syzbot has found a reproducer for the following issue on: HEAD commit: 2f111a6fd5b5 Merge tag 'ceph-for-5.15-rc7' of git://github.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13e33db4b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=1f7f46d98a0da80e dashboard link: https://syzkaller.appspot.com/bug?extid=08e6343a8cbd89b0c9d8 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=10f70630b00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1033ffecb00000 The issue was bisected to: commit 2a61d8b883bbad26b06d2e6cc3777a697e78830d Author: Taehee Yoo <ap420073@xxxxxxxxx> Date: Mon Nov 5 09:23:13 2018 +0000 netfilter: ipt_CLUSTERIP: fix sleep-in-atomic bug in clusterip_config_entry_put() bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16ce2121300000 final oops: https://syzkaller.appspot.com/x/report.txt?x=15ce2121300000 console output: https://syzkaller.appspot.com/x/log.txt?x=11ce2121300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+08e6343a8cbd89b0c9d8@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 2a61d8b883bb ("netfilter: ipt_CLUSTERIP: fix sleep-in-atomic bug in clusterip_config_entry_put()") ------------[ cut here ]------------ proc_dir_entry 'ipt_CLUSTERIP/224.0.0.1' already registered WARNING: CPU: 1 PID: 24819 at fs/proc/generic.c:376 proc_register+0x34c/0x700 fs/proc/generic.c:376 Modules linked in: CPU: 1 PID: 24819 Comm: syz-executor269 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:proc_register+0x34c/0x700 fs/proc/generic.c:376 Code: df 48 89 f9 48 c1 e9 03 80 3c 01 00 0f 85 5d 03 00 00 48 8b 44 24 28 48 c7 c7 e0 b1 9c 89 48 8b b0 d8 00 00 00 e8 a0 2c 01 07 <0f> 0b 48 c7 c7 40 ac b4 8b e8 26 c0 46 07 48 8b 4c 24 38 48 b8 00 RSP: 0018:ffffc900041df268 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff88806ca35580 RSI: ffffffff815e88a8 RDI: fffff5200083be3f RBP: ffff88801af3c838 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff815e264e R11: 0000000000000000 R12: ffff88801ee5b498 R13: ffff88801ee5bd40 R14: dffffc0000000000 R15: 0000000000000009 FS: 00007f976a6aa700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f976a6aa718 CR3: 00000000697b9000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: proc_create_data+0x130/0x190 fs/proc/generic.c:575 clusterip_config_init net/ipv4/netfilter/ipt_CLUSTERIP.c:292 [inline] clusterip_tg_check+0x1b83/0x2300 net/ipv4/netfilter/ipt_CLUSTERIP.c:517 xt_check_target+0x26c/0x9e0 net/netfilter/x_tables.c:1038 check_target net/ipv4/netfilter/ip_tables.c:511 [inline] find_check_entry.constprop.0+0x7a9/0x9a0 net/ipv4/netfilter/ip_tables.c:553 translate_table+0xc26/0x16a0 net/ipv4/netfilter/ip_tables.c:717 do_replace net/ipv4/netfilter/ip_tables.c:1135 [inline] do_ipt_set_ctl+0x56e/0xb80 net/ipv4/netfilter/ip_tables.c:1629 nf_setsockopt+0x83/0xe0 net/netfilter/nf_sockopt.c:101 ip_setsockopt+0x3c3/0x3a60 net/ipv4/ip_sockglue.c:1435 tcp_setsockopt+0x136/0x2530 net/ipv4/tcp.c:3658 __sys_setsockopt+0x2db/0x610 net/socket.c:2176 __do_sys_setsockopt net/socket.c:2187 [inline] __se_sys_setsockopt net/socket.c:2184 [inline] __x64_sys_setsockopt+0xba/0x150 net/socket.c:2184 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: 0033:0x7f976af2bd19 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f976a6aa208 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007f976afb4278 RCX: 00007f976af2bd19 RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00007f976afb4270 R08: 0000000000000298 R09: 0000000000000000 R10: 00000000200002c0 R11: 0000000000000246 R12: 00007f976afb427c R13: 00007fff7aa240bf R14: 00007f976a6aa300 R15: 0000000000022000