[syzbot] riscv/fixes boot error: INFO: rcu detected stall in corrupted

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    950b879b7f02 riscv: Fixup race condition on PG_dcache_clea..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes
console output: https://syzkaller.appspot.com/x/log.txt?x=137aaec0c80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b3cd714c8e9a6e01
dashboard link: https://syzkaller.appspot.com/bug?extid=42670398d6ddb118138f
compiler:       riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: riscv64

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+42670398d6ddb118138f at syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...0: (1 GPs behind) idle=36ec/1/0x4000000000000000 softirq=6589/6590 fqs=9960
	(detected by 1, t=30504 jiffies, g=14713, q=4 ncpus=2)
Task dump for CPU 0:
task:cmp             state:R  running task     stack:0     pid:2746  ppid:2744   flags:0x00000008
Call Trace:
[<ffffffff834348b8>] context_switch kernel/sched/core.c:5244 [inline]
[<ffffffff834348b8>] __schedule+0x624/0x1254 kernel/sched/core.c:6555
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...0: (1 GPs behind) idle=36ec/1/0x4000000000000000 softirq=6589/6590 fqs=28261
	(detected by 1, t=122009 jiffies, g=14713, q=4 ncpus=2)
Task dump for CPU 0:
task:cmp             state:R  running task     stack:0     pid:2746  ppid:2744   flags:0x00000008
Call Trace:
[<ffffffff834348b8>] context_switch kernel/sched/core.c:5244 [inline]
[<ffffffff834348b8>] __schedule+0x624/0x1254 kernel/sched/core.c:6555


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