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BUG: KCSAN: data-race in vm_area_dup / vma_interval_tree_insert

write to 0xffff888124ae0da8 of 8 bytes by task 20376 on cpu 1:
 rb_link_node include/linux/rbtree.h:75 [inline]
 vma_interval_tree_insert+0x164/0x230 mm/interval_tree.c:23
 __vma_link_file+0xd9/0x110 mm/mmap.c:634
 __vma_adjust+0x1ac/0x12a0 mm/mmap.c:842
 vma_adjust include/linux/mm.h:2276 [inline]
 __split_vma+0x338/0x350 mm/mmap.c:2704
 __do_munmap+0xb02/0xb60 mm/mmap.c:2803
 do_munmap mm/mmap.c:2856 [inline]
 mmap_region+0x165/0xd50 mm/mmap.c:1749
 do_mmap+0x6d4/0xba0 mm/mmap.c:1577
 do_mmap_pgoff include/linux/mm.h:2353 [inline]
 vm_mmap_pgoff+0x12d/0x190 mm/util.c:496
 ksys_mmap_pgoff+0x2d8/0x420 mm/mmap.c:1629
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x91/0xc0 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888124ae0d48 of 200 bytes by task 20377 on cpu 0:
 vm_area_dup+0x70/0xf0 kernel/fork.c:359
 __split_vma+0x88/0x350 mm/mmap.c:2678
 __do_munmap+0xb02/0xb60 mm/mmap.c:2803
 do_munmap mm/mmap.c:2856 [inline]
 mmap_region+0x165/0xd50 mm/mmap.c:1749
 do_mmap+0x6d4/0xba0 mm/mmap.c:1577
 do_mmap_pgoff include/linux/mm.h:2353 [inline]
 vm_mmap_pgoff+0x12d/0x190 mm/util.c:496
 ksys_mmap_pgoff+0x2d8/0x420 mm/mmap.c:1629
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x91/0xc0 arch/x86/kernel/sys_x86_64.c:91
 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: 20377 Comm: blkid Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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