On Tue, 2014-05-13 at 17:40 +0200, Sebastian Andrzej Siewior wrote:
> * Mike Galbraith | 2014-05-10 06:15:03 [+0200]:
>
> >On Fri, 2014-05-09 at 20:12 +0200, Sebastian Andrzej Siewior wrote:
> >
> >> Known issues:
> >>
> >> - bcache is disabled.
> >>
> >> - lazy preempt on x86_64 leads to a crash with some load.
> >
> >That is only with NO_HZ_FUL enabled here. Box blows the stack during
> >task exit, eyeballing hasn't spotted the why.
>
> Even if I disable NO_HZ_FULL it explodes as soon as hackbench starts.
Well good, that makes a hell of a lot more sense. The below is with
NO_HZ_FULL enabled, and hackbench exploding on exit. Every kaboom I've
see has been a dead task exploding on scrambled thread_info.
Accessing per-anti-cpu data doesn't work well from our universe ;-)
crash> bt 6657
PID: 6657 TASK: ffff8801f947ac00 CPU: 1 COMMAND: "hackbench"
#0 [ffff88022fc86e00] crash_nmi_callback at ffffffff8102b8f4
#1 [ffff88022fc86e10] nmi_handle at ffffffff8164865a
#2 [ffff88022fc86ea0] default_do_nmi at ffffffff81648883
#3 [ffff88022fc86ed0] do_nmi at ffffffff81648b50
#4 [ffff88022fc86ef0] end_repeat_nmi at ffffffff81647b71
[exception RIP: oops_begin+162]
RIP: ffffffff816483e2 RSP: ffff8800b220d9d8 RFLAGS: 00000097
RAX: 0000000000000010 RBX: 0000000000000010 RCX: 0000000000000097
RDX: ffff8800b220d9d8 RSI: 0000000000000018 RDI: 0000000000000001
RBP: ffffffff816483e2 R8: ffffffff816483e2 R9: 0000000000000018
R10: ffff8800b220d9d8 R11: 0000000000000097 R12: ffffffffffffffff
R13: ffff88022700bf00 R14: 0000000000000100 R15: 0000000000000001
ORIG_RAX: 0000000000000001 CS: 0010 SS: 0018
--- <NMI exception stack> ---
#5 [ffff8800b220d9d8] oops_begin at ffffffff816483e2
#6 [ffff8800b220d9f0] no_context at ffffffff8162ef25
#7 [ffff8800b220da40] __bad_area_nosemaphore at ffffffff8162f19d
#8 [ffff8800b220daa0] bad_area_nosemaphore at ffffffff8162f1ca
#9 [ffff8800b220dab0] __do_page_fault at ffffffff8164a68e
#10 [ffff8800b220dbd0] do_page_fault at ffffffff8164ab9e
#11 [ffff8800b220dc00] page_fault at ffffffff81647808
[exception RIP: cpuacct_charge+148]
RIP: ffffffff810a1874 RSP: ffff8800b220dcb8 RFLAGS: 00010046
RAX: 0000000000000040 RBX: 000000000000dd08 RCX: 0000000000000003
RDX: 0000000000000006 RSI: 0000000000000006 RDI: ffff88022700bf00
RBP: ffff8800b220dcf8 R8: 00000000000006c0 R9: 000000000000000b
R10: 0000000000000000 R11: 0000000000013f40 R12: ffffffff81c3b180
R13: ffff8801f947ac00 R14: ffffffffb220ddd8 R15: 0000000000001d64
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#12 [ffff8800b220dd00] update_curr at ffffffff81092451
#13 [ffff8800b220dd60] dequeue_entity at ffffffff810928f3
#14 [ffff8800b220ddc0] dequeue_task_fair at ffffffff81092d4d
#15 [ffff8800b220de10] dequeue_task at ffffffff8108442e
#16 [ffff8800b220de40] deactivate_task at ffffffff81084f9e
#17 [ffff8800b220de50] __schedule at ffffffff816440d4
#18 [ffff8800b220ded0] schedule at ffffffff81644899
#19 [ffff8800b220def0] do_exit at ffffffff810530d0
#20 [ffff8800b220df40] do_group_exit at ffffffff8105334c
#21 [ffff8800b220df70] sys_exit_group at ffffffff810533e2
#22 [ffff8800b220df80] tracesys at ffffffff8164f109 (via system_call)
RIP: 00007fcc1a078ca8 RSP: 00007fff62546c48 RFLAGS: 00000246
RAX: ffffffffffffffda RBX: ffffffff8164f109 RCX: ffffffffffffffff
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00007fcc1a355840 R8: 00000000000000e7 R9: ffffffffffffffa8
R10: 00007fcc1a969700 R11: 0000000000000246 R12: ffffffff810533e2
R13: ffff8800b220df78 R14: 0000000001ad9c88 R15: 0000000000000001
ORIG_RAX: 00000000000000e7 CS: 0033 SS: 002b
crash> struct thread_info 0xffff8800b220c000
struct thread_info {
task = 0xffffffff,
exec_domain = 0xffffffff811bae66 <__d_free+70>,
flags = 2,
status = 0,
cpu = 2988498392,
saved_preempt_count = -30720,
preempt_lazy_count = -112742225,
addr_limit = {
seg = 524802
},
restart_block = {
fn = 0xffff88022fc91358,
{
futex = {
uaddr = 0x80202,
val = 3,
flags = 0,
bitset = 2988490752,
time = 18446744071585425101,
uaddr2 = 0xffff88022fc91358
},
nanosleep = {
clockid = 524802,
rmtp = 0x3,
compat_rmtp = 0xffff8800b220c000,
expires = 18446744071585425101
},
poll = {
ufds = 0x80202,
nfds = 3,
has_timeout = 0,
tv_sec = 18446612135302709248,
tv_nsec = 18446744071585425101
}
}
},
sysenter_return = 0xffffffff,
sig_on_uaccess_error = 0,
uaccess_err = 0
}
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