On Fri, Jun 23, 2006 at 03:19:52AM +0300, Anton Kornev wrote:
Anton,
It appears that you found a bug in the gnbd code. I have it on my todo list,
and I'll get to it as soon as possible. Frankly, I'm really suprised that this
hasn't come up earlier. The issue is that once a part of a request has been
send to the server, either the whole request must be sent or connection must
be dropped. In some cases, such as when the server is non-responsive, but still
has an open socket, it is necessary to send a signal break out of the socket
transfer and then shutdown the socket. In your case, you simply want the process
that is in the middle of the transfer to die. In this case, the appropriate
response is to finish sending the IO, and then pass the signal on. I need to
look though the code and make sure that I'm doing the appropriate thing for
all circumstances.
-Ben
> David,
>
> Thanks a lot for your comments.
> Actually it sounds rather strange for me.
>
> I tried to grep the /var/log/messages log with "gnbd" word and found that
> there are also
> other messages like this even on the working host with no GFS problems.
>
> bash-3.00# grep gnbd /var/log/messages
> Jun 19 08:16:20 node1 kernel: gnbd (pid 25756: alogc.pl) got signal 9
> Jun 19 08:16:20 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 19 08:16:20 node1 kernel: gnbd (pid 25756: alogc.pl) got signal 15
> Jun 19 08:16:20 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 19 09:51:59 node1 kernel: gnbd (pid 26259: find) got signal 9
> Jun 19 09:51:59 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 19 10:06:39 node1 kernel: gnbd (pid 313: alogc.pl) got signal 9
> Jun 19 10:06:39 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 19 10:06:39 node1 kernel: gnbd (pid 313: alogc.pl) got signal 15
> Jun 19 10:06:39 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 19 12:51:12 node1 kernel: gnbd (pid 19463: vi) got signal 1
> Jun 19 12:51:12 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 20 14:48:16 node1 kernel: gnbd (pid 20238: alogc.pl) got signal 9
> Jun 20 14:48:16 node1 kernel: gnbd0: Send control failed (result -4)
> Jun 20 14:48:16 node1 kernel: gnbd (pid 20238: alogc.pl) got signal 15
> Jun 20 14:48:16 node1 kernel: gnbd0: Send control failed (result -4)
>
> I tried to check gnbd-kernel sources (latest available SRPM - not CVS
> version)
> and I found that the first message (gnbd ... got signal) is produced by
> the
> sock_xmit() function with the such a piece of code:
>
> if (signal_pending(current)) {
> siginfo_t info;
> spin_lock_irqsave(¤t->sighand->siglock,
> flags);
> printk(KERN_WARNING "gnbd (pid %d: %s) got signal
> %d\n",
> current->pid, current->comm,
> dequeue_signal(current, ¤t->blocked,
> &info));
> spin_unlock_irqrestore(¤t->sighand->siglock,
> flags);
> result = -EINTR;
> break;
> }
>
> And the second message is generated inside the gnbd_send_req() by the code
>
> result = sock_xmit(sock, 1, &request, sizeof(request),
> (gnbd_cmd(req) == GNBD_CMD_WRITE)? MSG_MORE: 0);
> if (result < 0) {
> printk(KERN_ERR "%s: Send control failed (result %d)\n",
> dev->disk->disk_name, result);
> goto error_out;
> }
>
> So at the first glance it seems like a normal messages from gnbd - if
> there is signal received during sock_xmit - don't send anyting and return
> -EINTR.
>
> I am not sure that it might be a problem but I take a look on the
> sock_xmit() code and
> there are at least two things that seems strange for me.
