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BUG: KCSAN: data-race in __percpu_ref_switch_mode / percpu_ref_switch_to_atomic_rcu

write to 0xffff8881245595d0 of 8 bytes by interrupt on cpu 0:
 percpu_ref_call_confirm_rcu lib/percpu-refcount.c:156 [inline]
 percpu_ref_switch_to_atomic_rcu+0x188/0x360 lib/percpu-refcount.c:205
 rcu_do_batch kernel/rcu/tree.c:2508 [inline]
 rcu_core+0xbd5/0xd90 kernel/rcu/tree.c:2743
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2756
 __do_softirq+0x12c/0x26e kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu kernel/softirq.c:636 [inline]
 irq_exit_rcu+0x4e/0xa0 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x69/0x80 arch/x86/kernel/apic/apic.c:1097
 asm_sysvec_apic_timer_interrupt+0x12/0x20
 kcsan_setup_watchpoint+0x94/0x3f0 kernel/kcsan/core.c:437
 crc32_body lib/crc32.c:111 [inline]
 crc32_le_generic lib/crc32.c:179 [inline]
 __crc32c_le_base+0xbf/0x350 lib/crc32.c:202
 chksum_update+0x2e/0x50 crypto/crc32c_generic.c:88
 crypto_shash_update+0x13c/0x1a0 crypto/shash.c:131
 ext4_chksum fs/ext4/ext4.h:2452 [inline]
 ext4_block_bitmap_csum_set+0x12b/0x250 fs/ext4/bitmap.c:94
 ext4_mb_mark_diskspace_used+0x78b/0xca0 fs/ext4/mballoc.c:3858
 ext4_mb_new_blocks+0xae3/0x1fc0 fs/ext4/mballoc.c:5604
 ext4_ext_map_blocks+0x15ed/0x1ff0 fs/ext4/extents.c:4250
 ext4_map_blocks+0x71e/0xf00 fs/ext4/inode.c:637
 ext4_getblk+0xc6/0x3e0 fs/ext4/inode.c:847
 ext4_bread+0x28/0x100 fs/ext4/inode.c:900
 ext4_append+0xd1/0x1c0 fs/ext4/namei.c:67
 ext4_init_new_dir+0x177/0x500 fs/ext4/namei.c:2893
 ext4_mkdir+0x329/0x760 fs/ext4/namei.c:2939
 vfs_mkdir+0x2c3/0x3e0 fs/namei.c:3885
 do_mkdirat+0x12e/0x2e0 fs/namei.c:3911
 __do_sys_mkdir fs/namei.c:3931 [inline]
 __se_sys_mkdir fs/namei.c:3929 [inline]
 __x64_sys_mkdir+0x40/0x50 fs/namei.c:3929
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881245595d0 of 8 bytes by task 27932 on cpu 1:
 __percpu_ref_switch_mode+0xf6/0x3c0 lib/percpu-refcount.c:275
 percpu_ref_resurrect+0xc2/0x110 lib/percpu-refcount.c:473
 io_refs_resurrect fs/io_uring.c:1198 [inline]
 io_ctx_quiesce fs/io_uring.c:10628 [inline]
 __io_uring_register fs/io_uring.c:10656 [inline]
 __do_sys_io_uring_register+0x124b/0x2110 fs/io_uring.c:10794
 __se_sys_io_uring_register fs/io_uring.c:10774 [inline]
 __x64_sys_io_uring_register+0x4f/0x60 fs/io_uring.c:10774
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffffffff818d41a0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27932 Comm: syz-executor.5 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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