supervisor write access in kernel mode in __pv_queued_spin_unlock_slowpath

[Hyeonggon Yoo]

On Sun, Jan 01, 2023 at 03:50:28PM +0900, Hyeonggon Yoo wrote:
> On Sat, Dec 31, 2022 at 11:26:25PM +0800, kernel test robot wrote:
> > 
> > Greeting,
> > 
> > FYI, we noticed kernel_BUG_at_include/linux/mm.h due to commit (built with gcc-11):
> > 
> > commit: 0af8489b0216fa1dd83e264bef8063f2632633d7 ("mm, slub: remove percpu slabs with CONFIG_SLUB_TINY")
> > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > 
> > [test failed on linux-next/master c76083fac3bae1a87ae3d005b5cb1cbc761e31d5]
> > 
> > in testcase: rcutorture
> > version: 
> > with following parameters:
> > 
> > 	runtime: 300s
> > 	test: default
> > 	torture_type: tasks-tracing
> > 
> > test-description: rcutorture is rcutorture kernel module load/unload test.
> > test-url: https://www.kernel.org/doc/Documentation/RCU/torture.txt
> > 
> > 
> > on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
> > 
> > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> > 
> > 
> > If you fix the issue, kindly add following tag
> > | Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
> > | Link: https://lore.kernel.org/oe-lkp/202212312021.bc1efe86-oliver.sang@xxxxxxxxx
> > 
> > 
> 
> <snip>
> 
> > 
> > 
> > To reproduce:
> > 
> >         # build kernel
> > 	cd linux
> > 	cp config-6.1.0-rc2-00014-g0af8489b0216 .config
> > 	make HOSTCC=gcc-11 CC=gcc-11 ARCH=i386 olddefconfig prepare modules_prepare bzImage modules
> > 	make HOSTCC=gcc-11 CC=gcc-11 ARCH=i386 INSTALL_MOD_PATH=<mod-install-dir> modules_install
> > 	cd <mod-install-dir>
> > 	find lib/ | cpio -o -H newc --quiet | gzip > modules.cgz
> > 
> > 
> >         git clone https://github.com/intel/lkp-tests.git
> >         cd lkp-tests
> >         bin/lkp qemu -k <bzImage> -m modules.cgz job-script # job-script is attached in this email
> > 
> >         # if come across any failure that blocks the test,
> >         # please remove ~/.lkp and /lkp dir to run from a clean state.
> 
> 
> I was unable to reproduce in the same way as described above
> because some files referenced in job-script couldn't be downloaded from
> download.01.org/0day :(
> 
> So I just built rcutorture module as builtin
> and I got weird spinlock bug on commit: 0af8489b0216
> ("mm, slub: remove percpu slabs with CONFIG_SLUB_TINY")

(+Cc KVM/Paravirt experts)