>
> 1. There is an inconsistancy between comment and code:
>
> /* Allow interception of SIGKILL only
> * Don't allow other signals to interrupt the transmission */
> spin_lock_irqsave(¤t->sighand->siglock, flags);
> oldset = current->blocked;
> sigfillset(¤t->blocked);
> sigdelsetmask(¤t->blocked, sigmask(SIGKILL) |
> sigmask(SIGTERM) |
> sigmask(SIGHUP));
> recalc_sigpending();
> spin_unlock_irqrestore(¤t->sighand->siglock, flags);
>
> So, inside the comment there is a suggestion that only SIGKILL can
> interrupt the transmission but the real mask is for KILL/TERM/HUP signals
> (btw: in my case it is a SIGTERM who locks everything).
>
> 2. There are two blocks of code following each other
>
> if (send)
> result = sock_sendmsg(sock, &msg, size);
> else
> result = sock_recvmsg(sock, &msg, size, 0);
>
> if (signal_pending(current)) {
> siginfo_t info;
> spin_lock_irqsave(¤t->sighand->siglock,
> flags);
> printk(KERN_WARNING "gnbd (pid %d: %s) got signal
> %d\n",
> current->pid, current->comm,
> dequeue_signal(current, ¤t->blocked,
> &info));
> spin_unlock_irqrestore(¤t->sighand->siglock,
> flags);
> result = -EINTR;
> break;
> }
>
> Why do we need to return -EINTR as a result if we have already done the
> real sock_sendmsg() / sock_recvmsg()? What if the real transmission was
> okay and real result has no mistake?
>
> I am not a kernel developer and I haven't spent a lot of time on the
> issue, so it might make no sense at all.
>
> Please, let me know what do you think about it?
>
> On 6/21/06, David Teigland <[1]teigland@xxxxxxxxxx> wrote:
>
> On Fri, Jun 16, 2006 at 06:37:14PM +0300, Anton Kornev wrote:
> > gnbd (pid 5836: alogc.pl) got signal 9
> > gnbd0: Send control failed (result -4)
> > gnbd (pid 5836: alogc.pl) got signal 15
> > gnbd0: Send control failed (result -4)
>
> This and the fact that a number of processes appear to be blocked in the
> i/o path seem to point at gnbd as the hold-up.
>
> Dave
>
> > 51 D wait_on_buffer pdflush
> > 5771 D lock_page lock_dlm1
> > 5776 D - gfs_logd
> > 5777 D - gfs_quotad
> > 5778 D - gfs_inoded
> > 5892 D - httpd
> > 5895 D glock_wait_internal httpd
> > 5896 D glock_wait_internal httpd
> > 5897 D glock_wait_internal httpd
> > 5911 D glock_wait_internal httpd
> > 5915 D wait_on_buffer httpd
> > 5930 D wait_on_buffer sh
>
> > pdflush D ffffffff8014aabc
> 0 51 6 53 50
> > (L-TLB)
> > 00000100dfc3dc78 0000000000000046 000001011bd3e980 000001010fc11f00
> > 0000000000000216 ffffffffa0042916 000001011aca60c0
> 0000000000000008
> > 000001011fdef7f0 0000000000000dfa
> > Call Trace:<ffffffffa0042916>{:dm_mod:dm_request+396}
> > <ffffffff8014aabc>{keventd_create_kthread+0}
> > <ffffffff803053ef>{io_schedule+38}
> > <ffffffff80178c4c>{__wait_on_buffer+125}
> > <ffffffff80178ad2>{bh_wake_function+0}
> > <ffffffff80178ad2>{bh_wake_function+0}
