running "mount -o loop" system hang

[dlan17]

it's a Gentoo Linux system, using kernel 4.1.6 (sys-kernel/gentoo-sources-4.1.6), zfs-0.6.4.2, zfs-kmod-0.6.4.2, spl-0.6.4.2.

while running: mount -o loop portage-20150827.squashfs /mnt/test, will trigger kernel panic

[ 87.743950] general protection fault: 0000 [#1] SMP
[ 87.751424] Modules linked in: nfsd pl2303 usbserial ppdev x86_pkg_temp_thermal dcdbas usb_skeleton coretemp kvm_intel kvm parport_pc pata_acpi xts aes_x86_64
sha256_genx
[ 87.860617] CPU: 1 PID: 2139 Comm: spl_kmem_cache/ Tainted: P O 4.1.6-gentoo #1
[ 87.871921] Hardware name: Dell Inc. OptiPlex 390/0M5DCD, BIOS A11 10/14/2013
[ 87.881926] task: ffff880063bfc3d0 ti: ffff880063518000 task.ti: ffff880063518000
[ 87.892317] RIP: 0010:[] [] list_del+0xb/0x2f
[ 87.902801] RSP: 0018:ffff88006351ba78 EFLAGS: 00010087
[ 87.910999] RAX: ffffffff82371d00 RBX: ffffea00018073a0 RCX: ffffffff82371d00
[ 87.920996] RDX: 6a5c4d26169234f4 RSI: 0000000000000000 RDI: ffffea00018073a0
[ 87.930988] RBP: ffff88006351ba78 R08: 0000000000000000 R09: 0000000000000000
[ 87.940983] R10: 000000000000068e R11: 0000000000000002 R12: ffffea0001807380
[ 87.950992] R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff82371c40
[ 87.960967] FS: 0000000000000000(0000) GS:ffff880079e40000(0000) knlGS:0000000000000000
[ 87.971929] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 87.980550] CR2: 00007fffea7d2e28 CR3: 000000000220b000 CR4: 00000000000406e0
[ 87.990525] Stack:
[ 87.995331] ffff88006351bac8 ffffffff81112e72 0000000000000000 0000000000000000
[ 88.005603] ffffffff82371d00 ffffffff82371c40 0000000000000000 ffff880079e5b140
[ 88.015863] ffffffff82371c40 0000000000000141 ffff88006351bb48 ffffffff81114e80
[ 88.026117] Call Trace:
[ 88.031367] [] __rmqueue_smallest+0x6d/0xb4
[ 88.040000] [] __rmqueue+0x2d/0x1fd
[ 88.047895] [] ? __alloc_pages_nodemask+0x16b/0x6c0
[ 88.057164] [] get_page_from_freelist+0x1df/0x57b
[ 88.066266] [] __alloc_pages_nodemask+0x16b/0x6c0
[ 88.075370] [] ? _raw_spin_unlock+0xe/0x10
[ 88.083835] [] ? slab_post_alloc_hook.isra.32+0x11/0x20
[ 88.093425] [] __vmalloc_node_range+0x13e/0x1bb
[ 88.102317] [] __vmalloc_node+0x2f/0x31
[ 88.110500] [] ? spl_vmalloc+0x35/0x58 [spl]
[ 88.119103] [] __vmalloc+0x20/0x22
[ 88.126828] [] spl_vmalloc+0x35/0x58 [spl]
[ 88.135224] [] spl_kmem_cache_set_move+0x2d5/0x826 [spl]
[ 88.144826] [] spl_kmem_cache_set_move+0x32f/0x826 [spl]
[ 88.154386] [] ? trace_hardirqs_off+0x9/0x20
[ 88.162923] [] taskq_cancel_id+0x2d7/0x4a0 [spl]
[ 88.171789] [] ? wake_up_state+0x12/0x12
[ 88.179919] [] ? taskq_cancel_id+0xed/0x4a0 [spl]
[ 88.188840] [] kthread+0xa5/0xad
[ 88.196289] [] ? put_cred_rcu+0x59/0xbc
[ 88.204331] [] ? __kthread_parkme+0x61/0x61
[ 88.212713] [] ret_from_fork+0x42/0x70
[ 88.220664] [] ? __kthread_parkme+0x61/0x61
[ 88.229043] Code: 65 ff 0d 9d 93 ef 7e 83 f8 01 4c 89 a3 18 c0 ff ff 5b 48 19 c0 41 5c 48 f7 d0 5d 48 83 e0 f2 c3 48 8b 47 08 55 48 8b 17 48 89 e5 <48> 89 42 08
