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BUG: KCSAN: data-race in fuse_get_req / fuse_set_initialized

read to 0xffff88810bf5f104 of 4 bytes by task 26954 on cpu 1:
 fuse_block_alloc fs/fuse/dev.c:86 [inline]
 fuse_get_req+0xb6/0x450 fs/fuse/dev.c:113
 fuse_simple_request+0x7f/0x640 fs/fuse/dev.c:492
 fuse_send_open.isra.0+0x193/0x1d0 fs/fuse/file.c:53
 fuse_do_open+0x1e2/0x320 fs/fuse/file.c:149
 fuse_open_common+0xe5/0x1f0 fs/fuse/file.c:233
 fuse_dir_open+0x2c/0x40 fs/fuse/dir.c:1274
 do_dentry_open+0x301/0x970 fs/open.c:797
 vfs_open+0x62/0x80 fs/open.c:914
 do_last fs/namei.c:3408 [inline]
 path_openat+0xf73/0x36e0 fs/namei.c:3525
 do_filp_open+0x11e/0x1b0 fs/namei.c:3555
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88810bf5f104 of 4 bytes by task 26955 on cpu 0:
 fuse_set_initialized+0x22/0x40 fs/fuse/dev.c:81
 process_init_reply+0x96/0xb90 fs/fuse/inode.c:969
 fuse_request_end+0x324/0x530 fs/fuse/dev.c:328
 fuse_dev_do_write+0x582/0x1bd0 fs/fuse/dev.c:1911
 fuse_dev_write+0xba/0x100 fs/fuse/dev.c:1933
 call_write_iter include/linux/fs.h:1895 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 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: 26955 Comm: syz-executor.1 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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