loop3: detected capacity change from 0 to 512
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86c76998 of 8 bytes by task 16770 on cpu 0:
 data_alloc+0x308/0x380 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1727
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 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
 __quota_error+0x102/0x110 fs/quota/dquot.c:148
 write_blk fs/quota/quota_tree.c:73 [inline]
 get_free_dqblk+0x248/0x320 fs/quota/quota_tree.c:136
 do_insert_tree+0x197/0xad0 fs/quota/quota_tree.c:347
 do_insert_tree+0x76f/0xad0 fs/quota/quota_tree.c:402
 do_insert_tree+0x76f/0xad0 fs/quota/quota_tree.c:402
 do_insert_tree+0x76f/0xad0 fs/quota/quota_tree.c:402
 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:7037
 dqget+0x51f/0x8b0 fs/quota/dquot.c:1002
 __dquot_initialize+0x28c/0x7c0 fs/quota/dquot.c:1530
 dquot_initialize+0x1a/0x30 fs/quota/dquot.c:1592
 ext4_process_orphan+0x2d/0x1c0 fs/ext4/orphan.c:327
 ext4_orphan_cleanup+0x6a6/0xa10 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5705 [inline]
 ext4_fill_super+0x33ab/0x3760 fs/ext4/super.c:5828
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1634
 get_tree_bdev+0x1f/0x30 fs/super.c:1657
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5860
 vfs_get_tree+0x57/0x1d0 fs/super.c:1694
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3841
 path_mount+0x4ad/0xb90 fs/namespace.c:4161
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4367
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4367
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c76998 of 8 bytes by task 16773 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline]
 prb_reserve+0x21a/0xaf0 kernel/printk/printk_ringbuffer.c:1677
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 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
 ext4_check_journal_data_mode+0x16f/0x210 fs/ext4/super.c:5060
 __ext4_fill_super fs/ext4/super.c:5410 [inline]
 ext4_fill_super+0x1bed/0x3760 fs/ext4/super.c:5828
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1634
 get_tree_bdev+0x1f/0x30 fs/super.c:1657
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5860
 vfs_get_tree+0x57/0x1d0 fs/super.c:1694
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3841
 path_mount+0x4ad/0xb90 fs/namespace.c:4161
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4367
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4367
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xfffffffffffff320 -> 0x00000000000ac818

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 16773 Comm: syz.3.3376 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================
EXT4-fs (loop3): encrypted files will use data=ordered instead of data journaling mode
EXT4-fs error (device loop3): ext4_mb_generate_buddy:1317: group 0, 
block bitmap and bg descriptor inconsistent: 191 vs 220 free clusters
EXT4-fs (loop3): 1 truncate cleaned up
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.