48 89 10
[ 88.254124] RIP [] list_del+0xb/0x2f
[ 88.262035] RSP
[ 88.268176] ---[ end trace d6ba8b4288207052 ]---
[ 94.877265] general protection fault: 0000 [#2] SMP
[ 94.884897] Modules linked in: nfsd pl2303 usbserial ppdev x86_pkg_temp_thermal dcdbas usb_skeleton coretemp kvm_intel kvm parport_pc pata_acpi xts aes_x86_64
sha256_genx
[ 94.995063] CPU: 1 PID: 4026 Comm: irqbalance Tainted: P D O 4.1.6-gentoo #1
[ 95.006069] Hardware name: Dell Inc. OptiPlex 390/0M5DCD, BIOS A11 10/14/2013
[ 95.016228] task: ffff880066f27440 ti: ffff8800763ac000 task.ti: ffff8800763ac000
[ 95.026701] RIP: 0010:[] [] __slab_free+0x52/0x2b3
[ 95.037673] RSP: 0018:ffff8800763afbd8 EFLAGS: 00010246
[ 95.045874] RAX: 5a92828b05611adb RBX: ffff8800601cf320 RCX: ffffffff8113a27e
[ 95.055860] RDX: ffff8800601cf320 RSI: 5a92828b05611adb RDI: ffff880100106000
[ 95.065798] RBP: ffff8800763afc78 R08: 0000000000000000 R09: 5a92828b05611adb
[ 95.075691] R10: 20656c62616b7361 R11: 0000000000000206 R12: 5a92828b05611adb
[ 95.085515] R13: 0000000000000000 R14: ffff880100106000 R15: ffff880062d65810
[ 95.095335] FS: 00007f3213d82740(0000) GS:ffff880079e40000(0000) knlGS:0000000000000000
[ 95.106104] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 95.114526] CR2: 00007f3213dbd000 CR3: 0000000076425000 CR4: 00000000000406e0
[ 95.124337] Stack:
[ 95.129005] ffffffff8201abe5 ffffffff8201abe6 ffff8800763afc90 ffff88006287c000
[ 95.139115] ffff8800763afc58 ffffffff815134cf ffffffff8201abe5 ffff88006287b47d
[ 95.149218] ffff8800763afcd0 ffff000aff0a0000 0000000000000fbb ffff8800763afc60
[ 95.159324] Call Trace:
[ 95.164433] [] ? vsnprintf+0x8a/0x3b1
[ 95.172417] [] ? sync_mm_rss+0x42/0x74
[ 95.180462] [] ? anon_vma_free+0x3c/0x40
[ 95.188675] [] kmem_cache_free+0xeb/0x140
[ 95.196952] [] anon_vma_free+0x3c/0x40
[ 95.204937] [] __put_anon_vma+0x17/0x36
[ 95.213004] [] put_anon_vma+0x1e/0x22
[ 95.220880] [] unlink_anon_vmas+0xf4/0x144
[ 95.229188] [] free_pgtables+0x3e/0xcc
[ 95.237134] [] unmap_region+0xc8/0xec
[ 95.244983] [] ? vma_gap_callbacks_propagate+0x1b/0x33
[ 95.254314] [] ? vma_rb_erase+0x171/0x197
[ 95.262521] [] do_munmap+0x275/0x2ea
[ 95.270283] [] vm_munmap+0x45/0x5e
[ 95.277859] [] SyS_munmap+0x26/0x2f
[ 95.285515] [] system_call_fastpath+0x12/0x71
[ 95.294029] Code: 0d 21 00 74 15 4c 8d 45 88 e8 01 fe ff ff 48 85 c0 49 89 c5 0f 84 63 02 00 00 4d 85 ed 74 0c 48 8b 75 88 4c 89 ef e8 1b 7e 9f 00 <49> 8b 44 24
18 4d 8b
[ 95.319068] RIP [] __slab_free+0x52/0x2b3
[ 95.327427] RSP
[ 95.333626] ---[ end trace d6ba8b4288207053 ]---

[kernelOfTruth]

#3651 Fix Linux 4.1 compat regarding loop device on ZFS

[drescherjm]

Use the 9999 git ebuilds or wait for 0.6.5.

[behlendorf]

Right, thanks for filing this but as mentioned it was addressed by #3651 so I'm closing this as a duplicate. Either of the proposed solutions will resolve the issue.