Re: vmstat: On demand vmstat workers V8
From: Sasha Levin
Date: Fri Jul 25 2014 - 22:24:27 EST
On 07/10/2014 10:04 AM, Christoph Lameter wrote:
> This patch creates a vmstat shepherd worker that monitors the
> per cpu differentials on all processors. If there are differentials
> on a processor then a vmstat worker local to the processors
> with the differentials is created. That worker will then start
> folding the diffs in regular intervals. Should the worker
> find that there is no work to be done then it will make the shepherd
> worker monitor the differentials again.
Hi Christoph, all,
This patch doesn't interact well with my fuzzing setup. I'm seeing
the following:
[ 490.446927] BUG: using __this_cpu_read() in preemptible [00000000] code: kworker/16:1/7368
[ 490.447909] caller is __this_cpu_preempt_check+0x13/0x20
[ 490.448596] CPU: 8 PID: 7368 Comm: kworker/16:1 Not tainted 3.16.0-rc6-next-20140725-sasha-00047-g9eb9a52 #933
[ 490.449847] Workqueue: events vmstat_update
[ 490.450558] ffffffff97383bb6 0000000000000000 ffffffff9727df83 ffff8803077cfb68
[ 490.451520] ffffffff95dc96b3 0000000000000008 ffff8803077cfba0 ffffffff92002438
[ 490.452475] ffff8803077cfc80 ffff880be21ea138 ffff8803077cfc80 00000000001e6a48
[ 490.453459] Call Trace:
[ 490.453776] dump_stack (lib/dump_stack.c:52)
[ 490.454394] check_preemption_disabled (lib/smp_processor_id.c:46)
[ 490.455161] __this_cpu_preempt_check (lib/smp_processor_id.c:63)
[ 490.455927] refresh_cpu_vm_stats (mm/vmstat.c:492)
[ 490.456753] vmstat_update (mm/vmstat.c:1252)
[ 490.457463] process_one_work (kernel/workqueue.c:2022 include/linux/jump_label.h:115 include/trace/events/workqueue.h:111 kernel/workqueue.c:2027)
[ 490.458159] ? process_one_work (include/linux/workqueue.h:185 kernel/workqueue.c:598 kernel/workqueue.c:625 kernel/workqueue.c:2015)
[ 490.458887] worker_thread (include/linux/list.h:188 kernel/workqueue.c:2154)
[ 490.459555] ? __schedule (./arch/x86/include/asm/bitops.h:311 include/linux/thread_info.h:91 include/linux/sched.h:2854 kernel/sched/core.c:2825)
[ 490.460370] ? process_one_work (kernel/workqueue.c:2098)
[ 490.461177] kthread (kernel/kthread.c:207)
[ 490.461792] ? flush_kthread_work (kernel/kthread.c:176)
[ 490.462529] ret_from_fork (arch/x86/kernel/entry_64.S:348)
[ 490.463181] ? flush_kthread_work (kernel/kthread.c:176)
[ 490.464008] ------------[ cut here ]------------
[ 490.464613] kernel BUG at mm/vmstat.c:1278!
