__dump_stack+0x1d/0x30 lib/dump_stack.c:94 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_fail+0xb/0x20 lib/fault-inject.c:184 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 _inline_copy_to_user include/linux/uaccess.h:193 [inline] _copy_to_user+0x20/0xa0 lib/usercopy.c:26 ================================================================== BUG: KCSAN: data-race in data_push_tail / string write to 0xffffffff88e392d0 of 1 bytes by task 6962 on cpu 1: string_nocheck lib/vsprintf.c:643 [inline] string+0x187/0x220 lib/vsprintf.c:721 vsnprintf+0x532/0x890 lib/vsprintf.c:2874 vscnprintf+0x41/0x90 lib/vsprintf.c:2939 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 __ext4_msg+0x18f/0x1a0 fs/ext4/super.c:981 ext4_check_descriptors fs/ext4/super.c:3321 [inline] ext4_group_desc_init+0xedb/0x14e0 fs/ext4/super.c:4887 __ext4_fill_super fs/ext4/super.c:5347 [inline] ext4_fill_super+0x1dbb/0x34e0 fs/ext4/super.c:5724 get_tree_bdev_flags+0x291/0x300 fs/super.c:1679 get_tree_bdev+0x1f/0x30 fs/super.c:1702 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5756 vfs_get_tree+0x54/0x1d0 fs/super.c:1802 do_new_mount+0x207/0x680 fs/namespace.c:3856 path_mount+0x4a4/0xb20 fs/namespace.c:4180 do_mount fs/namespace.c:4193 [inline] __do_sys_mount fs/namespace.c:4404 [inline] __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4381 __x64_sys_mount+0x67/0x80 fs/namespace.c:4381 x64_sys_call+0xd36/0x2fb0 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 read to 0xffffffff88e392d0 of 8 bytes by task 7018 on cpu 0: data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline] data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82 _printk+0x79/0xa0 kernel/printk/printk.c:2475 printk_stack_address arch/x86/kernel/dumpstack.c:70 [inline] show_trace_log_lvl+0x4e3/0x560 arch/x86/kernel/dumpstack.c:282 __dump_stack+0x1d/0x30 lib/dump_stack.c:94 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_fail+0xb/0x20 lib/fault-inject.c:184 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37 _inline_copy_to_user include/linux/uaccess.h:193 [inline] _copy_to_user+0x20/0xa0 lib/usercopy.c:26 copy_to_user include/linux/uaccess.h:225 [inline] simple_read_from_buffer+0xb5/0x130 fs/libfs.c:1122 proc_fail_nth_read+0x100/0x140 fs/proc/base.c:1482 vfs_read+0x1a0/0x6f0 fs/read_write.c:570 ksys_read+0xda/0x1a0 fs/read_write.c:715 __do_sys_read fs/read_write.c:724 [inline] __se_sys_read fs/read_write.c:722 [inline] __x64_sys_read+0x40/0x50 fs/read_write.c:722 x64_sys_call+0x2d77/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:1 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: 0x00000000ffffe4c6 -> 0x2073662d34545845 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 7018 Comm: syz.3.1272 Not tainted 6.15.0-syzkaller-09161-g0f70f5b08a47 #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 ================================================================== copy_to_user include/linux/uaccess.h:225 [inline] simple_read_from_buffer+0xb5/0x130 fs/libfs.c:1122 proc_fail_nth_read+0x100/0x140 fs/proc/base.c:1482 vfs_read+0x1a0/0x6f0 fs/read_write.c:570 ksys_read+0xda/0x1a0 fs/read_write.c:715 __do_sys_read fs/read_write.c:724 [inline] __se_sys_read fs/read_write.c:722 [inline] __x64_sys_read+0x40/0x50 fs/read_write.c:722 x64_sys_call+0x2d77/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:1 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 RIP: 0033:0x7fbe6d47d37c Code: ec 28 48 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 99 93 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 34 44 89 c7 48 89 44 24 08 e8 ef 93 02 00 48 RSP: 002b:00007fbe6bae7030 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007fbe6d6a5fa0 RCX: 00007fbe6d47d37c RDX: 000000000000000f RSI: 00007fbe6bae70a0 RDI: 0000000000000007 RBP: 00007fbe6bae7090 R08: 0000000000000000 R09: 0000000000000000 R10: 00002000000002c0 R11: 0000000000000246 R12: 0000000000000001 R13: 0000000000000000 R14: 00007fbe6d6a5fa0 R15: 00007ffccec2e858