FYI, we noticed the below changes on
git://kernel.ubuntu.com/sforshee/linux.git userns-mounts
commit 1d5ab0e98cf0282077fc1ac2b261d5237b26073e ("loop: Add loop filesystem")
+------------------------------------------+------------+------------+
| | 87cad79097 | 1d5ab0e98c |
+------------------------------------------+------------+------------+
| boot_successes | 12 | 0 |
| boot_failures | 0 | 12 |
| BUG:unable_to_handle_kernel | 0 | 12 |
| Oops | 0 | 12 |
| RIP:loopfs_sb_from_inode | 0 | 12 |
| Kernel_panic-not_syncing:Fatal_exception | 0 | 12 |
| backtrace:loop_add | 0 | 12 |
| backtrace:loop_init | 0 | 12 |
| backtrace:kernel_init_freeable | 0 | 12 |
+------------------------------------------+------------+------------+
[ 3.923208] Floppy drive(s): fd0 is 1.44M
[ 3.935689] FDC 0 is a S82078B
[ 3.973524] brd: module loaded
[ 3.980099] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 3.981035] IP: [<ffffffff816de9e0>] loopfs_sb_from_inode+0x23/0x29
[ 3.981035] PGD 0
[ 3.981035] Oops: 0000 [#1] SMP
[ 3.981035] Modules linked in:
[ 3.981035] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.3.0-rc1-00034-g1d5ab0e #413
[ 3.981035] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[ 3.981035] task: ffff8800130a0000 ti: ffff8800130a8000 task.ti: ffff8800130a8000
[ 3.981035] RIP: 0010:[<ffffffff816de9e0>] [<ffffffff816de9e0>] loopfs_sb_from_inode+0x23/0x29
[ 3.981035] RSP: 0018:ffff8800130abdc8 EFLAGS: 00010246
[ 3.981035] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff880013c0ce06
[ 3.981035] RDX: 0000000000000000 RSI: 0000000000700000 RDI: 0000000000000000
[ 3.981035] RBP: ffff8800130abdc8 R08: 00000000be164353 R09: 0000000000000006
[ 3.981035] R10: ffff8800130abc10 R11: 00000000001db1f8 R12: 0000000000000000
[ 3.981035] R13: ffff8800001cdce0 R14: ffff8800150f6618 R15: 0000000000700000
[ 3.981035] FS: 0000000000000000(0000) GS:ffff880013c00000(0000) knlGS:0000000000000000
[ 3.981035] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 3.981035] CR2: 0000000000000008 CR3: 000000000220f000 CR4: 00000000000006f0
[ 3.981035] Stack:
[ 3.981035] ffff8800130abe18 ffffffff816dea08 ffff8800150f6618 0000000000000000
[ 3.981035] 0000000000000000 ffff8800130abc10 0000000000000000 ffff8800001cdce0
[ 3.981035] ffff8800150f6618 ffff8800001cda68 ffff8800130abe60 ffffffff816dc9d2
[ 3.981035] Call Trace:
[ 3.981035] [<ffffffff816dea08>] loopfs_new_dev+0x22/0x1a0
[ 3.981035] [<ffffffff816dc9d2>] loop_add+0x270/0x2e5
[ 3.981035] [<ffffffff825df45e>] loop_init+0x10c/0x162
[ 3.981035] [<ffffffff825df352>] ? brd_init+0x128/0x128
[ 3.981035] [<ffffffff81000312>] do_one_initcall+0xe7/0x177
[ 3.981035] [<ffffffff825930ec>] kernel_init_freeable+0x1c2/0x24a
[ 3.981035] [<ffffffff81c0f989>] ? rest_init+0x140/0x140
[ 3.981035] [<ffffffff81c0f997>] kernel_init+0xe/0xd4
[ 3.981035] [<ffffffff81c1db2f>] ret_from_fork+0x3f/0x70
[ 3.981035] [<ffffffff81c0f989>] ? rest_init+0x140/0x140
[ 3.981035] Code: 41 5f 5d 49 8d 62 f8 c3 0f 1f 44 00 00 55 48 85 ff 48 89 e5 74 0e 48 8b 47 28 48 81 78 60 70 6f 6f 6c 74 0b 48 8b 05 18 e3 f7 01 <48> 8b 40 08 5d c3 0f 1f 44 00 00 55 48 89 e5 41 57 41 89 f7 41
[ 3.981035] RIP [<ffffffff816de9e0>] loopfs_sb_from_inode+0x23/0x29
[ 3.981035] RSP <ffff8800130abdc8>
[ 3.981035] CR2: 0000000000000008
[ 3.981035] ---[ end trace 58d15d1469c4ff12 ]---
[ 3.981035] Kernel panic - not syncing: Fatal exception
Thanks,
Ying Huang
Err, where the heck is a loop file system coming from?
On Fri, Nov 13, 2015 at 12:06:32AM -0800, Christoph Hellwig wrote:
> Err, where the heck is a loop file system coming from?
I've been working on code to let some regular filesystems be mounted in
user namespace containers, and loopfs is an idea I'm playing with to
allow those containers to allocate and use loop devices (since they
can't mknod and devtmpfs isn't namepace aware). I'm not sure how I ended
up with the kbuild bot testing this code though, my tree doesn't feed
into linux-next or anything.
Seth