vboxsf module crashes during high load

[sleepycal]

I was able to reproduce a vboxsf crash twice whilst running "npm install" on a shared directory, which triggers a lot of different file activity (create/link/read/syay etc).

My guest machine is;
Linux vagrant-ubuntu-trusty-64 3.13.0-49-generic #83-Ubuntu SMP Fri Apr 10 20:11:33 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux Ubuntu 14.04.2 LTS

My host machine is;
VirtualBox 4.3.24 on OS X Yosemite 10.10.2

[sleepycal]

Sorry, formatting got a little crazy

[ 1563.157119] BUG: unable to handle kernel NULL pointer dereference at           (null)
[ 1563.157903] IP: [<          (null)>]           (null)
[ 1563.158405] PGD 3e2ae067 PUD 3e55f067 PMD 0
[ 1563.158816] Oops: 0010 [#1] SMP
[ 1563.159151] Modules linked in: vboxsf(OX) nfsd auth_rpcgss nfs_acl nfs lockd sunrpc fscache dm_crypt ppdev serio_raw parport_pc parport video vboxguest(OX) ahci e1000 psmouse libahci
[ 1563.160328] CPU: 1 PID: 5195 Comm: npm Tainted: G           OX 3.13.0-49-generic #83-Ubuntu
[ 1563.160328] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 1563.160328] task: ffff88003732b000 ti: ffff88003e6e6000 task.ti: ffff88003e6e6000
[ 1563.160328] RIP: 0010:[<0000000000000000>]  [<          (null)>]           (null)
[ 1563.160328] RSP: 0018:ffff88003e6e7c58  EFLAGS: 00010246
[ 1563.160328] RAX: ffffffffa01fe140 RBX: ffff88000e5c303b RCX: 000000005541054c
[ 1563.160328] RDX: 0000000000000009 RSI: ffff88003e6e7dd0 RDI: ffff88002f38a180
[ 1563.160328] RBP: ffff88003e6e7cf8 R08: 000000005541054c R09: 0000000000000001
[ 1563.160328] R10: ffffea0000f7ef00 R11: ffffffffa00a4b4a R12: ffff88003732b000
[ 1563.160328] R13: 0000000000000000 R14: ffff88002f38a180 R15: ffff88003e6e7dd0
[ 1563.160328] FS:  00002ba45decf700(0000) GS:ffff880041500000(0000) knlGS:0000000000000000
[ 1563.160328] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 1563.160328] CR2: 0000000000000000 CR3: 000000003e582000 CR4: 00000000000006e0
[ 1563.160328] Stack:
[ 1563.160328]  ffffffff811cb049 ffffffff812d71cc ffff88003e6e7c90 ffff88003732b000
[ 1563.160328]  ffff88003e6e7df0 ffff88003732b000 ffff88003e6e7cc0 ffff88003d84b6d0
[ 1563.160328]  ffffffff811c8f88 ffff8800370e33e0 ffff88002f38a180 0000000c8bd82fae
[ 1563.160328] Call Trace:
[ 1563.160328]  [<ffffffff811cb049>] ? link_path_walk+0x549/0x870
[ 1563.160328]  [<ffffffff812d71cc>] ? security_inode_permission+0x1c/0x30
[ 1563.160328]  [<ffffffff811c8f88>] ? inode_permission+0x18/0x50
[ 1563.160328]  [<ffffffff811cb3cb>] path_lookupat+0x5b/0x790
[ 1563.160328]  [<ffffffff811d4ac4>] ? dput+0x24/0x180
[ 1563.160328]  [<ffffffff811d6f20>] ? __d_lookup+0x120/0x160
[ 1563.160328]  [<ffffffff811a3004>] ? kmem_cache_alloc+0x84/0x1e0
[ 1563.160328]  [<ffffffff811cde8f>] ? getname_flags+0x4f/0x190
[ 1563.160328]  [<ffffffff811cbb2b>] filename_lookup+0x2b/0xc0
[ 1563.160328]  [<ffffffff811ceb64>] user_path_at_empty+0x54/0x90
[ 1563.160328]  [<ffffffff811cebb1>] user_path_at+0x11/0x20
[ 1563.160328]  [<ffffffff811c2d40>] vfs_fstatat+0x50/0xa0
[ 1563.160328]  [<ffffffff811a218b>] ? kmem_cache_free+0xab/0x1e0
[ 1563.160328]  [<ffffffff811c3222>] SYSC_newlstat+0x22/0x40
[ 1563.160328]  [<ffffffff811ce07c>] ? user_path_create+0x4c/0x60
[ 1563.160328]  [<ffffffff811cf2b8>] ? SyS_mkdir+0x38/0xe0
[ 1563.160328]  [<ffffffff811c343e>] SyS_newlstat+0xe/0x10
[ 1563.160328]  [<ffffffff8173263d>] system_call_fastpath+0x1a/0x1f
[ 1563.160328] Code:  Bad RIP value.
[ 1563.160328] RIP  [<          (null)>]           (null)
[ 1563.160328]  RSP <ffff88003e6e7c58>
[ 1563.160328] CR2: 0000000000000000
[ 1563.184076] ---[ end trace 09765f94806f2c72 ]---