BUG: sleeping function called from invalid context in vdso_join_timens

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    4d41ead6 Merge tag 'block-5.9-2020-08-28' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=174adf49900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=891ca5711a9f1650
dashboard link: https://syzkaller.appspot.com/bug?extid=49f84b6782afe2a2b20e
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+49f84b6782afe2a2b20e@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1491
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 479, name: syz-executor.3
INFO: lockdep is turned off.
irq event stamp: 845
hardirqs last  enabled at (845): [<ffffffff882cebdf>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
hardirqs last  enabled at (845): [<ffffffff882cebdf>] _raw_spin_unlock_irqrestore+0x6f/0xd0 kernel/locking/spinlock.c:191
hardirqs last disabled at (844): [<ffffffff882cea28>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (844): [<ffffffff882cea28>] _raw_spin_lock_irqsave+0x78/0xc0 kernel/locking/spinlock.c:159
softirqs last  enabled at (662): [<ffffffff88400f2f>] asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
softirqs last disabled at (653): [<ffffffff88400f2f>] asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:706
Preemption disabled at:
[<ffffffff882c3253>] preempt_schedule_irq+0x93/0x150 kernel/sched/core.c:4783
CPU: 1 PID: 479 Comm: syz-executor.3 Tainted: G      D           5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1f0/0x31e lib/dump_stack.c:118
 ___might_sleep+0x3c0/0x570 kernel/sched/core.c:7299
 down_read+0x17/0x50 kernel/locking/rwsem.c:1491
 mmap_read_lock include/linux/mmap_lock.h:46 [inline]
 vdso_join_timens+0x46/0x120 arch/x86/entry/vdso/vma.c:147
kernel tried to execute NX-protected page - exploit attempt? (uid: 0)
BUG: unable to handle page fault for address: ffff8880ae936310
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0011) - permissions violation
PGD c401067 P4D c401067 PUD 21ffff067 PMD 80000000ae8001e3 
Oops: 0011 [#2] PREEMPT SMP KASAN
CPU: 1 PID: 479 Comm: syz-executor.3 Tainted: G      D W         5.9.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011


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