Bug 762096 (GLUSTER-364)

Initial observation showed that

this->private was NULL 

(gdb) p *table 
cannot access memory 0x0

Seems like we need a NULL check. 

By looking at logs it seems that the fini was trigged as glusterfs got
a sigterm while it was waiting on "waitpid" inside "fuse_mnt_add_mount"

Can you please place the core file in /share/bugzilla/<bugid>?

I can't this was reproduced on Storage Platform and the machine i am using is a laptop with no connectivity.. to internet.. I tried getting as many logs as 
i could.

Observed a segfault while testing on "Storage Platform"

Follwoing the gdb backtrace. 

(gdb) 
#0  0x00000038bc4087a0 in pthread_mutex_destroy () from /lib64/libpthread.so.0
#1  0x00007f7483fae5d1 in fini (this=0x1ba6d60) at io-cache.c:1351
#2  0x0000000000402d1f in cleanup_and_exit (signum=<value optimized out>) at glusterfsd.c:950
#3  <signal handler called>
#4  0x00000038bc40ea2b in waitpid () from /lib64/libpthread.so.0
#5  0x00007f7483da6c11 in fuse_mnt_add_mount (fsname=0x1ba01e0 "/etc/glusterfs/test.vol", mnt=0x1ba81e0 "/nfs/test", type=0x7f7483da8d24 "fuse.glusterfs", 
    opts=0x7f7483da7df8 "allow_other,default_permissions,max_read=131072", progname=<value optimized out>) at ../../../../contrib/fuse-lib/mount.c:153
#6  0x00007f7483da733d in fuse_mount_sys (mnt_param=<value optimized out>, fsname=<value optimized out>, mountpoint=<value optimized out>) at ../../../../contrib/fuse-lib/mount.c:553
#7  gf_fuse_mount (mnt_param=<value optimized out>, fsname=<value optimized out>, mountpoint=<value optimized out>) at ../../../../contrib/fuse-lib/mount.c:582
#8  0x00007f7483d99fab in init (this_xl=0x1ba1520) at fuse-bridge.c:3391
#9  0x00000038bbc1408b in xlator_init (xl=0x1ba1520) at xlator.c:940
#10 0x00000038bbc14121 in xlator_init_rec (xl=<value optimized out>) at xlator.c:833
#11 xlator_tree_init (xl=<value optimized out>) at xlator.c:871
#12 0x00000000004033cc in _xlator_graph_init (xl=<value optimized out>) at glusterfsd.c:581
#13 glusterfs_graph_init (xl=<value optimized out>) at glusterfsd.c:631
#14 0x0000000000404038 in main (argc=<value optimized out>, argv=<value optimized out>) at glusterfsd.c:1344
(gdb) (gdb) (gdb) quit

Everyone, 

whats going on with this bug, is it still viable?. As i don't have much information other than the backtrace and client log file.

which translator's this->private was NULL? The information contained is very less to fix the bug. It does not point to whether io-cache is the culprit.

There are two things in bug

one is waitpid() code is from fuse_mnt_add_sys which is waiting to mount not sure why it is waiting long enough here. 

Now i am not sure how it is reproducible. If i can remember "this->private" is
from the fini which is called for io-cache right with SIGTERM (cleanup_and_exit).

PATCH: http://patches.gluster.com/patch/2618 in master (Added null checks in "fini")

PATCH: http://patches.gluster.com/patch/2619 in release-2.0 (Add null pointer checks in "fini")

Verifed with 2.0.10rc1