================================================================== BUG: KCSAN: data-race in data_alloc / data_push_tail write to 0xffffffff88e86ee0 of 8 bytes by task 10376 on cpu 0: data_alloc+0x1d5/0x2e0 kernel/printk/printk_ringbuffer.c:1088 prb_reserve+0x807/0xaf0 kernel/printk/printk_ringbuffer.c:1685 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2448 dump_stack_print_info+0xee/0x1b0 lib/dump_stack.c:57 __dump_stack+0x11/0x30 lib/dump_stack.c:93 dump_stack_lvl+0xe8/0x140 lib/dump_stack.c:120 dump_stack+0x15/0x1b lib/dump_stack.c:129 fail_dump lib/fault-inject.c:73 [inline] should_fail_ex+0x265/0x280 lib/fault-inject.c:174 should_failslab+0x8c/0xb0 mm/failslab.c:46 slab_pre_alloc_hook mm/slub.c:4931 [inline] slab_alloc_node mm/slub.c:5264 [inline] kmem_cache_alloc_node_noprof+0x57/0x4a0 mm/slub.c:5340 __alloc_skb+0x101/0x320 net/core/skbuff.c:660 alloc_skb include/linux/skbuff.h:1383 [inline] netlink_alloc_large_skb+0xbf/0xf0 net/netlink/af_netlink.c:1186 netlink_sendmsg+0x3cf/0x6b0 net/netlink/af_netlink.c:1871 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x145/0x180 net/socket.c:742 ____sys_sendmsg+0x345/0x4e0 net/socket.c:2630 ___sys_sendmsg+0x17b/0x1d0 net/socket.c:2684 __sys_sendmmsg+0x178/0x300 net/socket.c:2773 __do_sys_sendmmsg net/socket.c:2800 [inline] __se_sys_sendmmsg net/socket.c:2797 [inline] __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2797 x64_sys_call+0x1c4a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff88e86ee0 of 8 bytes by task 10372 on cpu 1: data_make_reusable kernel/printk/printk_ringbuffer.c:591 [inline] data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:676 data_realloc kernel/printk/printk_ringbuffer.c:1158 [inline] prb_reserve_in_last+0x815/0xba0 kernel/printk/printk_ringbuffer.c:1456 vprintk_store+0x494/0x860 kernel/printk/printk.c:2273 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2448 __ext4_grp_locked_error+0x5bf/0x7b0 fs/ext4/super.c:1061 mb_free_blocks+0xb97/0xbc0 fs/ext4/mballoc.c:2014 ext4_mb_clear_bb fs/ext4/mballoc.c:6638 [inline] ext4_free_blocks+0xded/0x1480 fs/ext4/mballoc.c:6770 ext4_remove_blocks fs/ext4/extents.c:2551 [inline] ext4_ext_rm_leaf fs/ext4/extents.c:2716 [inline] ext4_ext_remove_space+0x177b/0x2900 fs/ext4/extents.c:2965 ext4_ext_truncate+0xc7/0x170 fs/ext4/extents.c:4484 ext4_truncate+0x70d/0xae0 fs/ext4/inode.c:4614 ext4_process_orphan+0x110/0x1c0 fs/ext4/orphan.c:335 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:470 __ext4_fill_super fs/ext4/super.c:5617 [inline] ext4_fill_super+0x3483/0x3810 fs/ext4/super.c:5736 get_tree_bdev_flags+0x291/0x300 fs/super.c:1698 get_tree_bdev+0x1f/0x30 fs/super.c:1721 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5768 vfs_get_tree+0x57/0x1d0 fs/super.c:1758 fc_mount fs/namespace.c:1199 [inline] do_new_mount_fc fs/namespace.c:3642 [inline] do_new_mount+0x24d/0x660 fs/namespace.c:3718 path_mount+0x4a5/0xb70 fs/namespace.c:4028 do_mount fs/namespace.c:4041 [inline] __do_sys_mount fs/namespace.c:4229 [inline] __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4206 __x64_sys_mount+0x67/0x80 fs/namespace.c:4206 x64_sys_call+0x2b51/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000000100004a5e -> 0x0000000100005623 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 10372 Comm: syz.7.13067 Tainted: G W syzkaller #0 PREEMPT(voluntary) Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025 ================================================================== block 144:freeing already freed block (bit 9); block bitmap corrupt. EXT4-fs error (device loop7): ext4_do_update_inode:5632: inode #13: comm syz.7.13067: corrupted inode contents EXT4-fs error (device loop7): ext4_dirty_inode:6517: inode #13: comm syz.7.13067: mark_inode_dirty error EXT4-fs error (device loop7): ext4_do_update_inode:5632: inode #13: comm syz.7.13067: corrupted inode contents EXT4-fs error (device loop7): __ext4_ext_dirty:206: inode #13: comm syz.7.13067: mark_inode_dirty error EXT4-fs error (device loop7): ext4_do_update_inode:5632: inode #13: comm syz.7.13067: corrupted inode contents EXT4-fs error (device loop7) in ext4_orphan_del:301: Corrupt filesystem EXT4-fs error (device loop7): ext4_do_update_inode:5632: inode #13: comm syz.7.13067: corrupted inode contents EXT4-fs error (device loop7): ext4_truncate:4637: inode #13: comm syz.7.13067: mark_inode_dirty error EXT4-fs error (device loop7) in ext4_process_orphan:343: Corrupt filesystem EXT4-fs (loop7): 1 truncate cleaned up