------------[ cut here ]------------
sk->sk_forward_alloc
WARNING: net/ipv4/af_inet.c:162 at inet_sock_destruct+0x62d/0x740, CPU#0: syz.2.19110/20268
Modules linked in:
CPU: 0 UID: 0 PID: 20268 Comm: syz.2.19110 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:inet_sock_destruct+0x62d/0x740
Code: 0f 0b 90 e9 58 fe ff ff e8 e0 2e 9f f7 90 0f 0b 90 e9 8b fe ff ff e8 d2 2e 9f f7 90 0f 0b 90 e9 b1 fe ff ff e8 c4 2e 9f f7 90 <0f> 0b 90 e9 d7 fe ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c 95 fc
RSP: 0018:ffffc90000007d20 EFLAGS: 00010246
RAX: ffffffff8a2674ec RBX: dffffc0000000000 RCX: ffff8881b1708000
RDX: 0000000000000100 RSI: 0000000000000f70 RDI: 0000000000000000
RBP: 0000000000000f70 R08: ffff88804283e8a7 R09: 1ffff11008507d14
R10: dffffc0000000000 R11: ffffed1008507d15 R12: ffff88804283e600
R13: ffff88804283eb08 R14: ffff88804283e88c R15: ffffffff8fead5c0
FS:  00007f10f658b6c0(0000) GS:ffff88818dc93000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f10f65cbfa8 CR3: 00000001d58a4000 CR4: 00000000000006f0
Call Trace:
 <IRQ>
 __sk_destruct+0x8d/0x9d0
 rcu_core+0x7cd/0x1070
 handle_softirqs+0x22a/0x840
 __irq_exit_rcu+0xca/0x220
 irq_exit_rcu+0x9/0x30
 sysvec_apic_timer_interrupt+0xa6/0xc0
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:__kasan_check_byte+0xa/0x40
Code: f6 5b 41 5c 41 5e 41 5f e9 33 fa ff ff 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 41 56 53 48 89 f3 <49> 89 fe e8 3e 15 00 00 84 c0 75 16 be 01 00 00 00 4c 89 f7 31 d2
RSP: 0018:ffffc90029f971e0 EFLAGS: 00000202
RAX: 0000000000000001 RBX: ffffffff823c8576 RCX: 0000000080000003
RDX: 0000000000000000 RSI: ffffffff823c8576 RDI: ffffffff8e95ce20
RBP: ffffffff823c855a R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff94000118991 R12: 0000000000000002
R13: ffffffff8e95ce20 R14: 0000000000000000 R15: 0000000000000000
 lock_acquire+0x84/0x350
 pfn_valid+0xd6/0x480
 page_table_check_clear+0x21/0x4f0
 __zap_vma_range+0x3641/0x4b40
 unmap_vmas+0x379/0x530
 exit_mmap+0x280/0x9e0
 __mmput+0x118/0x430
 exit_mm+0x18e/0x250
 do_exit+0x6a2/0x22c0
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 exit_to_user_mode_loop+0x86/0x480
 ret_from_fork+0x593/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
