[Devel] [PATCH 00/17] Pid-NS(V3) Enable multiple pid namespaces

[sukadev at us.ibm.com]

Alexey Dobriyan [adobriyan at sw.ru] wrote:
| It crashed while playing with your version of pid namespaces.

Thanks. I think I found the race and am working on a fix.

| 
| We created namespace, entered it, run perf.c benchmark
| and mount /proc; umount /proc loop.

I had a similar loop of a test that created a namespace, mounted /proc,
created 10 processes, umounted /proc and exited the ns. It somehow did
not catch this. Am still trying to repro.

Suka

| 
| 
| BUG: unable to handle kernel NULL pointer dereference at virtual address 0000004c
|  printing eip:
| *pde = 00000000
| Oops: 0000 [#1]
| SMP 
| Modules linked in: sbs button battery ac sky2 e1000 ata_piix libata sd_mod scsi_mod
| CPU:    1
| EIP:    0060:[<c0465fb2>]    Not tainted VLI
| EFLAGS: 00010246   (2.6.22-rc4-mm2-pidns-y #2)
| EIP is at d_hash_and_lookup+0x36/0x63
| eax: 00135738   ebx: c52bff30   ecx: ffffffff   edx: 00000003
| esi: c52bff1c   edi: 00d4bf68   ebp: 00000000   esp: c52bfef0
| ds: 007b   es: 007b   fs: 00d8  gs: 0000  ss: 0068
| Process perf (pid: 29058, ti=c52be000 task=c52b4370 task.ti=c52be000)
| Stack: 00000000 c40dc0c0 c52b4370 00000000 c52bff2c c0480225 c52bff2c 0000000d 
|        c05d7a23 000019af 00000001 00d4bf68 00000004 c52bff2c 00000000 35373536 
|        00000000 00000000 3a221caa c4716e80 c4716eb0 00000001 c52b4370 c048032f 
| Call Trace:
|  [<c0480225>] proc_flush_task_from_pid_ns+0xf5/0x1d7
|  [<c048032f>] proc_flush_task+0x28/0x2f
|  [<c041ce15>] release_task+0xc/0xcb
|  [<c041dc1a>] exit_notify+0x229/0x230
|  [<c041df5d>] do_exit+0x33c/0x392
|  [<c041dfd3>] do_group_exit+0x0/0x6d
|  [<c0402500>] syscall_call+0x7/0xb
|  =======================
| Code: c7 04 24 00 00 00 00 8b 5a 08 8b 4a 04 49 83 f9 ff 74 16 0f b6 13 43 89 d0 c1 e0 04 8d 04 07 c1 ea 04 01 d0 6b f8 0b eb e4 89 3e <8b> 45 4c 85 c0 74 11 8b 48 04 85 c9 74 0a 89 f2 89 e8 ff d1 85 
| EIP: [<c0465fb2>] d_hash_and_lookup+0x36/0x63 SS:ESP 0068:c52bfef0