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Date:   Wed, 14 Oct 2020 16:53:08 +0200
From:   Jonas Zeiger <jonas.zeiger@talpidae.net>
To:     linux-nfs@vger.kernel.org
Subject: Re: Linux 5.9.0: NFS 4.1 with cachefilesd: Assertion failed (100%
 CPU)
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Seems like this is already being worked on and has also been reported as:

https://bugzilla.kernel.org/show_bug.cgi?id=208883

On 2020-10-14 15:07, Jonas Zeiger wrote:
> Hi all,
> 
> I experience failed assertions on an x86_64 KVM virtual machine (VirtIO devices) when accessing files on NFS 4 shares while having cachefilesd (0.10.7) running.
> 
> Good kernel: 4.14.49
> Bad kernels: 5.8.14, 5.9.0
> 
> The machine is rendered unusable (100% CPU) and requires a hard-reset.
> 
> This is the console error report captured via serial console:
> 
> CacheFiles: 
> CacheFiles: Assertion failed
> invalid opcode: 0000 [#1]
> CPU: 0 PID: 4215 Comm: git Not tainted 5.9.0vzlinux #3
> RIP: 0010:cachefiles_read_or_alloc_pages+0x9e/0x5cf
> Code: ff 0f 0b 49 8b 46 30 48 8b 40 70 48 83 78 20 00 75 1a 48 c7 c7 20 fc e8 81 e8 cf 7a e7 ff 48 c7 c7 30 fc e8 81 e8 c3 7a e7 ff <0f> 0b 49 8b 46 28 ba 0c 00 00 00 c6 44 24 40 00 c6 44 24 41 00 c7
> RSP: 0000:ffffc900015cba98 EFLAGS: 00010292
> RAX: 000000000000001c RBX: ffffc900015cbc04 RCX: 0000000000000027
> RDX: 0000000000000001 RSI: 0000000000000001 RDI: ffffffff82039340
> RBP: ffff88803c3469c0 R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000001e88c R11: 000000000000003c R12: ffffc900015cbd70
> R13: ffff88803c3469c0 R14: ffff88802e2d2fd0 R15: ffff88802bf27000
> FS:  00007feea1027fc0(0000) GS:ffffffff82030000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007feea1036000 CR3: 000000002bcbd005 CR4: 00000000001706b0
> Call Trace:
>  ? nfs_access_add_cache+0x140/0x1c5
>  ? slab_free_freelist_hook+0x45/0xc4
>  ? slab_pre_alloc_hook.isra.81+0x26/0x37
>  ? fscache_run_op.isra.13+0x57/0x69
>  __fscache_read_or_alloc_pages+0x1a6/0x1f2
>  __nfs_readpages_from_fscache+0x51/0xa9
>  nfs_readpages+0x111/0x133
>  ? get_page_from_freelist+0x734/0x8a1
>  read_pages+0x8c/0x102
>  ? __alloc_pages_nodemask+0xd4/0x122
>  ? page_cache_readahead_unbounded+0xce/0x17d
>  page_cache_readahead_unbounded+0xce/0x17d
>  filemap_fault+0x1f9/0x3d8
>  __do_fault+0x44/0x63
>  handle_mm_fault+0x70e/0xad3
>  exc_page_fault+0x1f0/0x311
>  ? asm_exc_page_fault+0x5/0x20
>  asm_exc_page_fault+0x1b/0x20
> RIP: 0033:0x7feea0991bef
> Code: 41 c7 45 00 1d 00 00 00 e9 1e f8 ff ff 41 8b 55 08 85 d2 0f 84 72 07 00 00 83 fb 0f 0f 87 37 14 00 00 85 ed 0f 84 83 f5 ff ff <41> 0f b6 34 24 89 d9 8d 45 ff 49 8d 7c 24 01 48 d3 e6 8d 4b 08 4c
> RSP: 002b:00007fffbb7d5240 EFLAGS: 00010202
> RAX: 00007feea0991bd2 RBX: 0000000000000000 RCX: 00000000000000d0
> RDX: 0000000000000001 RSI: 000055d7e1bf9c10 RDI: 00007fffbb7d52a0
> RBP: 00000000000000d0 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 00007fffbb7d5390 R12: 00007feea1036000
> R13: 000055d7e1bf9900 R14: 00007fffbb7d5570 R15: 0000000000000000
> ---[ end trace cad4b4a2dd601cdd ]---
> RIP: 0010:cachefiles_read_or_alloc_pages+0x9e/0x5cf
> Code: ff 0f 0b 49 8b 46 30 48 8b 40 70 48 83 78 20 00 75 1a 48 c7 c7 20 fc e8 81 e8 cf 7a e7 ff 48 c7 c7 30 fc e8 81 e8 c3 7a e7 ff <0f> 0b 49 8b 46 28 ba 0c 00 00 00 c6 44 24 40 00 c6 44 24 41 00 c7
> RSP: 0000:ffffc900015cba98 EFLAGS: 00010292
> RAX: 000000000000001c RBX: ffffc900015cbc04 RCX: 0000000000000027
> RDX: 0000000000000001 RSI: 0000000000000001 RDI: ffffffff82039340
> RBP: ffff88803c3469c0 R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000001e88c R11: 000000000000003c R12: ffffc900015cbd70
> R13: ffff88803c3469c0 R14: ffff88802e2d2fd0 R15: ffff88802bf27000
> FS:  00007feea1027fc0(0000) GS:ffffffff82030000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007feea1036000 CR3: 000000002bcbd005 CR4: 00000000001706b0
> Kernel panic - not syncing: Fatal exception
> Kernel Offset: disabled
> ---[ end Kernel panic - not syncing: Fatal exception ]---
> 
> Feel free to ask for further info or testing patches.
> 
> Thank you!
> 
> Regards,
> Jonas Zeiger
> 
> 
> Ps: I found this mail https://lkml.org/lkml/2020/3/20/399 describing a similar issue, but it may be unrelated.