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: 68d, last: 17d

Sample crash report:

=============================
WARNING: suspicious RCU usage
5.11.0-rc1-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:7867 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.0/10153.

stack backtrace:
CPU: 2 PID: 10153 Comm: syz-executor.0 Not tainted 5.11.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ___might_sleep+0x266/0x2c0 kernel/sched/core.c:7867
 zap_pte_range mm/memory.c:1334 [inline]
 zap_pmd_range mm/memory.c:1368 [inline]
 zap_pud_range mm/memory.c:1397 [inline]
 zap_p4d_range mm/memory.c:1418 [inline]
 unmap_page_range+0xfd2/0x2640 mm/memory.c:1439
 unmap_single_vma+0x198/0x300 mm/memory.c:1484
 unmap_vmas+0x168/0x2e0 mm/memory.c:1516
 exit_mmap+0x2b1/0x5a0 mm/mmap.c:3220
 __mmput+0x122/0x470 kernel/fork.c:1083
 mmput+0x53/0x60 kernel/fork.c:1104
 exit_mm kernel/exit.c:500 [inline]
 do_exit+0xa97/0x29e0 kernel/exit.c:810
 do_group_exit+0x125/0x310 kernel/exit.c:920
 get_signal+0x3ec/0x2010 kernel/signal.c:2770
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811
 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:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45dd69
Code: Unable to access opcode bytes at RIP 0x45dd3f.
RSP: 002b:00007f3828781cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 000000000075bf68 RCX: 000000000045dd69
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 000000000075bf6c
RBP: 000000000075bf60 R08: 0000000000000016 R09: 0000000000000000
R10: ffffffffffffffff R11: 0000000000000246 R12: 000000000075bf6c
R13: 00007fff67e104ff R14: 00007f3828762000 R15: 0000000000000003

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-qemu-upstream	2021/01/02 09:15	upstream	f6e1ea19	79264ae3	.config	log	report			info	akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
ci-qemu-upstream	2020/11/11 19:25	upstream	eccc8767	cca87986	.config	log	report			info	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk