==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86c7e3b0 of 8 bytes by task 21944 on cpu 1:
 data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8d6/0xad0 kernel/printk/printk_ringbuffer.c:1727
 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_warning_inode+0x184/0x1a0 fs/ext4/super.c:1043
 dx_probe+0x924/0x990 fs/ext4/namei.c:933
 ext4_dx_find_entry fs/ext4/namei.c:1721 [inline]
 __ext4_find_entry+0x35a/0xdf0 fs/ext4/namei.c:1561
 ext4_lookup_entry fs/ext4/namei.c:1703 [inline]
 ext4_lookup+0xcd/0x3a0 fs/ext4/namei.c:1769
 __lookup_slow+0x19d/0x260 fs/namei.c:1915
 lookup_slow+0x3c/0x60 fs/namei.c:1932
 walk_component fs/namei.c:2278 [inline]
 lookup_last fs/namei.c:2785 [inline]
 path_lookupat+0x2f7/0x500 fs/namei.c:2809
 filename_lookup+0x190/0x390 fs/namei.c:2838
 kern_path+0x3b/0xf0 fs/namei.c:3044
 create_local_trace_uprobe+0x53/0x2d0 kernel/trace/trace_uprobe.c:1632
 perf_uprobe_init+0xc0/0x150 kernel/trace/trace_event_perf.c:319
 perf_uprobe_event_init+0xc4/0x140 kernel/events/core.c:11612
 perf_try_init_event+0x254/0x6e0 kernel/events/core.c:13068
 perf_init_event kernel/events/core.c:13166 [inline]
 perf_event_alloc+0xb2f/0x1a10 kernel/events/core.c:13441
 __do_sys_perf_event_open kernel/events/core.c:13963 [inline]
 __se_sys_perf_event_open+0x4b8/0x1270 kernel/events/core.c:13844
 __x64_sys_perf_event_open+0x67/0x80 kernel/events/core.c:13844
 x64_sys_call+0x2789/0x3020 arch/x86/include/generated/asm/syscalls_64.h:299
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c7e3b0 of 8 bytes by task 21946 on cpu 0:
 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+0x216/0xad0 kernel/printk/printk_ringbuffer.c:1677
 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_warning_inode+0x184/0x1a0 fs/ext4/super.c:1043
 dx_probe+0x728/0x990 fs/ext4/namei.c:-1
 ext4_dx_find_entry fs/ext4/namei.c:1721 [inline]
 __ext4_find_entry+0x35a/0xdf0 fs/ext4/namei.c:1561
 ext4_lookup_entry fs/ext4/namei.c:1703 [inline]
 ext4_lookup+0xcd/0x3a0 fs/ext4/namei.c:1769
 lookup_open fs/namei.c:4484 [inline]
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0xbf0/0x2050 fs/namei.c:4855
 do_file_open+0x16c/0x290 fs/namei.c:4887
 do_open_execat+0xab/0x240 fs/exec.c:781
 alloc_bprm+0x25/0x350 fs/exec.c:1401
 class_bprm_constructor fs/exec.c:1466 [inline]
 do_execveat_common+0x104/0x720 fs/exec.c:1799
 __do_sys_execveat fs/exec.c:1941 [inline]
 __se_sys_execveat fs/exec.c:1934 [inline]
 __x64_sys_execveat+0x76/0xa0 fs/exec.c:1934
 x64_sys_call+0x2a33/0x3020 arch/x86/include/generated/asm/syscalls_64.h:323
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000018f98 -> 0x00000000000d8e10

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21946 Comm: syz.7.5076 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================
EXT4-fs warning (device loop7): dx_probe:837: inode #2: comm syz.7.5076: Unimplemented hash flags: 0x0001
EXT4-fs warning (device loop7): dx_probe:934: inode #2: comm syz.7.5076: Corrupt directory, running e2fsck is recommended