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BUG: KCSAN: data-race in enqueue_timer / wbt_wait

write to 0xffff88812aa6fc18 of 8 bytes by interrupt on cpu 1:
 hlist_add_head include/linux/list.h:787 [inline]
 enqueue_timer+0x6c/0x210 kernel/time/timer.c:540
 __internal_add_timer+0x4f/0x60 kernel/time/timer.c:553
 internal_add_timer kernel/time/timer.c:595 [inline]
 __mod_timer kernel/time/timer.c:1053 [inline]
 mod_timer+0x303/0x7a0 kernel/time/timer.c:1100
 garp_join_timer_arm+0x65/0x80 net/802/garp.c:398
 garp_join_timer+0x7c/0x90 net/802/garp.c:411
 call_timer_fn+0x5f/0x2f0 kernel/time/timer.c:1404
 expire_timers kernel/time/timer.c:1449 [inline]
 __run_timers kernel/time/timer.c:1773 [inline]
 __run_timers kernel/time/timer.c:1740 [inline]
 run_timer_softirq+0xc0c/0xcd0 kernel/time/timer.c:1786
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 arch_local_irq_enable arch/x86/include/asm/paravirt.h:762 [inline]
 lookup_bh_lru fs/buffer.c:1320 [inline]
 __find_get_block+0x217/0x760 fs/buffer.c:1332
 __getblk_gfp+0x50/0x570 fs/buffer.c:1358
 sb_getblk include/linux/buffer_head.h:325 [inline]
 __ext4_get_inode_loc+0x228/0x960 fs/ext4/inode.c:4240
 ext4_get_inode_loc+0x3f/0x50 fs/ext4/inode.c:4355
 ext4_reserve_inode_write+0x7f/0x150 fs/ext4/inode.c:5566
 ext4_mark_inode_dirty+0x7f/0x420 fs/ext4/inode.c:5732
 __ext4_ext_dirty+0xfc/0x120 fs/ext4/extents.c:177
 ext4_swap_extents+0xcd9/0xe10 fs/ext4/extents.c:5964
 move_extent_per_page fs/ext4/move_extent.c:339 [inline]
 ext4_move_extents+0x1244/0x1e40 fs/ext4/move_extent.c:673
 ext4_ioctl+0x2b73/0x3290 fs/ext4/ioctl.c:992
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:545 [inline]
 do_vfs_ioctl+0x84f/0xcf0 fs/ioctl.c:732
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:749
 __do_sys_ioctl fs/ioctl.c:756 [inline]
 __se_sys_ioctl fs/ioctl.c:754 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:754
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812aa6fc18 of 8 bytes by task 4365 on cpu 0:
 blk_stat_is_active block/blk-stat.h:131 [inline]
 wbt_wait+0x177/0x250 block/blk-wbt.c:593
 __rq_qos_throttle+0x47/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_make_request+0x29c/0xf60 block/blk-mq.c:1932
 generic_make_request block/blk-core.c:1066 [inline]
 generic_make_request+0x196/0x700 block/blk-core.c:1008
 submit_bio+0x96/0x3c0 block/blk-core.c:1192
 submit_bh_wbc+0x40f/0x460 fs/buffer.c:3135
 submit_bh fs/buffer.c:3141 [inline]
 __sync_dirty_buffer+0xd3/0x210 fs/buffer.c:3227
 sync_dirty_buffer+0x24/0x40 fs/buffer.c:3240
 __fat_write_inode+0x4c7/0x520 fs/fat/inode.c:892
 fat_write_inode+0x6d/0xf0 fs/fat/inode.c:908
 write_inode fs/fs-writeback.c:1312 [inline]
 __writeback_single_inode+0x6f7/0x8e0 fs/fs-writeback.c:1511
 writeback_single_inode+0x232/0x310 fs/fs-writeback.c:1565
 sync_inode fs/fs-writeback.c:2602 [inline]
 sync_inode_metadata+0x74/0xa0 fs/fs-writeback.c:2622
 __generic_file_fsync+0x122/0x190 fs/libfs.c:1011
 fat_file_fsync+0x58/0x120 fs/fat/file.c:190
 vfs_fsync_range+0x82/0x150 fs/sync.c:197
 generic_write_sync include/linux/fs.h:2856 [inline]
 generic_file_write_iter+0x318/0x38c mm/filemap.c:3474
 call_write_iter include/linux/fs.h:1902 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983
 iter_file_splice_write+0x530/0x840 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0xa0/0xc0 fs/splice.c:1037
 splice_direct_to_actor+0x22b/0x540 fs/splice.c:992
 do_splice_direct+0x161/0x1e0 fs/splice.c:1080
 do_sendfile+0x384/0x7f0 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1519 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0xbe/0x140 fs/read_write.c:1511
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4365 Comm: syz-executor.3 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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