WARNING: suspicious RCU usage in unmap_page

WARNING: suspicious RCU usage in unmap_page_range
Status: upstream: reported on 2020/11/15 19:30
Reported-by: syzbot+4ca458af025542e76123@syzkaller.appspotmail.com
First crash: 160d, last: 19d

Sample crash report:

=============================
WARNING: suspicious RCU usage
5.12.0-rc5-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8294 Illegal context switch in RCU-sched read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
no locks held by syz-executor.1/21701.

stack backtrace:
CPU: 0 PID: 21701 Comm: syz-executor.1 Not tainted 5.12.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep+0x266/0x2c0 kernel/sched/core.c:8294
 zap_pte_range mm/memory.c:1340 [inline]
 zap_pmd_range mm/memory.c:1374 [inline]
 zap_pud_range mm/memory.c:1403 [inline]
 zap_p4d_range mm/memory.c:1424 [inline]
 unmap_page_range+0xfd2/0x2650 mm/memory.c:1445
 unmap_single_vma+0x198/0x300 mm/memory.c:1490
 unmap_vmas+0x16d/0x2f0 mm/memory.c:1522
 exit_mmap+0x2a8/0x590 mm/mmap.c:3218
 __mmput+0x122/0x470 kernel/fork.c:1090
 mmput+0x58/0x60 kernel/fork.c:1111
 exit_mm kernel/exit.c:501 [inline]
 do_exit+0xb0a/0x2a60 kernel/exit.c:812
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x47f/0x2150 kernel/signal.c:2781
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: Unable to access opcode bytes at RIP 0x46642f.
RSP: 002b:00007f54283de188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: 0000000000000000 RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000020000040 RSI: 000000004030582a RDI: 0000000000000004
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffeff469d2f R14: 00007f54283de300 R15: 0000000000022000

Crashes (5):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Title
ci-upstream-kasan-gce-selinux-root	2021/04/02 01:55	upstream	ffd9fb54	6a81331a	.config	log	report	info	WARNING: suspicious RCU usage in unmap_page_range
ci-upstream-kasan-gce-root	2021/03/31 17:30	upstream	5e46d1b7	6a81331a	.config	log	report	info	WARNING: suspicious RCU usage in unmap_page_range
ci-upstream-kasan-gce-selinux-root	2021/03/31 05:30	upstream	2bb25b3a	6a81331a	.config	log	report	info	WARNING: suspicious RCU usage in unmap_page_range
ci-qemu-upstream	2021/01/02 09:15	upstream	f6e1ea19	79264ae3	.config	log	report	info
ci-qemu-upstream	2020/11/11 19:25	upstream	eccc8767	cca87986	.config	log	report	info