[  122.624102] EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null)
[  148.385076] ------------[ cut here ]------------
[  148.389711] kernel BUG at /home/davehans/linux.git/fs/ext4/inode.c:2377!
[  148.396515] invalid opcode: 0000 [#1] SMP 
[  148.400669] CPU: 126 PID: 4072 Comm: racewrite_threa Not tainted 3.15.0-rc2+ #390
[  148.408281] Hardware name: FUJITSU-SV PRIMEQUEST 1800E2/SB, BIOS PRIMEQUEST 1000 Series BIOS Version 1.24 09/14/2011
[  148.419057] task: ffff883ff1424500 ti: ffff883fec320000 task.ti: ffff883fec320000
[  148.426668] RIP: 0010:[<ffffffff81204810>]  [<ffffffff81204810>] mpage_prepare_extent_to_map+0x320/0x330
[  148.436301] RSP: 0018:ffff883fec321c68  EFLAGS: 00010246
[  148.441690] RAX: 000000000000002e RBX: ffff883fec321dc8 RCX: ffff883ff0641738
[  148.448941] RDX: 4bfffc000002003d RSI: 0000000000000167 RDI: ffffffff819c1ce8
[  148.456190] RBP: ffff883fec321d48 R08: ffffea027ffe3fc0 R09: 0000000000000001
[  148.463440] R10: 0000000000000000 R11: 0000000000000220 R12: 7fffffffffffffff
[  148.470691] R13: 000000000000002e R14: ffff883fec321ca8 R15: ffff883fec321ca8
[  148.477943] FS:  00007f8cb8982700(0000) GS:ffff889fffc00000(0000) knlGS:0000000000000000
[  148.486187] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  148.492021] CR2: 00007f8cf7a2f000 CR3: 0000005ff1b4b000 CR4: 00000000000007e0
[  148.499271] Stack:
[  148.501304]  ffffea027ffe3fc0 ffff883fec321ca8 ffff883ff0641738 0000000000000000
[  148.508813]  0000000000000000 0000000000000001 0000000000000000 ffffea027ffe3fc0
[  148.516324]  0000000000000007 0000000000000286 ffffffff81056f26 ffff885ff1ec3800
[  148.523836] Call Trace:
[  148.526319]  [<ffffffff81056f26>] ? current_fs_time+0x16/0x60
[  148.532151]  [<ffffffff81233fcc>] ? __ext4_journal_start_sb+0x7c/0x120
[  148.538772]  [<ffffffff8120af6b>] ? ext4_writepages+0x44b/0xce0
[  148.544779]  [<ffffffff8120afa4>] ext4_writepages+0x484/0xce0
[  148.550617]  [<ffffffff81123933>] do_writepages+0x23/0x40
[  148.556093]  [<ffffffff811165f9>] __filemap_fdatawrite_range+0x59/0x60
[  148.562717]  [<ffffffff8111b3f5>] SyS_fadvise64_64+0x265/0x270
[  148.568635]  [<ffffffff8111b40e>] SyS_fadvise64+0xe/0x10
[  148.574035]  [<ffffffff816d8a29>] system_call_fastpath+0x16/0x1b
[  148.580119] Code: ff e9 6d ff ff ff 48 8d bd 48 ff ff ff e8 b9 20 f2 ff e9 31 ff ff ff 48 8b 4b 08 8b 49 20 85 c9 0f 85 ee fd ff ff 31 c0 eb b3 90 <0f> 0b 0f 0b 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90 
[  148.599293] RIP  [<ffffffff81204810>] mpage_prepare_extent_to_map+0x320/0x330
[  148.606540]  RSP <ffff883fec321c68>
[  148.610098] ---[ end trace ec598c40bf0d0723 ]---

                        mpd->next_page = page->index + 1;
                        /* Add all dirty buffers to mpd */
                        lblk = ((ext4_lblk_t)page->index) <<
                                (PAGE_CACHE_SHIFT - blkbits);
------------>           head = page_buffers(page); <-----------------------------------
                        err = mpage_process_page_bufs(mpd, head, head, lblk);
                        if (err <= 0)
                                goto out;
                        err = 0;
                        left--;
                }