> > <ffffffffa0235c5d>{:gfs:gfs_logbh_wait+49}
> > <ffffffffa024a6a6>{:gfs:disk_commit+794}
> > <ffffffffa024a877>{:gfs:log_refund+111}
> > <ffffffffa024ad8e>{:gfs:log_flush_internal+510}
> > <ffffffff8017d682>{sync_supers+167}
> <ffffffff8015e310>{wb_kupdate+36}
> >
> > <ffffffff8015edb4>{pdflush+323} <ffffffff8015e2ec>{wb_kupdate+0}
> > <ffffffff8015ec71>{pdflush+0} <ffffffff8014aa93>{kthread+200}
> > <ffffffff80110e17>{child_rip+8}
> > <ffffffff8014aabc>{keventd_create_kthread+0}
> > <ffffffff8014a9cb>{kthread+0} <ffffffff80110e0f>{child_rip+0}
> > lock_dlm1 D 000001000c0096e0
> 0 5771 6 5772 5766
> > (L-TLB)
> > 0000010113ce3c58 0000000000000046 0000001000000000 0000010000000069
> > 000001011420b030 0000000000000069 000001000c00a940
> 000000010000eb10
> > 000001011a887030 0000000000001cae
> > Call Trace:<ffffffff802496d4>{__generic_unplug_device+19}
> > <ffffffff803053ef>{io_schedule+38}
> > <ffffffff80159215>{__lock_page+191}
> > <ffffffff80158cfa>{page_wake_function+0}
> > <ffffffff80158cfa>{page_wake_function+0}
> > <ffffffff80163125>{truncate_inode_pages+519}
> > <ffffffffa0258f35>{:gfs:gfs_inval_page+63}
> > <ffffffffa02401b5>{:gfs:drop_bh+233}
> > <ffffffffa0242138>{:gfs:gfs_glock_cb+194}
> > <ffffffffa02869dd>{:lock_dlm:dlm_async+1989}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffff8014aabc>{keventd_create_kthread+0}
> > <ffffffffa0286218>{:lock_dlm:dlm_async+0}
> > <ffffffff8014aabc>{keventd_create_kthread+0}
> > <ffffffff8014aa93>{kthread+200} <ffffffff80110e17>{child_rip+8}
> > <ffffffff8014aabc>{keventd_create_kthread+0}
> > <ffffffff8014a9cb>{kthread+0}
> > <ffffffff80110e0f>{child_rip+0}
> > gfs_logd D 0000000000000000
> 0 5776 1 5777 5775
> > (L-TLB)
> > 000001011387fe38 0000000000000046 0000000000000000 ffffffff80304a85
> > 000001011387fe58 ffffffff80304add ffffffff803cca80
> 0000000000000246
> > 00000101143fe030 00000000000000b5
> > Call Trace:<ffffffff80304a85>{thread_return+0}
> > <ffffffff80304add>{thread_return+88}
> > <ffffffffa023e8d3>{:gfs:lock_on_glock+112}
> > <ffffffff8030565b>{__down_write+134}
> > <ffffffffa0249cdb>{:gfs:gfs_ail_empty+56}
> > <ffffffffa0233930>{:gfs:gfs_logd+77}
> > <ffffffff80110e17>{child_rip+8}
> > <ffffffff801cccff>{dummy_d_instantiate+0}
> > <ffffffffa02338e3>{:gfs:gfs_logd+0}
> <ffffffff80110e0f>{child_rip+0}
> >
> > gfs_quotad D 0000000000000000
> 0 5777 1 5778 5776
> > (L-TLB)
> > 0000010113881e98 0000000000000046 0000000000000000 ffffffff80304a85
> > 0000010113881eb8 ffffffff80304add 000001011ff87030
> 0000000100000074
> > 000001011430f7f0 0000000000000128
> > Call Trace:<ffffffff80304a85>{thread_return+0}
> > <ffffffff80304add>{thread_return+88}
> > <ffffffff8030565b>{__down_write+134}
> > <ffffffffa025b55a>{:gfs:gfs_quota_sync+226}
> > <ffffffffa0233ab1>{:gfs:gfs_quotad+127}
