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BUG: KCSAN: data-race in mq_clear_sbinfo / test_keyed_super

write to 0xffff88811f70cb70 of 8 bytes by task 12458 on cpu 0:
 mq_clear_sbinfo+0x35/0x50 ipc/mqueue.c:1698
 put_ipc_ns+0x28/0x90 ipc/namespace.c:168
 free_nsproxy+0xb8/0x310 kernel/nsproxy.c:195
 put_nsproxy include/linux/nsproxy.h:105 [inline]
 switch_task_namespaces kernel/nsproxy.c:249 [inline]
 exit_task_namespaces+0x8c/0xa0 kernel/nsproxy.c:254
 do_exit+0x5d1/0x16a0 kernel/exit.c:805
 do_group_exit+0xa5/0x160 kernel/exit.c:935
 get_signal+0x8cf/0x15d0 kernel/signal.c:2862
 arch_do_signal_or_restart+0x8c/0x2e0 arch/x86/kernel/signal.c:868
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x113/0x190 kernel/entry/common.c:207
 irqentry_exit_to_user_mode+0x5/0x10 kernel/entry/common.c:313
 irqentry_exit+0xe/0x40 kernel/entry/common.c:404
 exc_general_protection+0x31a/0x4b0 arch/x86/kernel/traps.c:562
 asm_exc_general_protection+0x1e/0x30

read to 0xffff88811f70cb70 of 8 bytes by task 12433 on cpu 1:
 test_keyed_super+0x1a/0x40 fs/super.c:1077
 sget_fc+0xe8/0x450 fs/super.c:524
 vfs_get_super fs/super.c:1134 [inline]
 get_tree_keyed+0x3f/0x120 fs/super.c:1195
 mqueue_get_tree+0x32/0x40 ipc/mqueue.c:430
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 fc_mount+0x12/0x60 fs/namespace.c:1000
 mq_create_mount ipc/mqueue.c:473 [inline]
 mq_init_ns+0x26d/0x310 ipc/mqueue.c:1689
 create_ipc_ns ipc/namespace.c:58 [inline]
 copy_ipcs+0x211/0x360 ipc/namespace.c:84
 create_new_namespaces+0x137/0x560 kernel/nsproxy.c:90
 copy_namespaces+0x116/0x160 kernel/nsproxy.c:178
 copy_process+0x1428/0x2f30 kernel/fork.c:2167
 kernel_clone+0x15c/0x6a0 kernel/fork.c:2555
 __do_sys_clone kernel/fork.c:2672 [inline]
 __se_sys_clone kernel/fork.c:2656 [inline]
 __x64_sys_clone+0xc6/0xf0 kernel/fork.c:2656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff88811780ac00 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12433 Comm: syz-executor.1 Not tainted 5.17.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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