Re: general protection fault in wb_timer_fn

[Christoph Hellwig]

On Wed, Sep 15, 2021 at 09:49:49AM +0800, Hao Sun wrote:
> console output: https://paste.ubuntu.com/p/5qHqPXWmCQ/
> kernel config: https://paste.ubuntu.com/p/VsVbFh9ZpQ/
> C reproducer: https://paste.ubuntu.com/p/yrYsn4zpcn/
> Syzlang reproducer: https://paste.ubuntu.com/p/bCWyNyHncJ/
> 
> Just tried the C reproducer on the latest Linux kernel (6880fa6c5660
> Linux 5.15-rc1).
> The reproducer still crashed the kernel but with a different backtrace.

Well, that trace looks very much like an issue in the MM truncate code.
Adding the linux-mm list.

> 
> IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
> IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
> Bluetooth: hci0: command 0x0409 tx timeout
> ------------[ cut here ]------------
> kernel BUG at fs/buffer.c:1510!
> invalid opcode: 0000 [#1] PREEMPT SMP
> CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.14.0+ #15
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> Workqueue: events delayed_fput
> RIP: 0010:block_invalidatepage+0x27f/0x2a0 -origin/fs/buffer.c:1510
> Code: ff ff e8 b4 07 d7 ff b9 02 00 00 00 be 02 00 00 00 4c 89 ff 48
> c7 c2 40 4e 25 84 e8 2b c2 c4 02 e9 c9 fe ff ff e8 91 07 d7 ff <0f> 0b
> e8 8a 07 d7 ff 0f 0b e8 83 07 d7 ff 48 8d 5d ff e9 57 ff ff
> RSP: 0018:ffffc9000065bb60 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffffea0000670000 RCX: 0000000000000000
> RDX: ffff8880097fa240 RSI: ffffffff81608a9f RDI: ffffea0000670000
> RBP: ffffea0000670000 R08: 0000000000000001 R09: 0000000000000000
> R10: ffffc9000065b9f8 R11: 0000000000000003 R12: ffffffff81608820
> R13: ffffc9000065bc68 R14: 0000000000000000 R15: ffffc9000065bbf0
> FS:  0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f4aef93fb08 CR3: 0000000108cf2000 CR4: 0000000000750ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
>  do_invalidatepage -origin/mm/truncate.c:157 [inline]
>  truncate_cleanup_page+0x15c/0x280 -origin/mm/truncate.c:176
>  truncate_inode_pages_range+0x169/0xc30 -origin/mm/truncate.c:325
>  kill_bdev.isra.29+0x28/0x30
>  blkdev_flush_mapping+0x4c/0x130 -origin/block/bdev.c:658
>  blkdev_put_whole+0x54/0x60 -origin/block/bdev.c:689
>  blkdev_put+0x6f/0x210 -origin/block/bdev.c:953
>  blkdev_close+0x25/0x30 -origin/block/fops.c:459
>  __fput+0xdf/0x380 -origin/fs/file_table.c:280
>  delayed_fput+0x25/0x40 -origin/fs/file_table.c:308
>  process_one_work+0x359/0x850 -origin/kernel/workqueue.c:2297
>  worker_thread+0x41/0x4d0 -origin/kernel/workqueue.c:2444
>  kthread+0x178/0x1b0 -origin/kernel/kthread.c:319
>  ret_from_fork+0x1f/0x30 -origin/arch/x86/entry/entry_64.S:295
> Modules linked in:
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> ---[ end trace 9dbb8f58f2109f10 ]---
> RIP: 0010:block_invalidatepage+0x27f/0x2a0 -origin/fs/buffer.c:1510
> Code: ff ff e8 b4 07 d7 ff b9 02 00 00 00 be 02 00 00 00 4c 89 ff 48
> c7 c2 40 4e 25 84 e8 2b c2 c4 02 e9 c9 fe ff ff e8 91 07 d7 ff <0f> 0b
> e8 8a 07 d7 ff 0f 0b e8 83 07 d7 ff 48 8d 5d ff e9 57 ff ff
> RSP: 0018:ffffc9000065bb60 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffffea0000670000 RCX: 0000000000000000
> RDX: ffff8880097fa240 RSI: ffffffff81608a9f RDI: ffffea0000670000
> RBP: ffffea0000670000 R08: 0000000000000001 R09: 0000000000000000
> R10: ffffc9000065b9f8 R11: 0000000000000003 R12: ffffffff81608820
> R13: ffffc9000065bc68 R14: 0000000000000000 R15: ffffc9000065bbf0
> FS:  0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ff98674f000 CR3: 0000000106b2e000 CR4: 0000000000750ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
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