> > <ffffffff80110e17>{child_rip+8}
> > <ffffffff801cccff>{dummy_d_instantiate+0}
> > <ffffffff801cccff>{dummy_d_instantiate+0}
> > <ffffffff801cccff>{dummy_d_instantiate+0}
> > <ffffffffa0233a32>{:gfs:gfs_quotad+0}
> > <ffffffff80110e0f>{child_rip+0}
> > gfs_inoded D 0000000000000000
> 0 5778 1 5807 5777
> > (L-TLB)
> > 0000010113883e98 0000000000000046 000001011e2937f0 000001000c0096e0
> > 0000000000000000 ffffffff80304a85 0000010113883ec8
> 0000000180304add
> > 000001011e2937f0 00000000000000c2
> > Call Trace:<ffffffff80304a85>{thread_return+0}
> > <ffffffff8030565b>{__down_write+134}
> > <ffffffffa026160d>{:gfs:unlinked_find+115}
> > <ffffffffa0261c6c>{:gfs:gfs_unlinked_dealloc+25}
> > <ffffffffa0233bd5>{:gfs:gfs_inoded+66}
> > <ffffffff80110e17>{child_rip+8}
> > <ffffffffa0233b93>{:gfs:gfs_inoded+0}
> <ffffffff80110e0f>{child_rip+0}
> >
> >
> > httpd D ffffffff80304190
> 0 5892 1 5893 5826
> > (NOTLB)
> > 0000010111b75bf8 0000000000000002 0000000000000001 0000000000000001
> > 0000000000000000 0000000000000000 0000010114667980
> 0000000111b75bc0
> > 00000101143fe7f0 00000000000009ad
> > Call Trace:<ffffffff80303d6f>{__down+147}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffff8015b3a2>{generic_file_write_nolock+158}
> > <ffffffff80305780>{__down_failed+53}
> > <ffffffffa0236986>{:gfs:.text.lock.dio+95}
> > <ffffffffa0260e4c>{:gfs:gfs_trans_add_bh+205}
> > <ffffffffa0253efc>{:gfs:do_write_buf+1138}
> > <ffffffffa0252db3>{:gfs:walk_vm+278}
> > <ffffffffa0253a8a>{:gfs:do_write_buf+0}
> > <ffffffffa0253a8a>{:gfs:do_write_buf+0}
> > <ffffffffa025415b>{:gfs:__gfs_write+201}
> > <ffffffff80177c60>{vfs_write+207}
> > <ffffffff80177d48>{sys_write+69}
> <ffffffff801101c6>{system_call+126}
> >
> > httpd D 0000010110ad7d48 0 5895
> 5892 5896 5893
> > (NOTLB)
> > 0000010110ad7bd8 0000000000000006 000001011b16e030 0000000000000075
> > 0000010117002030 0000000000000075 000001000c002940
> 0000000000000001
> > 00000101170027f0 000000000001300e
> > Call Trace:<ffffffff80131d1d>{try_to_wake_up+863}
> > <ffffffff80304cbd>{wait_for_completion+167}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffffa023f4b1>{:gfs:glock_wait_internal+350}
> > <ffffffffa023fce6>{:gfs:gfs_glock_nq+961}
> > <ffffffffa023ff11>{:gfs:gfs_glock_nq_init+20}
> > <ffffffffa0258b7b>{:gfs:gfs_private_nopage+84}
> > <ffffffff80168211>{do_no_page+1003}
> > <ffffffff80167b13>{do_wp_page+948}
> > <ffffffff8016858f>{handle_mm_fault+343}
> > <ffffffff80142a06>{get_signal_to_deliver+1118}
> > <ffffffff801236d2>{do_page_fault+518}
> > <ffffffff80304a85>{thread_return+0}
> > <ffffffff80304add>{thread_return+88}
> <ffffffff80110c61>{error_exit+0}
> >
> >
> > httpd D 0000010110b5bd48 0 5896
> 5892 5897 5895
> > (NOTLB)
> > 0000010110b5bbd8 0000000000000002 00000101170027f0 0000000000000075
