syzbot

0-2
==================================================================
BUG: KCSAN: data-race in data_alloc / data_push_tail

write to 0xffffffff89385718 of 8 bytes by interrupt on cpu 1:
 data_alloc+0x259/0x390 kernel/printk/printk_ringbuffer.c:1116
 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
 print_daily_error_info+0x210/0x300 fs/ext4/super.c:3680
 call_timer_fn+0x3b/0x2a0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1799 [inline]
 __run_timers kernel/time/timer.c:2373 [inline]
 __run_timer_base+0x426/0x620 kernel/time/timer.c:2385
 run_timer_base kernel/time/timer.c:2394 [inline]
 run_timer_softirq+0x31/0x70 kernel/time/timer.c:2404
 handle_softirqs+0xb9/0x2a0 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x39/0xc0 kernel/softirq.c:723
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
 sysvec_apic_timer_interrupt+0x74/0x80 arch/x86/kernel/apic/apic.c:1056
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
 console_trylock_spinning kernel/printk/printk.c:-1 [inline]
 vprintk_emit+0x3d3/0x600 kernel/printk/printk.c:2478
 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_grp_locked_error+0x56d/0x7d0 fs/ext4/super.c:1061
 mb_free_blocks+0xb97/0xbc0 fs/ext4/mballoc.c:2044
 ext4_mb_clear_bb fs/ext4/mballoc.c:6656 [inline]
 ext4_free_blocks+0xdfe/0x14a0 fs/ext4/mballoc.c:6788
 ext4_remove_blocks fs/ext4/extents.c:2554 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2719 [inline]
 ext4_ext_remove_space+0x18a7/0x29d0 fs/ext4/extents.c:2964
 ext4_ext_truncate+0xc7/0x160 fs/ext4/extents.c:4537
 ext4_truncate+0x70a/0xb00 fs/ext4/inode.c:4564
 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:5668 [inline]
 ext4_fill_super+0x3408/0x37c0 fs/ext4/super.c:5791
 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:5823
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3839
 path_mount+0x4d0/0xbc0 fs/namespace.c:4159
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4338
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4338
 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 0xffffffff89385718 of 8 bytes by task 8706 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:608 [inline]
 data_push_tail+0x100/0x470 kernel/printk/printk_ringbuffer.c:693
 data_alloc+0x11b/0x390 kernel/printk/printk_ringbuffer.c:1089
 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
 debug_print_tree+0x9b/0x120 fs/ext4/block_validity.c:138
 ext4_setup_system_zone+0x453/0x640 fs/ext4/block_validity.c:265
 __ext4_fill_super fs/ext4/super.c:5594 [inline]
 ext4_fill_super+0x3095/0x37c0 fs/ext4/super.c:5791
 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:5823
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3763 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3839
 path_mount+0x4d0/0xbc0 fs/namespace.c:4159
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4338
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4338
 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: 0x00000000ffffecee -> 0x00000000fffff857

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8706 Comm: syz.0.1252 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================
, 18-18
, 34-34

EXT4-fs error (device loop0): ext4_orphan_get:1417: comm syz.0.1252: bad orphan inode 15
loop0: lost filesystem error report for type 5 error -117
ext4_test_bit(bit=14, block=18) = 1
is_bad_inode(inode)=0
NEXT_ORPHAN(inode)=2264924160
max_ino=32
i_nlink=0
EXT4-fs error (device loop0): ext4_do_update_inode:5569: inode #15: comm syz.0.1252: corrupted inode contents
loop0: lost file I/O error report for ino 15 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop0): ext4_dirty_inode:6450: inode #15: comm syz.0.1252: mark_inode_dirty error
loop0: lost file I/O error report for ino 15 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop0): ext4_do_update_inode:5569: inode #15: comm syz.0.1252: corrupted inode contents
loop0: lost file I/O error report for ino 15 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop0): ext4_xattr_delete_inode:2999: inode #15: comm syz.0.1252: mark_inode_dirty error
EXT4-fs error (device loop0): ext4_xattr_delete_inode:3002: inode #15: comm syz.0.1252: mark inode dirty (error -117)
EXT4-fs warning (device loop0): ext4_evict_inode:275: xattr delete (err -117)