KCSAN: data-race in _cma_attach_to_dev / ucma_process

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BUG: KCSAN: data-race in _cma_attach_to_dev / ucma_process_join

write to 0xffff88813f701c00 of 8 bytes by task 5581 on cpu 1:
 _cma_attach_to_dev+0x7d/0x250 drivers/infiniband/core/cma.c:591
 cma_attach_to_dev drivers/infiniband/core/cma.c:602 [inline]
 cma_bind_loopback drivers/infiniband/core/cma.c:3445 [inline]
 cma_resolve_loopback drivers/infiniband/core/cma.c:3514 [inline]
 rdma_resolve_addr+0xda2/0x11e0 drivers/infiniband/core/cma.c:4092
 ucma_resolve_ip+0x13f/0x1c0 drivers/infiniband/core/ucma.c:695
 ucma_write+0x1ab/0x240 drivers/infiniband/core/ucma.c:1744
 vfs_write+0x25c/0x760 fs/read_write.c:582
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88813f701c00 of 8 bytes by task 5583 on cpu 0:
 ucma_get_ctx_dev drivers/infiniband/core/ucma.c:169 [inline]
 ucma_process_join+0x11a/0x580 drivers/infiniband/core/ucma.c:1460
 ucma_join_multicast+0x9e/0xe0 drivers/infiniband/core/ucma.c:1556
 ucma_write+0x1ab/0x240 drivers/infiniband/core/ucma.c:1744
 vfs_write+0x25c/0x760 fs/read_write.c:582
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0xffff88813c302000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5583 Comm: syz-executor.0 Not tainted 6.3.0-rc6-syzkaller-00173-g7a934f4bd7d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
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