Description of problem:
I see that client process of my system crashed (HC setup) and it is due to write behind translator. 

bt from core dump:
========================
warning: core file may not match specified executable file.
Reading symbols from /usr/sbin/glusterfsd...Reading symbols from /usr/lib/debug/usr/sbin/glusterfsd.debug...done.
done.
Missing separate debuginfo for 
Try: yum --enablerepo='*debug*' install /usr/lib/debug/.build-id/5b/9ed38e31ce6bd04ecca183ad6d6ee05a4535d0
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `/usr/sbin/glusterfs --volfile-server=10.70.36.82 --volfile-server=10.70.36.83 -'.
Program terminated with signal 11, Segmentation fault.
#0  0x00007fa230684e5b in __wb_dump_requests (head=head@entry=0x7fa2100256b8, prefix=prefix@entry=0x7fa2354b9370 "xlator.performance.write-behind.wb_inode")
    at write-behind.c:2355
2355	                        gf_proc_dump_write ("offset", "%"PRId64,
Missing separate debuginfos, use: debuginfo-install glibc-2.17-157.el7_3.1.x86_64 keyutils-libs-1.5.8-3.el7.x86_64 krb5-libs-1.14.1-27.el7_3.x86_64 libcom_err-1.42.9-9.el7.x86_64 libgcc-4.8.5-11.el7.x86_64 libselinux-2.5-6.el7.x86_64 libuuid-2.23.2-33.el7.x86_64 openssl-libs-1.0.1e-60.el7.x86_64 pcre-8.32-15.el7_2.1.x86_64 zlib-1.2.7-17.el7.x86_64
(gdb) bt
#0  0x00007fa230684e5b in __wb_dump_requests (head=head@entry=0x7fa2100256b8, prefix=prefix@entry=0x7fa2354b9370 "xlator.performance.write-behind.wb_inode")
    at write-behind.c:2355
#1  0x00007fa23068510e in wb_inode_dump (this=<optimized out>, inode=0x7fa2281dc590) at write-behind.c:2424
#2  0x00007fa238f0b550 in inode_dump (inode=0x7fa2281dc590, prefix=0x7fa2354ba420 "xlator.mount.fuse.itable.active.2") at inode.c:2367
#3  0x00007fa238f0b78f in inode_table_dump (itable=0x7fa21400fa90, prefix=prefix@entry=0x7fa235ce5994 "xlator.mount.fuse.itable") at inode.c:2408
#4  0x00007fa235ccaa2b in fuse_itable_dump (this=<optimized out>) at fuse-bridge.c:5103
#5  0x00007fa238f25722 in gf_proc_dump_xlator_info (top=<optimized out>) at statedump.c:504
#6  0x00007fa238f25cb9 in gf_proc_dump_info (signum=signum@entry=10, ctx=0x7fa23ad83010) at statedump.c:830
#7  0x00007fa2393eec3e in glusterfs_sigwaiter (arg=<optimized out>) at glusterfsd.c:2069
#8  0x00007fa237d5adc5 in start_thread () from /lib64/libpthread.so.0
#9  0x00007fa23769f73d in clone () from /lib64/libc.so.6
(gdb) 


Version-Release number of selected component (if applicable):
glusterfs-3.8.4-11.el7rhgs.x86_64

How reproducible:


Steps to Reproduce:
1.
2.
3.

Actual results:
client process  crashes. Due to this crash, all my app vms residing on that node goes to paused state and the host is in non operational state.

Expected results:
client process should not crash.

Additional info:

#0  0x00007fa230684e5b in __wb_dump_requests (head=head@entry=0x7fa2100256b8, prefix=prefix@entry=0x7fa2354b9370 "xlator.performance.write-behind.wb_inode")
    at write-behind.c:2355
(gdb) p	req->stub
$7 = (call_stub_t *) 0x0


2355                            gf_proc_dump_write ("offset", "%"PRId64,                                                                                                │
   │2356                                                req->stub->args.offset);