Re: [PATCH 2.6.20-rc1 00/10] Kernel memory leak detector 0.13

["Catalin Marinas" <catalin.marinas@gmail.com>]

On 17/12/06, Ingo Molnar <mingo@elte.hu> wrote:
> it would be nice to record 1) the jiffies value at the time of
> allocation, 2) the PID and the comm of the task that did the allocation.
> The jiffies timestamp would be useful to see the age of the allocation,
> and the PID/comm is useful for context.

Trying to copy the comm with get_task_comm, I get the lockdep report
below, caused by acquiring the task's alloc_lock. Any idea how to go
around this?

=================================
[ INFO: inconsistent lock state ]
2.6.20-rc2 #211
---------------------------------
inconsistent {hardirq-on-W} -> {in-hardirq-W} usage.
swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
(init_task.alloc_lock){+-..}, at: [<c007d950>] get_task_comm+0x24/0x40
{hardirq-on-W} state was registered at:
 [<c00493d0>] lock_acquire+0x80/0x94
 [<c020cf1c>] _spin_lock+0x30/0x40
 [<c0027c80>] copy_process+0x8b8/0x1208
 [<c0028874>] do_fork+0xc0/0x1e0
 [<c001497c>] kernel_thread+0x70/0x80
 [<c000f864>] rest_init+0x1c/0x30
 [<c000fa9c>] start_kernel+0x224/0x27c
 [<00008078>] 0x8078
irq event stamp: 33758
hardirqs last  enabled at (33757): [<c0014ef8>] default_idle+0x44/0x50
hardirqs last disabled at (33758): [<c00131d4>] __irq_svc+0x34/0xc0
softirqs last  enabled at (33750): [<c002f97c>] __do_softirq+0x10c/0x124
softirqs last disabled at (33745): [<c002fde0>] irq_exit+0x58/0x60

other info that might help us debug this:
1 lock held by swapper/0:
#0:  (&lp->lock){+...}, at: [<c0146b9c>] smc_interrupt+0x28/0x784

stack backtrace:
[<c0018cf4>] (dump_stack+0x0/0x14) from [<c00471b4>]
(print_usage_bug+0x11c/0x154)
[<c0047098>] (print_usage_bug+0x0/0x154) from [<c0047b60>]
(mark_lock+0xe0/0x4c8)
r8 = 00000001  r7 = C02A4348  r6 = 00000000  r5 = 00000002
r4 = C02A4638
[<c0047a80>] (mark_lock+0x0/0x4c8) from [<c0048b34>]
(__lock_acquire+0x424/0xc40)
[<c0048710>] (__lock_acquire+0x0/0xc40) from [<c00493d0>]
(lock_acquire+0x80/0x94)
[<c0049350>] (lock_acquire+0x0/0x94) from [<c020cf1c>] (_spin_lock+0x30/0x40)
[<c020ceec>] (_spin_lock+0x0/0x40) from [<c007d950>] (get_task_comm+0x24/0x40)
r4 = C02A4348
[<c007d92c>] (get_task_comm+0x0/0x40) from [<c0075570>]
(memleak_alloc+0x168/0x2b4)
r6 = C7596E60  r5 = A0000193  r4 = C7596E64
[<c0075408>] (memleak_alloc+0x0/0x2b4) from [<c0072800>]
(kmem_cache_alloc+0x110/0x124)
[<c00726f0>] (kmem_cache_alloc+0x0/0x124) from [<c0199228>]
(__alloc_skb+0x34/0x130)
[<c01991f4>] (__alloc_skb+0x0/0x130) from [<c0146f04>]
(smc_interrupt+0x390/0x784)
[<c0146b74>] (smc_interrupt+0x0/0x784) from [<c005322c>]
(handle_IRQ_event+0x2c/0x68)
[<c0053200>] (handle_IRQ_event+0x0/0x68) from [<c0054d94>]
(handle_level_irq+0xe4/0x150)
r7 = C02A1128  r6 = C7805C20  r5 = 00000029  r4 = C02A1100
[<c0054cb0>] (handle_level_irq+0x0/0x150) from [<c001469c>]
(asm_do_IRQ+0x70/0x9c)
r7 = 00008000  r6 = 00000029  r5 = 00000000  r4 = C029E000
[<c001462c>] (asm_do_IRQ+0x0/0x9c) from [<c00131d4>] (__irq_svc+0x34/0xc0)
r5 = FF000100  r4 = FFFFFFFF
[<c0014eb4>] (default_idle+0x0/0x50) from [<c0014cb0>] (cpu_idle+0x30/0x4c)
[<c0014c80>] (cpu_idle+0x0/0x4c) from [<c000f870>] (rest_init+0x28/0x30)
r5 = C02C3D30  r4 = C04DB2A4
[<c000f848>] (rest_init+0x0/0x30) from [<c000fa9c>] (start_kernel+0x224/0x27c)
[<c000f878>] (start_kernel+0x0/0x27c) from [<00008078>] (0x8078)

--
Catalin
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