> full dmesg added as attachment
> 
> [ 1387.564837][   T57] BUG: unable to handle page fault for address: c108f5f4
> [ 1387.566649][   T57] #PF: supervisor write access in kernel mode
> [ 1387.567965][   T57] #PF: error_code(0x0003) - permissions violation
> [ 1387.569439][   T57] *pde = 010001e1 
> [ 1387.570276][   T57] Oops: 0003 [#1] SMP
> [ 1387.571149][   T57] CPU: 2 PID: 57 Comm: rcu_torture_rea Tainted: G S                 6.1.0-rc2-00010-g0af8489b0216 #2130 63d19ac2b985fca570c354d8750f489755de37ed
> [ 1387.574673][   T57] EIP: kvm_kick_cpu+0x54/0x90
> [ 1387.575802][   T57] Code: 2f c5 01 8b 04 9d e0 d4 4e c4 83 15 14 7b 2f c5 00 83 05 08 6d 2f c5 01 0f b7 0c 30 b8 05 00 00 00 83 15 0c 6d 2f c5 00 31 db <0f> 01 c1 83 05 10 6d 2f c5 01 8b 5d f8 8b 75 fc 83 15 14 6d 2f c5
> [ 1387.580456][   T57] EAX: 00000005 EBX: 00000000 ECX: 00000003 EDX: c108f5a0
> [ 1387.582071][   T57] ESI: c5153580 EDI: 00000046 EBP: c69cddf8 ESP: c69cddf0
> [ 1387.583775][   T57] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010046
> [ 1387.585643][   T57] CR0: 80050033 CR2: c108f5f4 CR3: 0776b000 CR4: 00350e90
> [ 1387.587492][   T57] Call Trace:
> [ 1387.588365][   T57]  __pv_queued_spin_unlock_slowpath+0x66/0x110
> [ 1387.589898][   T57]  __pv_queued_spin_unlock+0x4b/0x60
> [ 1387.591040][   T57]  __raw_callee_save___pv_queued_spin_unlock+0x9/0x10
> [ 1387.592771][   T57]  do_raw_spin_unlock+0x49/0xa0
> [ 1387.593805][   T57]  _raw_spin_unlock_irqrestore+0x53/0xd0
> [ 1387.594927][   T57]  swake_up_one+0x4f/0x70
> [ 1387.595739][   T57]  __rcu_report_exp_rnp+0x26b/0x470
> [ 1387.596730][   T57]  rcu_report_exp_cpu_mult+0x82/0x2f0
> [ 1387.597770][   T57]  rcu_qs+0xac/0x160
> [ 1387.598503][   T57]  rcu_note_context_switch+0x31/0x1e0
> [ 1387.599460][   T57]  __schedule+0xc5/0x770
> [ 1387.600195][   T57]  __cond_resched+0x7a/0x100
> [ 1387.600996][   T57]  stutter_wait+0x9e/0x2c0
> [ 1387.601956][   T57]  rcu_torture_reader+0x162/0x3e0
> [ 1387.603048][   T57]  ? rcu_torture_reader+0x3e0/0x3e0
> [ 1387.604269][   T57]  ? __kthread_parkme+0xab/0xf0
> [ 1387.605420][   T57]  kthread+0x167/0x1d0
> [ 1387.606383][   T57]  ? rcu_torture_read_exit_child+0xa0/0xa0
> [ 1387.607516][   T57]  ? kthread_exit+0x50/0x50
> [ 1387.608517][   T57]  ret_from_fork+0x19/0x24
> [ 1387.609548][   T57] Modules linked in:
> [ 1387.610187][   T57] CR2: 00000000c108f5f4
> [ 1387.610873][   T57] ---[ end trace 0000000000000000 ]---
> [ 1387.611829][   T57] EIP: kvm_kick_cpu+0x54/0x90
> [ 1387.612653][   T57] Code: 2f c5 01 8b 04 9d e0 d4 4e c4 83 15 14 7b 2f c5 00 83 05 08 6d 2f c5 01 0f b7 0c 30 b8 05 00 00 00 83 15 0c 6d 2f c5 00 31 db <0f> 01 c1 83 05 10 6d 2f c5 01 8b 5d f8 8b 75 fc 83 15 14 6d 2f c5
> [ 1387.616715][   T57] EAX: 00000005 EBX: 00000000 ECX: 00000003 EDX: c108f5a0
> [ 1387.618242][   T57] ESI: c5153580 EDI: 00000046 EBP: c69cddf8 ESP: c69cddf0
> [ 1387.619912][   T57] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010046
> [ 1387.621666][   T57] CR0: 80050033 CR2: c108f5f4 CR3: 0776b000 CR4: 00350e90
> [ 1387.623128][   T57] Kernel panic - not syncing: Fatal exception
> [ 1389.285045][   T57] Shutting down cpus with NMI
> [ 1389.297949][   T57] Kernel Offset: disabled
> [ 1389.299174][   T57] ---[ end Kernel panic - not syncing: Fatal exception ]---