[Gluster-devel] Possible problem introduced by http://review.gluster.org/15573

[Soumya Koduri]

On 10/21/2016 02:03 PM, Xavier Hernandez wrote:
> Hi Niels,
>
> On 21/10/16 10:03, Niels de Vos wrote:
>> On Fri, Oct 21, 2016 at 09:03:30AM +0200, Xavier Hernandez wrote:
>>> Hi,
>>>
>>> I've just tried Gluster 3.8.5 with Proxmox using gfapi and I
>>> consistently
>>> see a crash each time an attempt to connect to the volume is made.
>>
>> Thanks, that likely is the same bug as
>> https://bugzilla.redhat.com/1379241 .
>
> I'm not sure it's the same problem. The crash on my case happens always
> and immediately. When creating an image, the file is created but size is
> 0. The stack trace is quite different also.

Right. The issue reported in sug1379241 looks like the one we hit with 
client-io-threads enabled (already discussed in gluster-devel). 
Disabling that option may prevent the crash seen.

Thanks,
Soumya

>
> Xavi
>
>>
>> Satheesaran, could you revert commit 7a50690 from the build that you
>> were testing, and see if that causes the problem to go away again? Let
>> me know of you want me to provide RPMs for testing.
>>
>> Niels
>>
>>>
>>> The backtrace of the crash shows this:
>>>
>>> #0  pthread_spin_lock () at
>>> ../nptl/sysdeps/x86_64/pthread_spin_lock.S:24
>>> #1  0x00007fe5345776a5 in fd_unref (fd=0x7fe523f7205c) at fd.c:553
>>> #2  0x00007fe53482ba18 in glfs_io_async_cbk (op_ret=<optimized out>,
>>> op_errno=0, frame=<optimized out>, cookie=0x7fe526c67040,
>>> iovec=iovec at entry=0x0, count=count at entry=0)
>>>     at glfs-fops.c:839
>>> #3  0x00007fe53482beed in glfs_fsync_async_cbk (frame=<optimized out>,
>>> cookie=<optimized out>, this=<optimized out>, op_ret=<optimized out>,
>>> op_errno=<optimized out>,
>>>     prebuf=<optimized out>, postbuf=0x7fe5217fe890, xdata=0x0) at
>>> glfs-fops.c:1382
>>> #4  0x00007fe520be2eb7 in ?? () from
>>> /usr/lib/x86_64-linux-gnu/glusterfs/3.8.5/xlator/debug/io-stats.so
>>> #5  0x00007fe5345d118a in default_fsync_cbk (frame=0x7fe52ceef3ac,
>>> cookie=0x560ef95398e8, this=0x8, op_ret=0, op_errno=0, prebuf=0x1,
>>> postbuf=0x7fe5217fe890, xdata=0x0) at defaults.c:1508
>>> #6  0x00007fe5345d118a in default_fsync_cbk (frame=0x7fe52ceef204,
>>> cookie=0x560ef95398e8, this=0x8, op_ret=0, op_errno=0, prebuf=0x1,
>>> postbuf=0x7fe5217fe890, xdata=0x0) at defaults.c:1508
>>> #7  0x00007fe525f78219 in dht_fsync_cbk (frame=0x7fe52ceef2d8,
>>> cookie=0x560ef95398e8, this=0x0, op_ret=0, op_errno=0,
>>> prebuf=0x7fe5217fe820, postbuf=0x7fe5217fe890, xdata=0x0)
>>>     at dht-inode-read.c:873
>>> #8  0x00007fe5261bbc7f in client3_3_fsync_cbk (req=0x7fe525f78030
>>> <dht_fsync_cbk>, iov=0x7fe526c61040, count=8, myframe=0x7fe52ceef130) at
>>> client-rpc-fops.c:975
>>> #9  0x00007fe5343201f0 in rpc_clnt_handle_reply (clnt=0x18,
>>> clnt at entry=0x7fe526fafac0, pollin=0x7fe526c3a1c0) at rpc-clnt.c:791
>>> #10 0x00007fe53432056c in rpc_clnt_notify (trans=<optimized out>,
>>> mydata=0x7fe526fafaf0, event=<optimized out>, data=0x7fe526c3a1c0) at
>>> rpc-clnt.c:962
>>> #11 0x00007fe53431c8a3 in rpc_transport_notify (this=<optimized out>,
>>> event=<optimized out>, data=<optimized out>) at rpc-transport.c:541
>>> #12 0x00007fe5283e8d96 in socket_event_poll_in (this=0x7fe526c69440) at
>>> socket.c:2267
>>> #13 0x00007fe5283eaf37 in socket_event_handler (fd=<optimized out>,
>>> idx=5,
>>> data=0x7fe526c69440, poll_in=1, poll_out=0, poll_err=0) at socket.c:2397
>>> #14 0x00007fe5345ab3f6 in event_dispatch_epoll_handler
>>> (event=0x7fe5217fecc0, event_pool=0x7fe526ca2040) at event-epoll.c:571
>>> #15 event_dispatch_epoll_worker (data=0x7fe527c0f0c0) at
>>> event-epoll.c:674
>>> #16 0x00007fe5324140a4 in start_thread (arg=0x7fe5217ff700) at
>>> pthread_create.c:309
>>> #17 0x00007fe53214962d in clone () at
>>> ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
>>>
>>> The fd being unreferenced contains this:
>>>
>>> (gdb) print *fd
>>> $6 = {
>>>   pid = 97649,
>>>   flags = 2,
>>>   refcount = 0,
>>>   inode_list = {
>>>     next = 0x7fe523f7206c,
>>>     prev = 0x7fe523f7206c
>>>   },
>>>   inode = 0x0,
>>>   lock = {
>>>     spinlock = 1,
>>>     mutex = {
>>>       __data = {
>>>         __lock = 1,
>>>         __count = 0,
>>>         __owner = 0,
>>>         __nusers = 0,
>>>         __kind = 0,
>>>         __spins = 0,
>>>         __elision = 0,
>>>         __list = {
>>>           __prev = 0x0,
>>>           __next = 0x0
>>>         }
>>>       },
>>>       __size = "\001", '\000' <repeats 38 times>,
>>>       __align = 1
>>>     }
>>>   },
>>>   _ctx = 0x7fe52ec31c40,
>>>   xl_count = 11,
>>>   lk_ctx = 0x7fe526c126a0,
>>>   anonymous = _gf_false
>>> }
>>>
>>> fd->inode is NULL, explaining the cause of the crash. We also see that
>>> fd->refcount is already 0. So I'm wondering if this couldn't be an extra
>>> fd_unref() introduced by that patch.
>>>
>>> The crash seems to happen immediately after a graph switch.
>>>
>>> Xavi