linux-next: boot panic in serial init

linux-next: boot panic in serial init

[Stephen Rothwell]

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Hi Alan,

Today's linux-next on a pSeries PowerPC machine panics during boot like
this:

calling  .serial8250_init+0x0/0x230 @ 1
Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
------------[ cut here ]------------
kernel BUG at arch/powerpc/lib/locks.c:36!
cpu 0x0: Vector: 700 (Program Check) at [c0000000be683740]
    pc: c000000000039460: .__spin_yield+0x40/0x90
    lr: c000000000570284: ._spin_lock+0x84/0x90
    sp: c0000000be6839c0
   msr: 8000000000029032
  current = 0xc0000000be67e000
  paca    = 0xc000000000947200
    pid   = 1, comm = swapper
kernel BUG at arch/powerpc/lib/locks.c:36!
enter ? for help
[c0000000be683a30] c000000000570284 ._spin_lock+0x84/0x90
[c0000000be683ab0] c00000000056e75c .__mutex_lock_slowpath+0xec/0x2d0
[c0000000be683b90] c00000000056e274 .mutex_lock+0x54/0x60
[c0000000be683c10] c00000000032f6f8 .uart_add_one_port+0xd8/0x3f0
[c0000000be683d30] c0000000007a48c4 .serial8250_init+0x1a4/0x230
[c0000000be683de0] c00000000000947c .do_one_initcall+0x6c/0x1e0
[c0000000be683ee0] c000000000779d6c .kernel_init+0x23c/0x2c0
[c0000000be683f90] c00000000002a8e4 .kernel_thread+0x54/0x70

arch/powerpc/lib/locks.c line 36 is:

        lock_value = lock->slock;
        if (lock_value == 0)
                return;
        holder_cpu = lock_value & 0xffff;
        BUG_ON(holder_cpu >= NR_CPUS);

this last line.  Which would imply that the lock has probably not been
initialised.  Indeed, uart_add_one_port does:

	struct tty_port *port;

	mutex_lock(&port->mutex);

without assigning to port.  See "serial-move-mutex" from the ttydev tree.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: linux-next: boot panic in serial init

[Sachin Sant]

Stephen Rothwell wrote:
> Hi Alan,
>
> Today's linux-next on a pSeries PowerPC machine panics during boot like
> this:
>   
Similar problem on x86 as well.

Serial: 8250/16550 driver, 8 ports, IRQ sharing disabled
BUG: unable to handle kernel NULL pointer dereference at 0000000000000070
IP: [<ffffffff8132d15a>] mutex_lock+0xc/0x2d
PGD 0 
Oops: 0002 [#1] SMP 
last sysfs file: 
CPU 0 
Modules linked in:
Pid: 1, comm: swapper Not tainted 2.6.31-rc4-autotest-next-20090724-5-default #1 BladeCenter LS21 -[79716AA]-
RIP: 0010:[<ffffffff8132d15a>]  [<ffffffff8132d15a>] mutex_lock+0xc/0x2d
RSP: 0018:ffff88012b319da0  EFLAGS: 00010286
RAX: ffff88012b319e10 RBX: 0000000000000070 RCX: ffffffff85d06ad0
RDX: 0000000000000008 RSI: ffffffff85d06ad0 RDI: 0000000000000070
RBP: ffff88012b319db0 R08: 0000000000000001 R09: ffff88012b319d40
R10: 0000000300000000 R11: 0000000000018600 R12: ffffffff85d06ad0
R13: ffff88012846a000 R14: ffffffff8154bd00 R15: 0000000000000070
FS:  0000000000000000(0000) GS:ffff880028022000(0000) knlGS:0000000000000000
CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 0000000000000070 CR3: 0000000001001000 CR4: 00000000000006f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper (pid: 1, threadinfo ffff88012b318000, task ffff88012b316000)
Stack:
 ffff88012b319e10 00000000ffffffea ffff88012b319e40 ffffffff8126c572
<0> 0000000000000000 0000000000000000 ffff88012b319de0 ffffffff811e9ea7
<0> ffff8801284c6a10 ffff8801284c6a00 0000000000000000 00000000ffffffea
Call Trace:
 [<ffffffff8126c572>] uart_add_one_port+0x72/0x332
 [<ffffffff811e9ea7>] ? kobject_init+0x43/0x83
 [<ffffffff81686a2e>] ? serial8250_init+0x0/0x143
 [<ffffffff81686b2c>] serial8250_init+0xfe/0x143
 [<ffffffff8100905c>] do_one_initcall+0x56/0x12b
 [<ffffffff8108b3ca>] ? register_irq_proc+0xb0/0xcc
 [<ffffffff81120000>] ? sys_quotactl+0x7c/0x748
 [<ffffffff8165b691>] kernel_init+0x181/0x1db
 [<ffffffff8100ca1a>] child_rip+0xa/0x20
 [<ffffffff8165b510>] ? kernel_init+0x0/0x1db
 [<ffffffff8100ca10>] ? child_rip+0x0/0x20
Code: c0 b0 b1 05 81 48 89 45 c8 48 89 45 d0 e8 1d ff ff ff 48 83 c4 40 5b 41 5c 41 5d 41 5e c9 c3 55 48 89 e5 53 48 89 fb 48 83 ec 08 <f0> ff 0f 79 05 e8 97 00 00 00 65 48 8b 04 25 b8 b4 00 00 48 2d 
RIP  [<ffffffff8132d15a>] mutex_lock+0xc/0x2d
 RSP <ffff88012b319da0>
CR2: 0000000000000070
---[ end trace b19b3a85649e706b ]---

Thanks
-Sachin


-- 

---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
---------------------------------

Re: linux-next: boot panic in serial init

[Alan Cox]

On Fri, 24 Jul 2009 16:35:01 +0530
Sachin Sant <sachinp@in.ibm.com> wrote:

> Stephen Rothwell wrote:
> > Hi Alan,
> >
> > Today's linux-next on a pSeries PowerPC machine panics during boot like
> > this:
> >   
> Similar problem on x86 as well.

Screw up on my part. New patches will get rsynced shortly.

Alan

Re: linux-next: boot panic in serial init

[Stephen Rothwell]

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Hi Alan,

On Fri, 24 Jul 2009 13:15:45 +0100 Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
>
> Screw up on my part. New patches will get rsynced shortly.

Thanks.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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