general protection fault in list_lru_del

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    63623fd4 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1492da55e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9833e26bab355358
dashboard link: https://syzkaller.appspot.com/bug?extid=34c3a8c021ca80c808b0
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)

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+34c3a8c021ca80c808b0@xxxxxxxxxxxxxxxxxxxxxxxxx

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 11205 Comm: kworker/u4:4 Not tainted 5.6.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_tcp_accept_worker
RIP: 0010:__list_del_entry_valid+0x85/0xf5 lib/list_debug.c:51
Code: 0f 84 e1 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c4 0f 84 e2 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 53 49 8b 14 24 4c 39 f2 0f 85 99 00 00 00 49 8d 7d
RSP: 0018:ffffc90001b27af0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff888020040c60 RCX: ffffffff81a1dda6
RDX: 0000000000000000 RSI: ffffffff81a1dba1 RDI: ffff888020040c68
RBP: ffffc90001b27b08 R08: ffff88809f18e280 R09: fffff52000364f51
R10: fffff52000364f50 R11: 0000000000000003 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888020040c60 R15: ffff888020040c68
FS:  0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f78a44de000 CR3: 000000008c993000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000006920 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __list_del_entry include/linux/list.h:132 [inline]
 list_del_init include/linux/list.h:204 [inline]
 list_lru_del+0x11d/0x620 mm/list_lru.c:158
 inode_lru_list_del fs/inode.c:450 [inline]
 iput_final fs/inode.c:1568 [inline]
 iput+0x52c/0x900 fs/inode.c:1597
 __sock_release+0x20e/0x280 net/socket.c:617
 sock_release+0x18/0x20 net/socket.c:625
 rds_tcp_accept_one+0x5a9/0xc00 net/rds/tcp_listen.c:251
 rds_tcp_accept_worker+0x56/0x80 net/rds/tcp.c:525
 process_one_work+0xa05/0x17a0 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace 424f0561ef9bfe17 ]---
RIP: 0010:__list_del_entry_valid+0x85/0xf5 lib/list_debug.c:51
Code: 0f 84 e1 00 00 00 48 b8 22 01 00 00 00 00 ad de 49 39 c4 0f 84 e2 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 75 53 49 8b 14 24 4c 39 f2 0f 85 99 00 00 00 49 8d 7d
RSP: 0018:ffffc90001b27af0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff888020040c60 RCX: ffffffff81a1dda6
RDX: 0000000000000000 RSI: ffffffff81a1dba1 RDI: ffff888020040c68
RBP: ffffc90001b27b08 R08: ffff88809f18e280 R09: fffff52000364f51
R10: fffff52000364f50 R11: 0000000000000003 R12: 0000000000000000
R13: 0000000000000000 R14: ffff888020040c60 R15: ffff888020040c68
FS:  0000000000000000(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f78a44de000 CR3: 000000008c993000 CR4: 00000000001426e0
DR0: 0000000000000000 DR1: 0000000000006920 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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