rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=12162 jiffies, g=39753, q=1404 ncpus=1)
rcu: All QSes seen, last rcu_preempt kthread activity 9911 (4294967364-4294957453), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 9911 jiffies! g39753 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27560 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 5781 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__list_del_entry_valid include/linux/list.h:124 [inline]
RIP: 0010:__list_del_entry include/linux/list.h:215 [inline]
RIP: 0010:list_del_init include/linux/list.h:287 [inline]
RIP: 0010:remove_zspage mm/zsmalloc.c:773 [inline]
RIP: 0010:fix_fullness_group+0x15b/0x500 mm/zsmalloc.c:794
Code: 4c 03 34 24 4c 89 f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 05 ef f5 ff 49 8b 06 4c 39 f0 0f 84 90 03 00 00 4c 8d 63 18 <4c> 89 e7 e8 dd 1f a3 02 84 c0 0f 84 91 00 00 00 e8 f0 fe 90 ff 4c
RSP: 0018:ffffc90002cef3a0 EFLAGS: 00000202
RAX: ffff888058b79638 RBX: ffff8880523380e0 RCX: ffff888033702440
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 000000000000000d
RBP: 0000000000000007 R08: ffff888033612873 R09: 1ffff110066c250e
R10: dffffc0000000000 R11: ffffed10066c250f R12: ffff8880523380f8
R13: 0000000000000009 R14: ffff88803f5e94d0 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff88808d20c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055cd71817b68 CR3: 0000000011578000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 zs_free+0x36c/0x510 mm/zsmalloc.c:1450
 zswap_entry_free+0x345/0x490 mm/zswap.c:808
 swap_range_free mm/swapfile.c:1134 [inline]
 swap_entries_free+0x295/0x750 mm/swapfile.c:1580
 swap_entry_put_locked mm/swapfile.c:1394 [inline]
 swap_entries_put_map+0x3a7/0x750 mm/swapfile.c:1513
 swap_entries_put_map_nr mm/swapfile.c:1537 [inline]
 free_swap_and_cache_nr+0x15d/0x3b0 mm/swapfile.c:1817
 zap_nonpresent_ptes mm/memory.c:1620 [inline]
 do_zap_pte_range mm/memory.c:1686 [inline]
 zap_pte_range mm/memory.c:1726 [inline]
 zap_pmd_range mm/memory.c:1818 [inline]
 zap_pud_range mm/memory.c:1847 [inline]
 zap_p4d_range mm/memory.c:1868 [inline]
 unmap_page_range+0x1a64/0x4370 mm/memory.c:1889
 unmap_single_vma mm/memory.c:1932 [inline]
 unmap_vmas+0x399/0x580 mm/memory.c:1976
 exit_mmap+0x248/0xb50 mm/mmap.c:1280
 __mmput+0x118/0x420 kernel/fork.c:1130
 exit_mm+0x1da/0x2c0 kernel/exit.c:582
 do_exit+0x648/0x2300 kernel/exit.c:949
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 __do_sys_exit_group kernel/exit.c:1113 [inline]
 __se_sys_exit_group kernel/exit.c:1111 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1111
 x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fee5c8f16c5
Code: Unable to access opcode bytes at 0x7fee5c8f169b.
RSP: 002b:00007ffe15b4d588 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000055cd71831600 RCX: 00007fee5c8f16c5
RDX: 00000000000000e7 RSI: fffffffffffffe68 RDI: 0000000000000000
RBP: 000055cd7180e910 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe15b4d5d0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>