EXT4-fs (loop6): 1 truncate cleaned up
EXT4-fs (loop6): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KCSAN: data-race in desc_read_finalized_seq / prb_reserve

write to 0xffffffff86918890 of 8 bytes by task 29124 on cpu 0:
 prb_reserve+0x750/0xb80 kernel/printk/printk_ringbuffer.c:-1
 vprintk_store+0x552/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x1a0/0x6c0 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x7f/0xb0 kernel/printk/printk.c:2475
 set_capacity_and_notify+0x155/0x200 block/genhd.c:93
 loop_set_size+0x2e/0x70 drivers/block/loop.c:210
 loop_configure+0x89c/0xa30 drivers/block/loop.c:1120
 lo_ioctl+0x5fa/0x1570 drivers/block/loop.c:-1
 blkdev_ioctl+0x35b/0x450 block/ioctl.c:698
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
 x64_sys_call+0x168d/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86918890 of 8 bytes by task 29121 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 desc_read_finalized_seq+0x163/0x280 kernel/printk/printk_ringbuffer.c:1874
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x142/0x710 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x42/0x70 kernel/printk/printk_ringbuffer.c:2185
 printk_get_next_message+0xdc/0x530 kernel/printk/printk.c:3005
 console_emit_next_record kernel/printk/printk.c:3092 [inline]
 console_flush_all+0x2a9/0x7a0 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xf4/0x350 kernel/printk/printk.c:3325
 vprintk_emit+0x470/0x6c0 kernel/printk/printk.c:2450
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x7f/0xb0 kernel/printk/printk.c:2475
 __ext4_msg+0x198/0x1b0 fs/ext4/super.c:985
 ext4_fill_super+0x17d1/0x3580 fs/ext4/super.c:5741
 get_tree_bdev_flags+0x2b4/0x330 fs/super.c:1636
 get_tree_bdev+0x1f/0x30 fs/super.c:1659
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5758
 vfs_get_tree+0x56/0x1e0 fs/super.c:1759
 do_new_mount+0x246/0x6b0 fs/namespace.c:3879
 path_mount+0x49b/0xb30 fs/namespace.c:4206
 do_mount fs/namespace.c:4219 [inline]
 __do_sys_mount fs/namespace.c:4430 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4407
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4407
 x64_sys_call+0xd11/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000001712 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 29121 Comm: syz.6.7794 Not tainted 6.15.0-rc1-syzkaller-00095-g2eb959eeecc6 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================
EXT4-fs warning (device loop6): ext4_lookup:1801: Inconsistent encryption contexts: 2/12