KCSAN: data-race in ucma_create_id / ucma_get

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in ucma_create_id / ucma_get_ctx (2) rdma				1	1364d	1364d	0/26	auto-closed as invalid on 2020/09/03 16:57

================================================================== BUG: KCSAN: data-race in ucma_create_id / ucma_get_ctx read to 0xffff888122d52340 of 8 bytes by task 5284 on cpu 1: _ucma_find_context drivers/infiniband/core/ucma.c:140 [inline] ucma_get_ctx+0x8f/0xf0 drivers/infiniband/core/ucma.c:150 ucma_resolve_ip+0xb5/0x180 drivers/infiniband/core/ucma.c:704 ucma_write+0x1fe/0x2a0 drivers/infiniband/core/ucma.c:1684 __vfs_write+0x67/0xc0 fs/read_write.c:494 vfs_write fs/read_write.c:558 [inline] vfs_write+0x18a/0x390 fs/read_write.c:542 ksys_write+0x17b/0x1b0 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x4c/0x60 fs/read_write.c:620 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 write to 0xffff888122d52340 of 8 bytes by task 5279 on cpu 0: ucma_create_id+0x1d5/0x380 drivers/infiniband/core/ucma.c:515 ucma_write+0x1fe/0x2a0 drivers/infiniband/core/ucma.c:1684 __vfs_write+0x67/0xc0 fs/read_write.c:494 vfs_write fs/read_write.c:558 [inline] vfs_write+0x18a/0x390 fs/read_write.c:542 ksys_write+0x17b/0x1b0 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x4c/0x60 fs/read_write.c:620 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 5279 Comm: syz-executor.2 Not tainted 5.4.0-rc7+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================