KCSAN: data-race in __mod_timer / expire_timers

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 35e884f8 Merge tag 'for-linus-5.8b-rc4-tag' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=156c0a5b100000
kernel config: https://syzkaller.appspot.com/x/.config?x=ef2c2e4f6006998c
dashboard link: https://syzkaller.appspot.com/bug?extid=aa7c2385d46c5eba0b89
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project.git ca2dcbd030eadbf0aa9b660efe864ff08af6e18b)
CC: [ak...@linux-foundation.org b...@alien8.de hkall...@gmail.com h...@zytor.com linux-...@vger.kernel.org lu...@kernel.org mi...@redhat.com tg...@linutronix.de x...@kernel.org]

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+aa7c23...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __mod_timer / expire_timers

write to 0xffff88812c11cb08 of 8 bytes by interrupt on cpu 1:
expire_timers+0x11e/0x290 kernel/time/timer.c:1450
__run_timers+0x443/0x500 kernel/time/timer.c:1773
run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1786
__do_softirq+0x198/0x360 kernel/softirq.c:292
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
do_softirq_own_stack+0x5d/0x80 arch/x86/kernel/irq_64.c:77
invoke_softirq kernel/softirq.c:387 [inline]
__irq_exit_rcu+0x115/0x120 kernel/softirq.c:417
sysvec_apic_timer_interrupt+0xba/0xd0 arch/x86/kernel/apic/apic.c:1091
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
kcsan_setup_watchpoint+0x47c/0x4d0 kernel/kcsan/core.c:542
rcu_preempt_read_enter kernel/rcu/tree_plugin.h:354 [inline]
__rcu_read_lock+0x21/0x40 kernel/rcu/tree_plugin.h:374
rcu_read_lock include/linux/rcupdate.h:632 [inline]
lock_page_memcg+0x2c/0xf0 mm/memcontrol.c:1977
page_remove_rmap+0x1d/0x2e0 mm/rmap.c:1328
zap_pte_range+0x702/0x1610 mm/memory.c:1089
zap_pmd_range mm/memory.c:1193 [inline]
zap_pud_range mm/memory.c:1222 [inline]
zap_p4d_range mm/memory.c:1243 [inline]
unmap_page_range+0x751/0x870 mm/memory.c:1264
unmap_single_vma+0x157/0x210 mm/memory.c:1309
unmap_vmas+0xc0/0x150 mm/memory.c:1341
exit_mmap+0x1c7/0x3b0 mm/mmap.c:3150
__mmput+0xa2/0x220 kernel/fork.c:1093
mmput+0x38/0x40 kernel/fork.c:1114
exit_mm+0x2c8/0x330 kernel/exit.c:482
do_exit+0x415/0x16e0 kernel/exit.c:792
do_group_exit+0xa8/0x180 kernel/exit.c:903
__do_sys_exit_group+0xb/0x10 kernel/exit.c:914
__se_sys_exit_group+0x5/0x10 kernel/exit.c:912
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:912
do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812c11cb08 of 8 bytes by task 26 on cpu 0:
__mod_timer+0x399/0xf00 kernel/time/timer.c:1026
add_timer+0x38/0x50 kernel/time/timer.c:1136
__queue_delayed_work+0xea/0x150 kernel/workqueue.c:1649
queue_delayed_work_on+0x8d/0xe0 kernel/workqueue.c:1674
queue_delayed_work include/linux/workqueue.h:522 [inline]
bond_loadbalance_arp_mon drivers/net/bonding/bond_main.c:2801 [inline]
bond_arp_monitor+0xbb7/0x2480 drivers/net/bonding/bond_main.c:3100
process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
kthread+0x20d/0x230 kernel/kthread.c:291
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26 Comm: kworker/u4:2 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bond4 bond_arp_monitor
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.