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BUG: KCSAN: data-race in run_timer_softirq / try_to_del_timer_sync

write to 0xffff88812c11dc88 of 8 bytes by interrupt on cpu 1:
 expire_timers kernel/time/timer.c:1451 [inline]
 __run_timers kernel/time/timer.c:1774 [inline]
 __run_timers kernel/time/timer.c:1741 [inline]
 run_timer_softirq+0xb1c/0xbd0 kernel/time/timer.c:1787
 __do_softirq+0x118/0x34a kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xb5/0xd0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 smp_apic_timer_interrupt+0xe2/0x270 arch/x86/kernel/apic/apic.c:1140
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 constant_test_bit+0x20/0x30 arch/x86/include/asm/bitops.h:211
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:111 [inline]
 set_buffer_meta include/linux/buffer_head.h:134 [inline]
 __ext4_handle_dirty_metadata+0x3b/0x3d0 fs/ext4/ext4_jbd2.c:303
 ext4_mb_mark_diskspace_used+0x5c7/0xa60 fs/ext4/mballoc.c:3052
 ext4_mb_new_blocks+0x714/0x1e20 fs/ext4/mballoc.c:4585
 ext4_ext_map_blocks+0x18cb/0x1fb0 fs/ext4/extents.c:4218
 ext4_map_blocks+0x230/0xcf0 fs/ext4/inode.c:621
 _ext4_get_block+0x131/0x2b0 fs/ext4/inode.c:772
 ext4_get_block+0x3e/0x50 fs/ext4/inode.c:789
 ext4_block_write_begin+0x336/0xbd0 fs/ext4/inode.c:1053
 ext4_write_begin+0x3a4/0xb20 fs/ext4/inode.c:1178
 ext4_da_write_begin+0x438/0xa10 fs/ext4/inode.c:2940
 pagecache_write_begin+0x67/0x90 mm/filemap.c:3121
 __page_symlink+0x127/0x190 fs/namei.c:4642
 ext4_symlink+0x4a5/0x9e0 fs/ext4/namei.c:3333
 vfs_symlink fs/namei.c:3937 [inline]
 vfs_symlink+0x216/0x330 fs/namei.c:3923
 do_symlinkat+0x1ac/0x1e0 fs/namei.c:3964
 __do_sys_symlinkat fs/namei.c:3978 [inline]
 __se_sys_symlinkat fs/namei.c:3975 [inline]
 __x64_sys_symlinkat+0x49/0x60 fs/namei.c:3975
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812c11dc88 of 8 bytes by task 10 on cpu 0:
 try_to_del_timer_sync+0x40/0xb0 kernel/time/timer.c:1226
 del_timer_sync+0x68/0xa0 kernel/time/timer.c:1366
 schedule_timeout+0x106/0x280 kernel/time/timer.c:1899
 rcu_gp_fqs_loop+0x34c/0x540 kernel/rcu/tree.c:1674
 rcu_gp_kthread+0x113/0x1e0 kernel/rcu/tree.c:1836
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10 Comm: rcu_preempt Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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