Re: [PATCH v4 09/10] workqueue: Implement system-wide nr_active enforcement for unbound workqueues

[Nathan Chancellor]

On Tue, Jan 30, 2024 at 06:13:02PM -1000, Tejun Heo wrote:
> On Tue, Jan 30, 2024 at 09:12:05PM -0700, Nathan Chancellor wrote:
> > Hi Tejun,
> > 
> > On Tue, Jan 30, 2024 at 06:02:52PM -1000, Tejun Heo wrote:
> > > Hello,
> > > 
> > > Thanks for the report. Can you please test whether the following patch fixes
> > > the problem?
> > 
> > I just tested this change on top of 5797b1c18919 but it does not appear
> > to resolve the issue for any of the three configurations that I tested.
> 
> Bummer. Can you map the faulting address to the source line?

Sure, here is the arm64 stacktrace run through
scripts/decode_stacktrace.sh, the line numbers correspond to your tree
at 5797b1c18919.

[    0.000000] Unable to handle kernel paging request at virtual address ffff000021c0b380
[    0.000000] Mem abort info:
[    0.000000]   ESR = 0x0000000096000006
[    0.000000]   EC = 0x25: DABT (current EL), IL = 32 bits
[    0.000000]   SET = 0, FnV = 0
[    0.000000]   EA = 0, S1PTW = 0
[    0.000000]   FSC = 0x06: level 2 translation fault
[    0.000000] Data abort info:
[    0.000000]   ISV = 0, ISS = 0x00000006, ISS2 = 0x00000000
[    0.000000]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[    0.000000]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[    0.000000] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000413b1000
[    0.000000] [ffff000021c0b380] pgd=180000005fff7003, p4d=180000005fff7003, pud=180000005fff6003, pmd=0000000000000000
[    0.000000] Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.7.0-09946-g5797b1c18919 #1
[    0.000000] Hardware name: linux,dummy-virt (DT)
[    0.000000] pstate: 600000c9 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    0.000000] pc : wq_update_node_max_active (include/asm-generic/bitops/generic-non-atomic.h:128 include/linux/cpumask.h:504 kernel/workqueue.c:1513)
[    0.000000] lr : apply_wqattrs_commit (kernel/workqueue.c:4838)
[    0.000000] sp : ffff8000814b3be0
[    0.000000] x29: ffff8000814b3be0 x28: ffff000001c0d600 x27: 0000000000000000
[    0.000000] x26: ffff000001c0d6c0 x25: 0000000000000001 x24: 0000000000000200
[    0.000000] x23: 00000000ffffffff x22: ffff8000814b9c40 x21: 0000000000000008
[    0.000000] x20: ffff8000814b9a40 x19: ffff000001c0b360 x18: ffff00001feebed0
[    0.000000] x17: 0000000000c65c70 x16: ffff00001feebb28 x15: fffffc0000070488
[    0.000000] x14: 0000000000000000 x13: 0000000000000000 x12: ffff00001feebb28
[    0.000000] x11: 0000000000000001 x10: ffff000001c0b388 x9 : 0000000000000000
[    0.000000] x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffff000001c0d600
[    0.000000] x5 : ffff000001c0d600 x4 : ffff000001c0e880 x3 : ffff000001c0d600
[    0.000000] x2 : ffff000001c0b388 x1 : ffff8000814b9000 x0 : 0000000003ffffff
[    0.000000] Call trace:
[    0.000000] wq_update_node_max_active (include/asm-generic/bitops/generic-non-atomic.h:128 include/linux/cpumask.h:504 kernel/workqueue.c:1513)
[    0.000000] apply_wqattrs_commit (kernel/workqueue.c:4838)
[    0.000000] apply_workqueue_attrs_locked (kernel/workqueue.c:4745 kernel/workqueue.c:4864)
[    0.000000] alloc_workqueue (kernel/workqueue.c:4894 kernel/workqueue.c:5015 kernel/workqueue.c:5224)
[    0.000000] workqueue_init_early (kernel/workqueue.c:7210)
[    0.000000] start_kernel (init/main.c:965)
[    0.000000] __primary_switched (arch/arm64/kernel/head.S:524)
[ 0.000000] Code: f9418033 d000a081 9100a262 f90037e2 (f8607840)
All code
========
   0:*  33 80 41 f9 81 a0       xor    -0x5f7e06bf(%rax),%eax           <-- trapping instruction
   6:   00 d0                   add    %dl,%al
   8:   62 a2 00 91 e2          (bad)
   d:   37                      (bad)
   e:   00 f9                   add    %bh,%cl
  10:   40 78 60                rex js 0x73
  13:   f8                      clc

Code starting with the faulting instruction
===========================================
   0:   40 78 60                rex js 0x63
   3:   f8                      clc
[    0.000000] ---[ end trace 0000000000000000 ]---
[    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[    0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---

Cheers,
Nathan