10804a0>] ? kthread+0x0/0x80
 [<c102453b>] kernel_thread_helper+0x7/0x3c
Rebooting in 1 seconds..Initializing cgroup subsys cpuset
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