KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4d02da97 Merge tag 'net-5.10-rc5' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=156686d5500000
kernel config: https://syzkaller.appspot.com/x/.config?x=73fc125ff8990ab9
dashboard link: https://syzkaller.appspot.com/bug?extid=b763b6bc33001b14b64c
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [cgr...@vger.kernel.org han...@cmpxchg.org linux-...@vger.kernel.org liz...@huawei.com t...@kernel.org]

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b763b6...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in cgroup_freezer_migrate_task / handle_mm_fault

write to 0xffff888100c4c4b8 of 1 bytes by task 8755 on cpu 0:
mem_cgroup_exit_user_fault include/linux/memcontrol.h:659 [inline]
handle_mm_fault+0x145f/0x1770 mm/memory.c:4610
do_user_addr_fault+0x33e/0x730 arch/x86/mm/fault.c:1372
handle_page_fault arch/x86/mm/fault.c:1429 [inline]
exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1485
asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583

read to 0xffff888100c4c4b8 of 1 bytes by task 1 on cpu 1:
cgroup_freezer_migrate_task+0xa9/0x280 kernel/cgroup/freezer.c:239
cgroup_migrate_execute+0x2c5/0x890 kernel/cgroup/cgroup.c:2431
cgroup_migrate kernel/cgroup/cgroup.c:2706 [inline]
cgroup_attach_task+0x1aa/0x300 kernel/cgroup/cgroup.c:2739
__cgroup1_procs_write+0x1a7/0x220 kernel/cgroup/cgroup-v1.c:519
cgroup1_procs_write+0x26/0x30 kernel/cgroup/cgroup-v1.c:532
cgroup_file_write+0x173/0x2f0 kernel/cgroup/cgroup.c:3699
kernfs_fop_write+0x207/0x2c0 fs/kernfs/file.c:315
vfs_write+0x21a/0x7c0 fs/read_write.c:603
ksys_write+0xce/0x180 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:667
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1 Comm: systemd Not tainted 5.10.0-rc4-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.