[ 490.465116] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 490.465981] Dumping ftrace buffer:
[ 490.466585] (ftrace buffer empty)
[ 490.467030] Modules linked in:
[ 490.467429] CPU: 8 PID: 7368 Comm: kworker/16:1 Not tainted 3.16.0-rc6-next-20140725-sasha-00047-g9eb9a52 #933
[ 490.468641] Workqueue: events vmstat_update
[ 490.469163] task: ffff88030772b000 ti: ffff8803077cc000 task.ti: ffff8803077cc000
[ 490.470033] RIP: vmstat_update (mm/vmstat.c:1278)
[ 490.470269] RSP: 0000:ffff8803077cfcb8 EFLAGS: 00010287
[ 490.470269] RAX: ffff87ffffffffff RBX: 0000000000000008 RCX: 0000000000000000
[ 490.470269] RDX: ffff88030772bcf8 RSI: ffffffff972e5fd0 RDI: ffffffff986fa5d0
[ 490.470269] RBP: ffff8803077cfcd0 R08: 0000000000000002 R09: 0000000000000000
[ 490.470269] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8805fa7e34d0
[ 490.470269] R13: ffff8803117e2240 R14: 0000000000000800 R15: 0000000000000000
[ 490.470269] FS: 0000000000000000(0000) GS:ffff880311200000(0000) knlGS:0000000000000000
[ 490.470269] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 490.470269] CR2: 00007fffc67fef1a CR3: 0000000017a22000 CR4: 00000000000006a0
[ 490.470269] Stack:
[ 490.470269] ffff8803117dd240 ffff88030af938e0 ffff8803117e2240 ffff8803077cfd88
[ 490.470269] ffffffff911f45f5 ffffffff911f455d ffff88030af93928 ffff88031081e900
[ 490.470269] ffff88030af938f0 ffff88030af93900 ffff88030af938e8 ffff88030af938f8
[ 490.470269] Call Trace:
[ 490.470269] process_one_work (kernel/workqueue.c:2022 include/linux/jump_label.h:115 include/trace/events/workqueue.h:111 kernel/workqueue.c:2027)
[ 490.470269] ? process_one_work (include/linux/workqueue.h:185 kernel/workqueue.c:598 kernel/workqueue.c:625 kernel/workqueue.c:2015)
[ 490.470269] worker_thread (include/linux/list.h:188 kernel/workqueue.c:2154)
[ 490.470269] ? __schedule (./arch/x86/include/asm/bitops.h:311 include/linux/thread_info.h:91 include/linux/sched.h:2854 kernel/sched/core.c:2825)
[ 490.470269] ? process_one_work (kernel/workqueue.c:2098)
[ 490.470269] kthread (kernel/kthread.c:207)
[ 490.470269] ? flush_kthread_work (kernel/kthread.c:176)
[ 490.470269] ret_from_fork (arch/x86/kernel/entry_64.S:348)
[ 490.470269] ? flush_kthread_work (kernel/kthread.c:176)
[ 490.470269] Code: c7 d0 a5 6f 98 89 c3 e8 9f 9e 08 00 3b 1d 89 8b 35 07 73 7f f0 49 0f ab 1c 24 72 0f 5b 41 5c 41 5d 5d c3 0f 1f 84 00 00 00 00 00 <0f> 0b 66 0f 1f 44 00 00 48 63 3d f1 be 36 07 48 c7 c3 40 d2 1d
All code
========
0: c7 (bad)
1: d0 a5 6f 98 89 c3 shlb -0x3c766791(%rbp)
7: e8 9f 9e 08 00 callq 0x89eab
c: 3b 1d 89 8b 35 07 cmp 0x7358b89(%rip),%ebx # 0x7358b9b
12: 73 7f jae 0x93
14: f0 49 0f ab 1c 24 lock bts %rbx,(%r12)
1a: 72 0f jb 0x2b
1c: 5b pop %rbx
1d: 41 5c pop %r12
1f: 41 5d pop %r13
21: 5d pop %rbp
22: c3 retq
23: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
2a: 00
2b:* 0f 0b ud2 <-- trapping instruction
2d: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
33: 48 63 3d f1 be 36 07 movslq 0x736bef1(%rip),%rdi # 0x736bf2b
3a: 48 c7 c3 40 d2 1d 00 mov $0x1dd240,%rbx
Code starting with the faulting instruction
===========================================
0: 0f 0b ud2
2: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
8: 48 63 3d f1 be 36 07 movslq 0x736bef1(%rip),%rdi # 0x736bf00
f: 48 c7 c3 40 d2 1d 00 mov $0x1dd240,%rbx
[ 490.470269] RIP vmstat_update (mm/vmstat.c:1278)
[ 490.470269] RSP <ffff8803077cfcb8>
Thanks,
Sasha
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