KCSAN: data-race in vm_area_dup / vma_interval_tree_insert (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: f60f0f54 kcsan: Expose core configuration parameters as mo..
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=12ac4231e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4b77cdbe9348e50e
dashboard link: https://syzkaller.appspot.com/bug?extid=c76913c4746a5ba434d5
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org el...@google.com]

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+c76913...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in vm_area_dup / vma_interval_tree_insert

write to 0xffff88811db30380 of 8 bytes by task 8046 on cpu 0:
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_link+0xab/0x130 mm/mmap.c:660
mmap_region+0x85e/0xd50 mm/mmap.c:1807
do_mmap+0x6c8/0xba0 mm/mmap.c:1555
do_mmap_pgoff include/linux/mm.h:2338 [inline]
vm_mmap_pgoff+0x12d/0x190 mm/util.c:506
ksys_mmap_pgoff+0x2d8/0x420 mm/mmap.c:1607
__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+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811db30320 of 200 bytes by task 8045 on cpu 1:
vm_area_dup+0x70/0xf0 kernel/fork.c:362
__split_vma+0x88/0x350 mm/mmap.c:2656
split_vma+0x73/0xa0 mm/mmap.c:2714
mprotect_fixup+0x3e8/0x510 mm/mprotect.c:407
do_mprotect_pkey+0x3eb/0x660 mm/mprotect.c:553
__do_sys_mprotect mm/mprotect.c:578 [inline]
__se_sys_mprotect mm/mprotect.c:575 [inline]
__x64_sys_mprotect+0x51/0x70 mm/mprotect.c:575
do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8045 Comm: modprobe Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.