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EXT4-fs error (device loop3): __ext4_ext_dirty:207: inode #16: comm syz.3.11610: mark_inode_dirty error
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5569: inode #16: comm syz.3.11610: corrupted inode contents
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86c98b70 of 8 bytes by task 3911 on cpu 0:
 data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 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:995
 ext4_check_journal_data_mode+0x16f/0x210 fs/ext4/super.c:5026
 __ext4_fill_super fs/ext4/super.c:5376 [inline]
 ext4_fill_super+0x1c9b/0x37c0 fs/ext4/super.c:5793
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1694
 get_tree_bdev+0x1f/0x30 fs/super.c:1717
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5825
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3760 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3836
 path_mount+0x4d0/0xbc0 fs/namespace.c:4146
 do_mount fs/namespace.c:4159 [inline]
 __do_sys_mount fs/namespace.c:4348 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4325
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4325
 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+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c98b70 of 8 bytes by task 3884 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+0x207/0xae0 kernel/printk/printk_ringbuffer.c:1674
 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_std_error+0x31d/0x350 fs/ext4/super.c:969
 ext4_orphan_del+0x689/0x710 fs/ext4/orphan.c:303
 ext4_truncate+0x89c/0xb00 fs/ext4/inode.c:4584
 ext4_process_orphan+0x110/0x1c0 fs/ext4/orphan.c:337
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:472
 __ext4_fill_super fs/ext4/super.c:5670 [inline]
 ext4_fill_super+0x3408/0x37c0 fs/ext4/super.c:5793
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1694
 get_tree_bdev+0x1f/0x30 fs/super.c:1717
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5825
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3760 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3836
 path_mount+0x4d0/0xbc0 fs/namespace.c:4146
 do_mount fs/namespace.c:4159 [inline]
 __do_sys_mount fs/namespace.c:4348 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4325
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4325
 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+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000595c0 -> 0x00000000000f54e8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3884 Comm: syz.3.11610 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
EXT4-fs error (device loop3) in ext4_orphan_del:303: Corrupt filesystem
loop3: lost filesystem error report for type 5 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5569: inode #16: comm syz.3.11610: corrupted inode contents
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_truncate:4587: inode #16: comm syz.3.11610: mark_inode_dirty error
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3) in ext4_process_orphan:345: Corrupt filesystem
loop3: lost filesystem error report for type 5 error -117
EXT4-fs (loop3): 1 truncate cleaned up
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-0000002a0000 ro without journal. Quota mode: writeback.