> > 00000101114787f0 0000000000000075 000001000c002940
> 0000000000000001
> > 0000010117002030 000000000000fb3e
> > Call Trace:<ffffffff80131d1d>{try_to_wake_up+863}
> > <ffffffff80304cbd>{wait_for_completion+167}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffffa023f4b1>{:gfs:glock_wait_internal+350}
> > <ffffffffa023fce6>{:gfs:gfs_glock_nq+961}
> > <ffffffffa023ff11>{:gfs:gfs_glock_nq_init+20}
> > <ffffffffa0258b7b>{:gfs:gfs_private_nopage+84}
> > <ffffffff80168211>{do_no_page+1003}
> > <ffffffff80167b13>{do_wp_page+948}
> > <ffffffff8016858f>{handle_mm_fault+343}
> > <ffffffff80142a06>{get_signal_to_deliver+1118}
> > <ffffffff801236d2>{do_page_fault+518}
> > <ffffffff802a3445>{sys_accept+327}
> > <ffffffff80182e88>{pipe_read+26}
> <ffffffff80110c61>{error_exit+0}
> >
> > httpd D 0000000000000000 0 5897
> 5892 5911 5896
> > (NOTLB)
> > 0000010110119bd8 0000000000000006 0000010117002030 0000000000000075
> > 0000010117002030 0000000000000075 000001000c00a940
> 000000001b16e030
> > 00000101114787f0 000000000000fbe0
> > Call Trace:<ffffffff802496d4>{__generic_unplug_device+19}
> > <ffffffff80304cbd>{wait_for_completion+167}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffffa023f4b1>{:gfs:glock_wait_internal+350}
> > <ffffffffa023fce6>{:gfs:gfs_glock_nq+961}
> > <ffffffffa023ff11>{:gfs:gfs_glock_nq_init+20}
> > <ffffffffa0258b7b>{:gfs:gfs_private_nopage+84}
> > <ffffffff80168211>{do_no_page+1003}
> > <ffffffff80167b13>{do_wp_page+948}
> > <ffffffff8016858f>{handle_mm_fault+343}
> > <ffffffff80142a06>{get_signal_to_deliver+1118}
> > <ffffffff801236d2>{do_page_fault+518}
> > <ffffffff80304a85>{thread_return+0}
> > <ffffffff80304add>{thread_return+88}
> <ffffffff80110c61>{error_exit+0}
> >
> >
> > httpd D 00000101100c3d48 0 5911
> 5892 5915 5897
> > (NOTLB)
> > 00000101100c3bd8 0000000000000002 000001011420b7f0 0000000000000075
> > 00000101170027f0 0000000000000075 000001000c002940
> 0000000000000000
> > 000001011b16e030 000000000000187e
> > Call Trace:<ffffffff80131d1d>{try_to_wake_up+863}
> > <ffffffff80304cbd>{wait_for_completion+167}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffff801333c8>{default_wake_function+0}
> > <ffffffffa023f4b1>{:gfs:glock_wait_internal+350}
> > <ffffffffa023fce6>{:gfs:gfs_glock_nq+961}
> > <ffffffffa023ff11>{:gfs:gfs_glock_nq_init+20}
> > <ffffffffa0258b7b>{:gfs:gfs_private_nopage+84}
> > <ffffffff80168211>{do_no_page+1003}
> > <ffffffff80167b13>{do_wp_page+948}
> > <ffffffff8016858f>{handle_mm_fault+343}
> > <ffffffff80142a06>{get_signal_to_deliver+1118}
> > <ffffffff801236d2>{do_page_fault+518}
> > <ffffffff80304a85>{thread_return+0}
> > <ffffffff80304add>{thread_return+88}
> <ffffffff80110c61>{error_exit+0}
> >
> >
> > httpd D 0000000000006a36 0 5915
> 5892 5911
> > (NOTLB)
