Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> writes:

> Hello, Linus.
>
> This pull request contains two patches, both of which aren't fixes
> per-se but I think it'd be better to fast-track them.
>
Darn.  I was hoping to see a fix for the bug I just tripped over,
that results in a process stuck in short term disk wait.

Using the memory control group for it's designed function aka killing
processes that eats too much memory I just would up with an unkillable
process in 3.11-rc2.

I am really not certain what is going on although I haven't rebooted the
machine yet so I can look a bit further if someone has a good idea.

On the unkillable task I see.

/proc/<pid>/stack:

[<ffffffff8110342c>] mem_cgroup_iter+0x1e/0x1d2
[<ffffffff81105630>] __mem_cgroup_try_charge+0x779/0x8f9
[<ffffffff81070d46>] ktime_get_ts+0x36/0x74
[<ffffffff81104d84>] memcg_oom_wake_function+0x0/0x5a
[<ffffffff8110620c>] __mem_cgroup_try_charge_swapin+0x6c/0xac
[<ffffffff810dedce>] handle_pte_fault+0x483/0x760
[<ffffffff8137c4f2>] __do_page_fault+0x374/0x3bc
[<ffffffff810c539c>] __rmqueue+0x82/0x24c
[<ffffffff810d6404>] __inc_zone_state+0x3f/0x47
[<ffffffff8137e3ca>] kprobe_flush_task+0x76/0xbe
[<ffffffff813798b2>] page_fault+0x22/0x30
[<ffffffff811cc3ef>] __get_user_8+0x1f/0x29
[<ffffffff8107a61b>] exit_robust_list+0x2d/0x11b
[<ffffffff81034005>] mm_release+0x18/0xee
[<ffffffff8103ab4b>] do_exit+0x24a/0x90c
[<ffffffff8103b299>] do_group_exit+0x67/0x99
[<ffffffff810463c8>] get_signal_to_deliver+0x479/0x4ad
[<ffffffff8100209f>] do_signal+0x3c/0x434
[<ffffffff810e5571>] mprotect_fixup+0x1b9/0x1f3
[<ffffffff8107afed>] SyS_futex+0x12e/0x161
[<ffffffff810024bc>] do_notify_resume+0x25/0x68
[<ffffffff8137e99a>] int_signal+0x12/0x17
[<ffffffffffffffff>] 0xffffffffffffffff


/proc/<pid>/status:
Name:   balloon-executo
State:  D (disk sleep)
Tgid:   14723
Pid:    14723
PPid:   14718
TracerPid:      0
Uid:    0       0       0       0
Gid:    0       0       0       0
FDSize: 64
Groups: 0 
VmPeak:   397748 kB
VmSize:   397748 kB
VmLck:    131072 kB
VmPin:         0 kB
VmHWM:    108008 kB
VmRSS:    108008 kB
VmData:   303772 kB
VmStk:       136 kB
VmExe:        24 kB
VmLib:     28952 kB
VmPTE:       424 kB
VmSwap:     2132 kB
Threads:        1
SigQ:   2/60699
SigPnd: 0000000000000000
ShdPnd: 0000000000004100
SigBlk: 0000000000000000
SigIgn: 0000000000000006
SigCgt: 0000000180000000
CapInh: 0000000000000000
CapPrm: 0000001fffffffff
CapEff: 0000001fffffffff
CapBnd: 0000001fffffffff
Seccomp:        0
Cpus_allowed:   ff
Cpus_allowed_list:      0-7
Mems_allowed:   00000000,00000001
Mems_allowed_list:      0
voluntary_ctxt_switches:        13
nonvoluntary_ctxt_switches:     1