==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86ec1188 of 88 bytes by interrupt on cpu 1:
 prb_reserve+0x6fb/0xaf0 kernel/printk/printk_ringbuffer.c:1693
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x610 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __ext4_msg+0x1aa/0x1c0 fs/ext4/super.c:1001
 print_daily_error_info+0x7a/0x300 fs/ext4/super.c:3713
 call_timer_fn+0x36/0x250 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x40c/0x5f0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0x31/0x70 kernel/time/timer.c:2405
 handle_softirqs+0xcc/0x2a0 kernel/softirq.c:645
 __do_softirq kernel/softirq.c:679 [inline]
 invoke_softirq kernel/softirq.c:519 [inline]
 __irq_exit_rcu+0x44/0xe0 kernel/softirq.c:767
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1062
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
 console_flush_one_record arch/x86/include/asm/irqflags.h:-1 [inline]
 console_flush_all+0x528/0x6d0 kernel/printk/printk.c:3350
 __console_flush_and_unlock kernel/printk/printk.c:3380 [inline]
 console_unlock+0xa1/0x280 kernel/printk/printk.c:3420
 vprintk_emit+0x3e5/0x610 kernel/printk/printk.c:2479
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __quota_error+0x102/0x110 fs/quota/dquot.c:148
 write_blk+0xcc/0x100 fs/quota/quota_tree.c:73
 do_insert_tree+0x954/0xad0 fs/quota/quota_tree.c:407
 dq_insert_tree fs/quota/quota_tree.c:432 [inline]
 qtree_write_dquot+0x2b7/0x2e0 fs/quota/quota_tree.c:451
 v2_write_dquot+0xcb/0x130 fs/quota/quota_v2.c:372
 dquot_acquire+0x1bc/0x2b0 fs/quota/dquot.c:498
 ext4_acquire_dquot+0x15f/0x200 fs/ext4/super.c:7065
 dqget+0x51f/0x8b0 fs/quota/dquot.c:1002
 __dquot_initialize+0x28c/0x7c0 fs/quota/dquot.c:1462
 dquot_initialize+0x1a/0x30 fs/quota/dquot.c:1524
 ext4_process_orphan+0x2d/0x1c0 fs/ext4/orphan.c:328
 ext4_orphan_cleanup+0x753/0xab0 fs/ext4/orphan.c:473
 __ext4_fill_super fs/ext4/super.c:5726 [inline]
 ext4_fill_super+0x33ea/0x37b0 fs/ext4/super.c:5855
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1887
 get_tree_bdev+0x1f/0x30 fs/super.c:1910
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5887
 vfs_get_tree+0x57/0x1d0 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3848
 path_mount+0x4ad/0xb90 fs/namespace.c:4168
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4374
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4374
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86ec1188 of 8 bytes by task 6429 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2017 [inline]
 _prb_read_valid+0x325/0x930 kernel/printk/printk_ringbuffer.c:2174
 prb_first_valid_seq+0x35/0x70 kernel/printk/printk_ringbuffer.c:2302
 devkmsg_open+0x174/0x1b0 kernel/printk/printk.c:945
 memory_open+0xfa/0x120 drivers/char/mem.c:727
 chrdev_open+0x2eb/0x3a0 fs/char_dev.c:411
 do_dentry_open+0x49f/0xa60 fs/open.c:996
 vfs_open+0x37/0x1e0 fs/open.c:1101
 do_open fs/namei.c:4837 [inline]
 path_openat+0xc01/0x10d0 fs/namei.c:5000
 do_file_open+0x16c/0x290 fs/namei.c:5029
 do_sys_openat2+0xa0/0x130 fs/open.c:1417
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1434
 x64_sys_call+0x1f72/0x2550 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000002823 -> 0x0000000000004823

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6429 Comm: fido_id Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
fido_id[6429]: Failed to open report descriptor at '/sys/devices/virtual/misc/uhid/report_descriptor': No such file or directory