> > 00000101180f7ad8 0000000000000006 0000000000002706 ffffffffa020c791
> > 0000000000000000 0000000000000000 0000030348ac8c1c
> 0000000114a217f0
> > 0000010114c997f0 000000000000076a
> > Call Trace:<ffffffffa020c791>{:dlm:lkb_swqueue+43}
> > <ffffffff803053ef>{io_schedule+38}
> > <ffffffff80178c4c>{__wait_on_buffer+125}
> > <ffffffff80178ad2>{bh_wake_function+0}
> > <ffffffff80178ad2>{bh_wake_function+0}
> > <ffffffffa02352c6>{:gfs:gfs_dreread+154}
> > <ffffffffa0235332>{:gfs:gfs_dread+40}
> > <ffffffffa02363b1>{:gfs:gfs_get_meta_buffer+201}
> > <ffffffffa0242999>{:gfs:gfs_copyin_dinode+23}
> > <ffffffffa0242461>{:gfs:inode_go_lock+38}
> > <ffffffffa023f586>{:gfs:glock_wait_internal+563}
> > <ffffffffa023fce6>{:gfs:gfs_glock_nq+961}
> > <ffffffffa023ff11>{:gfs:gfs_glock_nq_init+20}
> > <ffffffffa0258b7b>{:gfs:gfs_private_nopage+84}
> > <ffffffff80168211>{do_no_page+1003}
> > <ffffffff80167b13>{do_wp_page+948}
> > <ffffffff8016858f>{handle_mm_fault+343}
> > <ffffffff80142a06>{get_signal_to_deliver+1118}
> > <ffffffff801236d2>{do_page_fault+518}
> > <ffffffff80304a85>{thread_return+0}
> > <ffffffff80304add>{thread_return+88}
> <ffffffff80110c61>{error_exit+0}
> >
> >
> > sh D 000000000000001a 0 5930 2547
> > (NOTLB)
> > 000001011090f8e8 0000000000000002 0000010111293d88 0000010110973d00
> > 0000010111293d88 0000000000000000 00000100dfc02400
> 0000000000010000
> > 00000101148557f0 0000000000002010
> > Call Trace:<ffffffff803053ef>{io_schedule+38}
> > <ffffffff80178c4c>{__wait_on_buffer+125}
> > <ffffffff80178ad2>{bh_wake_function+0}
> > <ffffffff80178ad2>{bh_wake_function+0}
> > <ffffffffa02352c6>{:gfs:gfs_dreread+154}
> > <ffffffffa0235332>{:gfs:gfs_dread+40}
> > <ffffffffa02363b1>{:gfs:gfs_get_meta_buffer+201}
> > <ffffffffa0242999>{:gfs:gfs_copyin_dinode+23}
> > <ffffffffa0242461>{:gfs:inode_go_lock+38}
> > <ffffffffa023f586>{:gfs:glock_wait_internal+563}
> > <ffffffffa023fce6>{:gfs:gfs_glock_nq+961}
> > <ffffffffa023ff11>{:gfs:gfs_glock_nq_init+20}
> > <ffffffff801ccb78>{dummy_inode_permission+0}
> > <ffffffffa0257aca>{:gfs:gfs_permission+64}
> > <ffffffff8018d475>{dput+56} <ffffffff80183d32>{permission+51}
> > <ffffffff801844aa>{__link_path_walk+372}
> > <ffffffff801851c2>{link_path_walk+82}
> > <ffffffff8012370b>{do_page_fault+575}
> > <ffffffff801849b0>{__link_path_walk+1658}
> > <ffffffff801851c2>{link_path_walk+82}
> > <ffffffff8012370b>{do_page_fault+575}
> > <ffffffff8018540f>{path_lookup+451}
> > <ffffffff801856bb>{__user_walk+47}
> > <ffffffff8017ff1a>{vfs_stat+24}
> <ffffffff8012370b>{do_page_fault+575}
> >
> > <ffffffff80180264>{sys_newstat+17}
> <ffffffff80110c61>{error_exit+0}
> > <ffffffff801101c6>{system_call+126}
>
> --
> Best Regards,
> Anton Kornev.
>
> References
>
> Visible links
> 1. mailto:teigland@xxxxxxxxxx
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