Re: [syzbot] WARNING in cpuset_write_resmask

[syzbot <syzbot+568dc81cd20b72d4a49f-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    e5313968c41b Merge branch 'Split bpf_sk_lookup remote_port..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=113aeefa700000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c40b67275bfe2a58
dashboard link: https://syzkaller.appspot.com/bug?extid=568dc81cd20b72d4a49f
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13bb97ce700000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12062c8e700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+568dc81cd20b72d4a49f-Pl5Pbv+GP7P466ipTTIvnc23WoclnBCfAL8bYrjMMd8@public.gmane.org

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WARNING: CPU: 1 PID: 3647 at kernel/cgroup/cpuset.c:1817 update_nodemasks_hier kernel/cgroup/cpuset.c:1817 [inline]
WARNING: CPU: 1 PID: 3647 at kernel/cgroup/cpuset.c:1817 update_nodemask kernel/cgroup/cpuset.c:1890 [inline]
WARNING: CPU: 1 PID: 3647 at kernel/cgroup/cpuset.c:1817 cpuset_write_resmask+0x167b/0x20f0 kernel/cgroup/cpuset.c:2457
Modules linked in:
CPU: 0 PID: 3647 Comm: syz-executor287 Not tainted 5.16.0-syzkaller-11655-ge5313968c41b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:update_nodemasks_hier kernel/cgroup/cpuset.c:1817 [inline]
RIP: 0010:update_nodemask kernel/cgroup/cpuset.c:1890 [inline]
RIP: 0010:cpuset_write_resmask+0x167b/0x20f0 kernel/cgroup/cpuset.c:2457
Code: 3c 08 00 0f 85 ed 08 00 00 49 8b 9c 24 38 01 00 00 48 89 ef 48 89 de e8 63 4a 04 00 48 39 dd 0f 84 dd ef ff ff e8 e5 46 04 00 <0f> 0b e9 d1 ef ff ff e8 d9 46 04 00 e8 b4 a5 ef ff e8 cf 46 04 00
RSP: 0018:ffffc90003acfb18 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff88801e193a00 RSI: ffffffff81740f0b RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000003 R09: ffffffff8fdeca17
R10: ffffffff81740efd R11: 0000000000000001 R12: ffff888074f2e000
R13: ffff888074f2e054 R14: ffff888074f2e138 R15: 0000000000000000
FS:  00007fee62f33700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcf8240960 CR3: 0000000072ae3000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 cgroup_file_write+0x1de/0x760 kernel/cgroup/cgroup.c:3877
 kernfs_fop_write_iter+0x342/0x500 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2086 [inline]
 new_sync_write+0x431/0x660 fs/read_write.c:503
 vfs_write+0x7cd/0xae0 fs/read_write.c:590
 ksys_write+0x12d/0x250 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fee62f82b79
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fee62f33308 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fee6300c4c8 RCX: 00007fee62f82b79
RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000006
RBP: 00007fee6300c4c0 R08: 0000000000000012 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fee6300c4cc
R13: 00007fee62fd92b0 R14: 6d2e746573757063 R15: 0000000000022000
 </TASK>