[next-20190507][powerpc] WARN kernel/cgroup/cgroup.c:6008 with LTP ptrace01 test case

[Roman Gushchin]

On Wed, May 08, 2019 at 03:06:30PM +0530, Sachin Sant wrote:
> While running LTP tests(specifically ptrace01) following WARNING is observed
> on POWER8 LPAR running next-20190507 built using 4K page size.
> 
> [ 3969.979492] msgrcv04 (433) used greatest stack depth: 9328 bytes left
> [ 3981.452911] madvise06 (515): drop_caches: 3
> [ 4004.575752] WARNING: CPU: 5 PID: 721 at kernel/cgroup/cgroup.c:6008 cgroup_exit+0x2ac/0x2c0
> [ 4004.575781] Modules linked in: overlay rpadlpar_io rpaphp iptable_mangle xt_MASQUERADE iptable_nat nf_nat xt_conntrack nf_conntrack nf_defrag_ipv4 ipt_REJECT nf_reject_ipv4 xt_tcpudp tun bridge stp llc kvm iptable_filter pseries_rng rng_core vmx_crypto ip_tables x_tables autofs4 [last unloaded: dummy_del_mod]
> [ 4004.575837] CPU: 5 PID: 721 Comm: ptrace01 Tainted: G           O      5.1.0-next-20190507-autotest #1
> [ 4004.575846] NIP:  c000000001b3026c LR: c000000001b30054 CTR: c000000001c9f020
> [ 4004.575855] REGS: c000000171fff840 TRAP: 0700   Tainted: G           O       (5.1.0-next-20190507-autotest)
> [ 4004.575863] MSR:  800000010282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE,TM[E]>  CR: 44004824  XER: 20000000
> [ 4004.575885] CFAR: c000000001b30078 IRQMASK: 1 
> [ 4004.575885] GPR00: c000000001b30054 c000000171fffad0 c000000003938700 c00000027b02fa18 
> [ 4004.575885] GPR04: c00000027b02fa00 0000000000000000 c000000003ae8700 00000000001c180a 
> [ 4004.575885] GPR08: 0000000000000001 0000000000000001 c000000003ae8700 0000000000000001 
> [ 4004.575885] GPR12: 0000000000004400 c00000001ec7ea80 c000000003a4d670 0000000000000009 
> [ 4004.575885] GPR16: 0000000000000000 0000000000040100 00000000418004fc 0000000008430000 
> [ 4004.575885] GPR20: 0000000000000009 0000000000000001 c0000001715e9200 c00000016d8f4d00 
> [ 4004.575885] GPR24: c000000171fffd90 0000000000000100 c000000168692478 c000000171fffb98 
> [ 4004.575885] GPR28: c000000168692400 c00000016d8f4d00 c0000000036420d0 c00000027b02fa00 
> [ 4004.575958] NIP [c000000001b3026c] cgroup_exit+0x2ac/0x2c0
> [ 4004.575966] LR [c000000001b30054] cgroup_exit+0x94/0x2c0
> [ 4004.575972] Call Trace:
> [ 4004.575979] [c000000171fffad0] [c000000001b30054] cgroup_exit+0x94/0x2c0 (unreliable)
> [ 4004.575990] [c000000171fffb30] [c0000000019cea98] do_exit+0x878/0x1ae0
> [ 4004.575999] [c000000171fffc00] [c0000000019cfe4c] do_group_exit+0xac/0x1d0
> [ 4004.576009] [c000000171fffc40] [c0000000019ed00c] get_signal+0x2bc/0x11c0
> [ 4004.576019] [c000000171fffd30] [c000000001867b14] do_notify_resume+0x384/0x900
> [ 4004.576029] [c000000171fffe20] [c00000000183e844] ret_from_except_lite+0x70/0x74
> [ 4004.576037] Instruction dump:
> [ 4004.576043] 314a0001 7d40492d 40c2fff4 3d42001b e92a7288 39290001 f92a7288 4bfffe5c 
> [ 4004.576056] 3d42001b e92a7258 39290001 f92a7258 <0fe00000> 4bfffe0c 4be91e45 60000000 
> [ 4004.576071] ---[ end trace 82a1a7c19005ebd6 ]—
> 
> The WARN_ONCE was added by following commit 
> 96b9c592def5 ("cgroup: get rid of cgroup_freezer_frozen_exit()”). 
> 
> Reverting the patch helps avoid the warning.

Hi Sachin!

Thank you for the report!

Can you, please, check that the patch at https://lkml.org/lkml/2019/5/8/938
solves the problem?

I'll appreciate it!

Thanks!

Roman