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BUG: KCSAN: data-race in wb_timer_fn / wbt_wait

write to 0xffff888131e5cd04 of 4 bytes by interrupt on cpu 0:
 calc_wb_limits block/blk-wbt.c:304 [inline]
 scale_up block/blk-wbt.c:313 [inline]
 wb_timer_fn+0x403/0xa00 block/blk-wbt.c:382
 blk_stat_timer_fn+0x3f4/0x410 block/blk-stat.c:99
 call_timer_fn+0x2e/0x240 kernel/time/timer.c:1415
 expire_timers+0x116/0x260 kernel/time/timer.c:1460
 __run_timers+0x338/0x3d0 kernel/time/timer.c:1757
 run_timer_softirq+0x2e/0x60 kernel/time/timer.c:1770
 __do_softirq+0x198/0x331 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x5b/0x70 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:393 [inline]
 __irq_exit_rcu+0x115/0x120 kernel/softirq.c:423
 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:631
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline]
 kcsan_setup_watchpoint+0x4ee/0x550 kernel/kcsan/core.c:591
 tomoyo_path_matches_pattern+0x29/0x120 security/tomoyo/util.c:936
 tomoyo_compare_name_union security/tomoyo/file.c:87 [inline]
 tomoyo_check_path_acl+0x9b/0xe0 security/tomoyo/file.c:260
 tomoyo_check_acl+0xcc/0x200 security/tomoyo/domain.c:175
 tomoyo_path_permission security/tomoyo/file.c:586 [inline]
 tomoyo_path_perm+0x22f/0x330 security/tomoyo/file.c:838
 tomoyo_inode_getattr+0x18/0x20 security/tomoyo/tomoyo.c:123
 security_inode_getattr+0x7f/0xd0 security/security.c:1279
 vfs_getattr fs/stat.c:121 [inline]
 vfs_statx_fd fs/stat.c:151 [inline]
 vfs_fstat include/linux/fs.h:3126 [inline]
 __do_sys_newfstat fs/stat.c:398 [inline]
 __se_sys_newfstat+0x5a/0x510 fs/stat.c:395
 __x64_sys_newfstat+0x2d/0x40 fs/stat.c:395
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888131e5cd04 of 4 bytes by task 11414 on cpu 1:
 rwb_enabled block/blk-wbt.c:80 [inline]
 bio_to_wbt_flags block/blk-wbt.c:543 [inline]
 wbt_wait+0x36/0x2b0 block/blk-wbt.c:576
 __rq_qos_throttle+0x39/0x70 block/blk-rq-qos.c:72
 rq_qos_throttle block/blk-rq-qos.h:182 [inline]
 blk_mq_submit_bio+0x233/0x1020 block/blk-mq.c:2174
 __submit_bio_noacct_mq block/blk-core.c:1022 [inline]
 submit_bio_noacct+0x77d/0x930 block/blk-core.c:1055
 submit_bio+0x1f3/0x360 block/blk-core.c:1125
 submit_bh_wbc+0x38c/0x3d0 fs/buffer.c:3054
 submit_bh+0x21/0x30 fs/buffer.c:3060
 read_mmp_block+0x124/0x440 fs/ext4/mmp.c:91
 ext4_multi_mount_protect+0x3f2/0x670 fs/ext4/mmp.c:361
 ext4_fill_super+0x4667/0x7a30 fs/ext4/super.c:4548
 mount_bdev+0x1e2/0x280 fs/super.c:1419
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6325
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x190 fs/super.c:1549
 do_new_mount fs/namespace.c:2875 [inline]
 path_mount+0x1269/0x1c00 fs/namespace.c:3203
 do_mount fs/namespace.c:3216 [inline]
 __do_sys_mount fs/namespace.c:3424 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3401
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3401
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11414 Comm: syz-executor.0 Not tainted 5.9.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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