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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve_in_last

write to 0xffffffff86e7d9c0 of 8 bytes by interrupt on cpu 1:
 data_realloc kernel/printk/printk_ringbuffer.c:1228 [inline]
 prb_reserve_in_last+0x9c7/0xae0 kernel/printk/printk_ringbuffer.c:1498
 vprintk_store+0x45b/0x910 kernel/printk/printk.c:2328
 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
 print_daily_error_info+0x2c7/0x300 fs/ext4/super.c:3726
 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:758
 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
 __preempt_count_dec_and_test arch/x86/include/asm/preempt.h:123 [inline]
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:220 [inline]
 _raw_spin_unlock_irq+0x12/0x30 kernel/locking/spinlock.c:229
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 loop_queue_work drivers/block/loop.c:873 [inline]
 loop_queue_rq+0x5dc/0x680 drivers/block/loop.c:1913
 __blk_mq_issue_directly block/blk-mq.c:2694 [inline]
 blk_mq_try_issue_directly+0x254/0x4b0 block/blk-mq.c:2754
 blk_mq_submit_bio+0xdc7/0x1120 block/blk-mq.c:3208
 __submit_bio+0x54/0x3d0 block/blk-core.c:673
 __submit_bio_noacct_mq block/blk-core.c:756 [inline]
 submit_bio_noacct_nocheck+0x153/0x620 block/blk-core.c:790
 submit_bio_noacct+0x760/0x980 block/blk-core.c:925
 submit_bio+0x2a4/0x2c0 block/blk-core.c:966
 blk_crypto_submit_bio include/linux/blk-crypto.h:212 [inline]
 __bh_submit+0x33f/0x380 fs/buffer.c:1132
 bh_submit+0x26/0x30 fs/buffer.c:1146
 ext4_commit_super+0x19c/0x260 fs/ext4/super.c:6357
 ext4_handle_error+0x46f/0x570 fs/ext4/super.c:725
 __ext4_error_inode+0x1af/0x3a0 fs/ext4/super.c:871
 __check_block_validity fs/ext4/inode.c:402 [inline]
 ext4_map_blocks+0x6cf/0x9a0 fs/ext4/inode.c:-1
 ext4_getblk+0x135/0x540 fs/ext4/inode.c:991
 ext4_bread+0x28/0x110 fs/ext4/inode.c:1054
 ext4_quota_write+0x166/0x360 fs/ext4/super.c:7433
 v2_write_file_info+0x1bd/0x260 fs/quota/quota_v2.c:218
 dquot_acquire+0x25b/0x2b0 fs/quota/dquot.c:501
 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 0xffffffff86e7d9b8 of 16 bytes by task 2973 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1934 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1982 [inline]
 _prb_read_valid+0x183/0x930 kernel/printk/printk_ringbuffer.c:2173
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2245
 syslog_print+0x164/0x560 kernel/printk/printk.c:1612
 do_syslog+0x52b/0x7f0 kernel/printk/printk.c:1763
 __do_sys_syslog kernel/printk/printk.c:1855 [inline]
 __se_sys_syslog kernel/printk/printk.c:1853 [inline]
 __x64_sys_syslog+0x41/0x50 kernel/printk/printk.c:1853
 x64_sys_call+0x1d36/0x2550 arch/x86/include/generated/asm/syscalls_64.h:104
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 2973 Comm: klogd Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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