Re: + proc-dont-lock-task_structs-indefinitely-cpuset-fix-2.patch added to -mm tree

[Paul Jackson <pj@sgi.com>]

Eric wrote:
> I can kill a kernel this way as well.  Thanks this looks like
> a good reproducer I will see if  I can figure out why.

I suspect two problems, one with your patches that the fuser provokes,
and a separate bug earlier in *-mm that the DEBUG options noted below
provoke.

Details:

In addition to the problem that shows up with the three patches
>     proc-dont-lock-task_structs-indefinitely.patch
>     proc-dont-lock-task_structs-indefinitely-git-nfs-fix.patch
>     proc-dont-lock-task_structs-indefinitely-cpuset-fix.patch

when running the fuser command:
>     /bin/fuser -n tcp 5553

I am seeing as a separate bug the crash during boot that I reported
last, when I turned on some DEBUG options.  That crash occurs even with
none of your proc patches.

That is, to be specific, with this patch at the top of my applied stack:
     rtc-subsystem-rs5c372-driver.patch

and these patches at the front of my unapplied queue:
     trivial-cleanup-to-proc_check_chroot.patch
     proc-fix-the-inode-number-on-proc-pid-fd.patch

and the debug options:
> CONFIG_DEBUG_SLAB=y
> CONFIG_DEBUG_SPINLOCK=y
> CONFIG_DEBUG_SPINLOCK_SLEEP=y

I die during system boot with:
==============================

...
pci_hotplug: PCI Hot Plug PCI Core version: 0.5
SGI Altix RTC Timer: v2.1, 20 MHz
EFI Time Services Driver v0.4
Linux agpgart interface v0.101 (c) Dave Jones
sn_console: Console driver init
ttySG0 at I/O 0x0 (irq = 0) is a SGI SN L1
Unable to handle kernel NULL pointer dereference (address 0000000000000058)
swapper[1]: Oops 8813272891392 [1]
Modules linked in:

Pid: 1, CPU 0, comm:              swapper
psr : 0000101008026018 ifs : 800000000000040b ip  : [<a0000001001f0a50>]    Not tainted
ip is at sysfs_create_group+0x30/0x2a0
unat: 0000000000000000 pfs : 0000000000000308 rsc : 0000000000000003
rnat: 0000000002000027 bsps: 0000000000000002 pr  : 0000000000005649
ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c8a70433f
csd : 0000000000000000 ssd : 0000000000000000
b0  : a00000010081ad30 b6  : e000023002310080 b7  : a00000010081ad80
f6  : 1003e0000000000000000 f7  : 1003e20c49ba5e353f7cf
f8  : 1003e0000000000002ff0 f9  : 1003e0000000000000068
f10 : 1003e0000000000000000 f11 : 1003e0000000000000000
r1  : a000000100c93ab0 r2  : 0000000000000058 r3  : a000000100aa3560
r8  : 0000000000000000 r9  : a000000100cba7a0 r10 : ffffffffffffffff
r11 : 0000000000000400 r12 : e00002343bdb7d50 r13 : e00002343bdb0000
r14 : a000000100aa8300 r15 : a000000100cba7a0 r16 : a000000100aa3568
r17 : 00000000000003c0 r18 : 0000000000000001 r19 : 0000000000000002
r20 : ffffffffffffffff r21 : 000000000000000e r22 : 0000000000000000
r23 : a000000100a94eb8 r24 : a000000100824c80 r25 : a000000100aa3b18
r26 : 0000000000004000 r27 : a000000100913e80 r28 : e00002343b2d3918
r29 : 0000000000000001 r30 : a0000001007d9228 r31 : a00000010081ad80

Call Trace:
 [<a000000100013280>] show_stack+0x40/0xa0
                                sp=e00002343bdb78e0 bsp=e00002343bdb1298
 [<a000000100013ab0>] show_regs+0x7d0/0x800
                                sp=e00002343bdb7ab0 bsp=e00002343bdb1248
 [<a000000100036970>] die+0x210/0x320
                                sp=e00002343bdb7ab0 bsp=e00002343bdb1200
 [<a00000010005a800>] ia64_do_page_fault+0x900/0xa80
                                sp=e00002343bdb7ad0 bsp=e00002343bdb1198
 [<a00000010000bbc0>] ia64_leave_kernel+0x0/0x290
                                sp=e00002343bdb7b80 bsp=e00002343bdb1198
 [<a0000001001f0a50>] sysfs_create_group+0x30/0x2a0
                                sp=e00002343bdb7d50 bsp=e00002343bdb1140
 [<a00000010081ad30>] topology_cpu_callback+0x70/0xc0
                                sp=e00002343bdb7d60 bsp=e00002343bdb1110
 [<a00000010081ae00>] topology_sysfs_init+0x80/0x120
                                sp=e00002343bdb7d60 bsp=e00002343bdb10f0
 [<a000000100009860>] init+0x580/0x8e0
                                sp=e00002343bdb7d60 bsp=e00002343bdb10c8
 [<a000000100011740>] kernel_thread_helper+0xe0/0x100
                                sp=e00002343bdb7e30 bsp=e00002343bdb10a0
 [<a000000100009140>] start_kernel_thread+0x20/0x40
                                sp=e00002343bdb7e30 bsp=e00002343bdb10a0
 <0>Kernel panic - not syncing: Attempted to kill init!


-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.925.600.0401
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