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BUG: KCSAN: data-race in strncpy / strscpy

write to 0xffff888132d64738 of 8 bytes by task 4211 on cpu 1:
 strscpy+0x138/0x170 lib/string.c:162
 strscpy_pad+0x23/0x80 lib/string_helpers.c:835
 __set_task_comm+0x3b/0x110 fs/exec.c:1231
 set_task_comm include/linux/sched.h:1978 [inline]
 __kthread_create_on_node+0x2aa/0x320 kernel/kthread.c:474
 kthread_create_on_node+0x86/0xb0 kernel/kthread.c:512
 init_rescuer+0x10e/0x190 kernel/workqueue.c:4272
 alloc_workqueue+0x7c3/0xa70 kernel/workqueue.c:4347
 __ext4_fill_super fs/ext4/super.c:5370 [inline]
 ext4_fill_super+0x3718/0x4500 fs/ext4/super.c:5644
 get_tree_bdev+0x2b4/0x3b0 fs/super.c:1282
 ext4_get_tree+0x18/0x20 fs/ext4/super.c:5675
 vfs_get_tree+0x49/0x190 fs/super.c:1489
 do_new_mount+0x200/0x650 fs/namespace.c:3145
 path_mount+0x4aa/0xb70 fs/namespace.c:3475
 do_mount fs/namespace.c:3488 [inline]
 __do_sys_mount fs/namespace.c:3697 [inline]
 __se_sys_mount+0x281/0x2d0 fs/namespace.c:3674
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3674
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888132d64738 of 1 bytes by task 4218 on cpu 0:
 strncpy+0xc7/0x160 lib/string.c:96
 set_cmdline kernel/trace/trace.c:2240 [inline]
 trace_save_cmdline kernel/trace/trace.c:2452 [inline]
 tracing_record_taskinfo_sched_switch+0x20f/0x610 kernel/trace/trace.c:2592
 probe_sched_switch+0x7c/0x90 kernel/trace/trace_sched_switch.c:35
 __traceiter_sched_switch+0x45/0x60 include/trace/events/sched.h:222
 trace_sched_switch include/trace/events/sched.h:222 [inline]
 __schedule+0x6d4/0x6f0 kernel/sched/core.c:6552
 schedule+0x51/0x80 kernel/sched/core.c:6631
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6690
 kthread+0x129/0x1e0 kernel/kthread.c:369
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

value changed: 0x00 -> 0x2d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4218 Comm: ext4-rsv-conver Tainted: G        W          6.2.0-rc2-syzkaller-00010-g69b41ac87e4a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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