> > > I did already let Greg know when he emailed us on backporting the
> > > patch to stable, and he acked saying he removed them. So as long as
> > > these are not in the queue for 5.6 (it is not in Linus' tree yet), we
> > > should be good.
> >
> > The reported bug is still noticed on Linux mainline master branch
> > The Kernel BUG noticed on x86_64 and i386 running selftest on Linux
> > mainline kernel 5.6.0.
>
> Oh sorry, I thought that this patch was dropped from the maintainer's
> for-next branch.
>
> Heikki, what do you think about my suggestion of having kobject
> deallocate its children?
>
> In the meantime, are people cool with the patch that Heikki proposed
> as a temporary mitigation? I think my solution might be a bit more
> involved. If I don't hear anything back, I will send out Heikki's
> suggestion as a patch.
This reported problem still noticed on 5.7.0-rc1
Test crash log:
-------------------
[ 281.822463] BUG: kernel NULL pointer dereference, address: 00000000
[ 281.829543] #PF: supervisor read access in kernel mode
[ 281.834680] #PF: error_code(0x0000) - not-present page
[ 281.839820] *pde = 00000000
[ 281.842706] Oops: 0000 [#1] SMP
[ 281.845852] CPU: 1 PID: 3998 Comm: modprobe Tainted: G W
5.7.0-rc1 #1
[ 281.853590] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS
2.0b 07/27/2017
[ 281.861063] EIP: ida_free+0x61/0x130
[ 281.864641] Code: 00 c7 45 e8 00 00 00 00 c7 45 ec 00 00 00 00 0f
88 c4 00 00 00 89 d3 e8 0d 8e 87 00 89 c7 8d 45 d8 e8 93 1e 01 00 a8
01 75 3f <0f> a3 30 72 72 8b 45 d8 89 fa e8 e0 8f 87 00 53 68 08 ab fd
de e8
[ 281.883395] EAX: 00000000 EBX: 00000000 ECX: e422d8c0 EDX: 00000000
[ 281.889672] ESI: 00000000 EDI: 00000246 EBP: e5d63cdc ESP: e5d63cb0
[ 281.895935] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010046
[ 281.902720] CR0: 80050033 CR2: 00000000 CR3: 1db85000 CR4: 003406d0
[ 281.908978] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[ 281.915243] DR6: fffe0ff0 DR7: 00000400
[ 281.919073] Call Trace:
[ 281.921521] software_node_release+0x21/0x80
[ 281.925792] kobject_put+0xa8/0x1c0
[ 281.929284] kobject_del+0x40/0x60
[ 281.932680] kobject_put+0x92/0x1c0
[ 281.936165] fwnode_remove_software_node+0x30/0x50
[ 281.940957] software_node_unregister_nodes+0x2b/0x50
[ 281.946002] test_printf_init+0xe00/0x1d29 [test_printf]
[ 281.951320] ? fs_reclaim_acquire.part.121+0x5/0x30
[ 281.956202] ? test_hashed+0x54/0x54 [test_printf]
[ 281.960985] ? test_hashed+0x54/0x54 [test_printf]
[ 281.965770] do_one_initcall+0x54/0x2e0
[ 281.969639] ? rcu_read_lock_sched_held+0x47/0x70
[ 281.974366] ? kmem_cache_alloc_trace+0x285/0x2b0
[ 281.979063] ? do_init_module+0x21/0x1f7
[ 281.982982] ? do_init_module+0x21/0x1f7
[ 281.986899] do_init_module+0x50/0x1f7
[ 281.990659] load_module+0x1e32/0x2540
[ 281.994410] __ia32_sys_finit_module+0x8f/0xe0
[ 281.998854] do_fast_syscall_32+0x7f/0x330
[ 282.002949] entry_SYSENTER_32+0xaa/0x102
[ 282.006952] EIP: 0xb7f07ce1
[ 282.009742] Code: 5e 5d c3 8d b6 00 00 00 00 b8 40 42 0f 00 eb c1
8b 04 24 c3 8b 1c 24 c3 8b 34 24 c3 8b 3c 24 c3 90 51 52 55 89 e5 0f
34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d 76 00 58 b8 77 00 00 00 cd 80 90
8d 76
[ 282.028480] EAX: ffffffda EBX: 00000005 ECX: 0806233a EDX: 00000000
[ 282.034739] ESI: 099fe840 EDI: 099fe570 EBP: 099fe700 ESP: bf97146c
[ 282.040994] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000292
[ 282.047776] Modules linked in: test_printf(+) cls_bpf sch_fq 8021q
sch_ingress veth algif_hash x86_pkg_temp_thermal fuse [last unloaded:
gpio_mockup]
[ 282.061155] CR2: 0000000000000000
[ 282.064472] ---[ end trace 09f43fd7981266c9 ]---
[ 282.069084] EIP: ida_free+0x61/0x130
https://lkft.validation.linaro.org/scheduler/job/1362555#L7962
- Naresh
