> This patches are un-changloged, un-compiled, un-booted, un-tested,
> they are just shits, I even hope them un-sent or blocked.
>
> The patches include two -solutions-:
>
> Shit_A:
> workqueue: reset pool->node and unhash the pool when the node is
> offline
> update wq_numa when cpu_present_mask changed
>
> kernel/workqueue.c | 107
> +++++++++++++++++++++++++++++++++++++++++------------
> 1 file changed, 84 insertions(+), 23 deletions(-)
>
>
> Shit_B:
> workqueue: reset pool->node and unhash the pool when the node is
> offline
> workqueue: remove wq_numa_possible_cpumask
> workqueue: directly update attrs of pools when cpu hot[un]plug
>
> kernel/workqueue.c | 135
> +++++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 101 insertions(+), 34 deletions(-)
>
I tried your patchsets.
linux-3.18.3 + Shit_A:
Build OK.
I tried to reproduce the problem that Ishimatsu had reported, but it
doesn't occur.
It seems that your patch fixes this problem.
linux-3.18.3 + Shit_B:
Build OK, but I encountered kernel panic at boot time.
[ 0.189000] BUG: unable to handle kernel NULL pointer dereference at
0000000000000008
[ 0.189000] IP: [<ffffffff8131ef96>] __list_add+0x16/0xc0
[ 0.189000] PGD 0
[ 0.189000] Oops: 0000 [#1] SMP
[ 0.189000] Modules linked in:
[ 0.189000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.18.3+ #3
[ 0.189000] Hardware name: FUJITSU PRIMEQUEST2800E/SB, BIOS PRIMEQUEST 2000
Series BIOS Version 01.81 12/03/2014
[ 0.189000] task: ffff880869678000 ti: ffff880869664000 task.ti:
ffff880869664000
[ 0.189000] RIP: 0010:[<ffffffff8131ef96>] [<ffffffff8131ef96>]
__list_add+0x16/0xc0
[ 0.189000] RSP: 0000:ffff880869667be8 EFLAGS: 00010296
[ 0.189000] RAX: ffff88087f83cda8 RBX: ffff88087f83cd80 RCX: 0000000000000000
[ 0.189000] RDX: 0000000000000000 RSI: ffff88086912bb98 RDI: ffff88087f83cd80
[ 0.189000] RBP: ffff880869667c08 R08: 0000000000000000 R09: ffff88087f807480
[ 0.189000] R10: ffffffff810911b6 R11: ffffffff810956ac R12: 0000000000000000
[ 0.189000] R13: ffff88086912bb98 R14: 0000000000000400 R15: 0000000000000400
[ 0.189000] FS: 0000000000000000(0000) GS:ffff88087fc00000(0000)
knlGS:0000000000000000
[ 0.189000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.189000] CR2: 0000000000000008 CR3: 0000000001998000 CR4: 00000000001407f0
[ 0.189000] Stack:
[ 0.189000] 000000000000000a ffff88086912b800 ffff88087f83cd00
ffff88087f80c000
[ 0.189000] ffff880869667c48 ffffffff810912c8 ffff880869667c28
ffff88087f803f00
[ 0.189000] 00000000fffffff4 ffff88086964b760 ffff88086964b6a0
ffff88086964b740
[ 0.189000] Call Trace:
[ 0.189000] [<ffffffff810912c8>] alloc_unbound_pwq+0x298/0x3b0
[ 0.189000] [<ffffffff81091ce8>] apply_workqueue_attrs+0x158/0x4c0
[ 0.189000] [<ffffffff81092424>] __alloc_workqueue_key+0x174/0x5b0
[ 0.189000] [<ffffffff813052a6>] ? alloc_cpumask_var_node+0x56/0x80
[ 0.189000] [<ffffffff81b21573>] init_workqueues+0x33d/0x40f
[ 0.189000] [<ffffffff81b21236>] ?
ftrace_define_fields_workqueue_execute_start+0x6a/0x6a
[ 0.189000] [<ffffffff81002144>] do_one_initcall+0xd4/0x210
[ 0.189000] [<ffffffff81b12f4d>] ? native_smp_prepare_cpus+0x34d/0x352
[ 0.189000] [<ffffffff81b0026d>] kernel_init_freeable+0xf5/0x23c
[ 0.189000] [<ffffffff81653370>] ? rest_init+0x80/0x80
[ 0.189000] [<ffffffff8165337e>] kernel_init+0xe/0xf0
[ 0.189000] [<ffffffff8166bcfc>] ret_from_fork+0x7c/0xb0
[ 0.189000] [<ffffffff81653370>] ? rest_init+0x80/0x80
[ 0.189000] Code: ff b8 f4 ff ff ff e9 3b ff ff ff b8 f4 ff ff ff e9 31 ff
ff ff 55 48 89 e5 41 55 49 89 f5 41 54 49 89 d4 53 48 89 fb 48 83 ec 08 <4c> 8b
42 08 49 39 f0 75 2e 4d 8b 45 00 4d 39 c4 75 6c 4c 39 e3
[ 0.189000] RIP [<ffffffff8131ef96>] __list_add+0x16/0xc0
[ 0.189000] RSP <ffff880869667be8>
[ 0.189000] CR2: 0000000000000008
[ 0.189000] ---[ end trace 58feee6875cf67cf ]---
[ 0.189000] Kernel panic - not syncing: Fatal exception
[ 0.189000] ---[ end Kernel panic - not syncing: Fatal exception
Sincerely,
Taku Izumi
> Both patch1 of the both solutions are: reset pool->node and unhash the pool,
> it is suggested by TJ, I found it is a good leading-step for fixing the bug.
>
> The other patches are handling wq_numa_possible_cpumask where the solutions
> diverge.
>
> Solution_A uses present_mask rather than possible_cpumask. It adds
> wq_numa_notify_cpu_present_set/cleared() for notifications of
> the changes of cpu_present_mask. But the notifications are un-existed
> right now, so I fake one (wq_numa_check_present_cpumask_changes())
> to imitate them. I hope the memory people add a real one.
>
> Solution_B uses online_mask rather than possible_cpumask.
> this solution remove more coupling between numa_code and workqueue,
> it just depends on cpumask_of_node(node).
>
> Patch2_of_Solution_B removes the wq_numa_possible_cpumask and add
> overhead when cpu hot[un]plug, Patch3 reduce this overhead.
>
> Thanks,
> Lai
>
>
> Reported-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
> Cc: Tejun Heo <t...@kernel.org>
> Cc: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
> Cc: "Gu, Zheng" <guz.f...@cn.fujitsu.com>
> Cc: tangchen <tangc...@cn.fujitsu.com>
> Cc: Hiroyuki KAMEZAWA <kamezawa.hir...@jp.fujitsu.com>
> --
> 2.1.0
>
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