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BUG: KCSAN: data-race in expire_timers / try_to_del_timer_sync

write to 0xffff888237c376c8 of 8 bytes by interrupt on cpu 0:
 expire_timers+0x13d/0x250 kernel/time/timer.c:1465
 __run_timers+0x358/0x420 kernel/time/timer.c:1732
 run_timer_softirq+0x19/0x30 kernel/time/timer.c:1745
 __do_softirq+0x12c/0x26e kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x9a/0xb0 kernel/softirq.c:636
 sysvec_apic_timer_interrupt+0x69/0x80 arch/x86/kernel/apic/apic.c:1100
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
 get_ctx kernel/kcsan/core.c:202 [inline]
 check_access kernel/kcsan/core.c:640 [inline]
 __tsan_read4+0x117/0x180 kernel/kcsan/core.c:863
 perf_callchain_store include/linux/perf_event.h:1283 [inline]
 perf_callchain_kernel+0x27d/0x380 arch/x86/events/core.c:2782
 get_perf_callchain+0x3dd/0x430 kernel/events/callchain.c:200
 perf_callchain kernel/events/core.c:7252 [inline]
 perf_prepare_sample+0x27e/0x1080 kernel/events/core.c:7279
 __perf_event_output kernel/events/core.c:7448 [inline]
 perf_event_output_forward+0x36/0xb0 kernel/events/core.c:7468
 __perf_event_overflow+0x136/0x1e0 kernel/events/core.c:9140
 perf_swevent_event+0x1f9/0x3c0 kernel/events/core.c:9216
 do_perf_sw_event kernel/events/core.c:9357 [inline]
 ___perf_sw_event+0x24f/0x2d0 kernel/events/core.c:9388
 __perf_sw_event+0xe7/0x120 kernel/events/core.c:9400
 mm_account_fault include/linux/perf_event.h:1170 [inline]
 handle_mm_fault+0x74c/0x1a50 mm/memory.c:4805
 do_user_addr_fault+0x609/0xbe0 arch/x86/mm/fault.c:1390
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x91/0x220 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568
 __get_user_nocheck_1+0x6/0x10 arch/x86/lib/getuser.S:103
 fault_in_pages_readable include/linux/pagemap.h:786 [inline]
 iov_iter_fault_in_readable+0x1bd/0x290 lib/iov_iter.c:453
 generic_perform_write+0xc3/0x3c0 mm/filemap.c:3646
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c376c8 of 8 bytes by task 11 on cpu 1:
 try_to_del_timer_sync+0xe3/0x290 kernel/time/timer.c:1233
 del_timer_sync kernel/time/timer.c:1380 [inline]
 schedule_timeout+0x108/0x240 kernel/time/timer.c:1880
 rcu_gp_fqs_loop kernel/rcu/tree.c:1996 [inline]
 rcu_gp_kthread+0xbf7/0xec0 kernel/rcu/tree.c:2169
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

value changed: 0xffffc90000277e60 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11 Comm: rcu_sched Tainted: G        W         5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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