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  1. 30 8月, 2015 1 次提交
  3. 20 8月, 2015 1 次提交
  5. 18 8月, 2015 1 次提交
    • T
      SUNRPC: Fix a thinko in xs_connect() · 99b1a4c3
      由 Trond Myklebust 提交于 
      It is rather pointless to test the value of transport->inet after
calling xs_reset_transport(), since it will always be zero, and
so we will never see any exponential back off behaviour.
Also don't force early connections for SOFTCONN tasks. If the server
disconnects us, we should respect the exponential backoff.

Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      99b1a4c3
  7. 28 7月, 2015 1 次提交
  9. 27 7月, 2015 1 次提交
    • N
      sunrpc: translate -EAGAIN to -ENOBUFS when socket is writable. · 743c69e7
      由 NeilBrown 提交于 
      The networking layer does not reliably report the distinction between
a non-block write failing because:
 1/ the queue is too full already and
 2/ a memory allocation attempt failed.

The distinction is important because in the first case it is
appropriate to retry as soon as the socket reports that it is
writable, and in the second case a small delay is required as the
socket will most likely report as writable but kmalloc could still
fail.

sk_stream_wait_memory() exhibits this distinction nicely, setting
'vm_wait' if a small wait is needed.  However in the non-blocking case
it always returns -EAGAIN no matter the cause of the failure.  This
-EAGAIN call get all the way to sunrpc.

The sunrpc layer expects EAGAIN to indicate the first cause, and
ENOBUFS to indicate the second.  Various documentation suggests that
this is not unreasonable, but does not guarantee the desired error
codes.

The result of getting -EAGAIN when -ENOBUFS is expected is that the
send is tried again in a tight loop and soft lockups are reported.

so: add tests after calls to xs_sendpages() to translate -EAGAIN into
-ENOBUFS if the socket is writable.  This cannot happen inside
xs_sendpages() as the test for "is socket writable" is different
between TCP and UDP.

With this change, the tight loop retrying xs_sendpages() becomes a
loop which only retries every 250ms, and so will not trigger a
soft-lockup warning.

It is possible that the write did fail because the queue was too full
and by the time xs_sendpages() completed, the queue was writable
again.  In this case an extra 250ms delay is inserted that isn't
really needed.  This circumstance suggests a degree of congestion so a
delay is not necessarily a bad thing, and it can only cause a single
250ms delay, not a series of them.
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      743c69e7
  11. 03 7月, 2015 1 次提交
  13. 21 6月, 2015 1 次提交
  15. 20 6月, 2015 1 次提交
  17. 11 6月, 2015 6 次提交
  19. 02 6月, 2015 1 次提交
  21. 28 5月, 2015 1 次提交
    • L
      kernel/params: constify struct kernel_param_ops uses · 9c27847d
      由 Luis R. Rodriguez 提交于 
      Most code already uses consts for the struct kernel_param_ops,
sweep the kernel for the last offending stragglers. Other than
include/linux/moduleparam.h and kernel/params.c all other changes
were generated with the following Coccinelle SmPL patch. Merge
conflicts between trees can be handled with Coccinelle.

In the future git could get Coccinelle merge support to deal with
patch --> fail --> grammar --> Coccinelle --> new patch conflicts
automatically for us on patches where the grammar is available and
the patch is of high confidence. Consider this a feature request.

Test compiled on x86_64 against:

	* allnoconfig
	* allmodconfig
	* allyesconfig

@ const_found @
identifier ops;
@@

const struct kernel_param_ops ops = {
};

@ const_not_found depends on !const_found @
identifier ops;
@@

-struct kernel_param_ops ops = {
+const struct kernel_param_ops ops = {
};

Generated-by: Coccinelle SmPL
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Junio C Hamano <gitster@pobox.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: cocci@systeme.lip6.fr
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NLuis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
      9c27847d
  23. 11 2月, 2015 1 次提交
  25. 10 2月, 2015 5 次提交
  27. 09 2月, 2015 10 次提交
  29. 25 11月, 2014 3 次提交
  31. 25 9月, 2014 4 次提交
    • N
      NFS/SUNRPC: Remove other deadlock-avoidance mechanisms in nfs_release_page() · 1aff5256
      由 NeilBrown 提交于 
      Now that nfs_release_page() doesn't block indefinitely, other deadlock
avoidance mechanisms aren't needed.
 - it doesn't hurt for kswapd to block occasionally.  If it doesn't
   want to block it would clear __GFP_WAIT.  The current_is_kswapd()
   was only added to avoid deadlocks and we have a new approach for
   that.
 - memory allocation in the SUNRPC layer can very rarely try to
   ->releasepage() a page it is trying to handle.  The deadlock
   is removed as nfs_release_page() doesn't block indefinitely.

So we don't need to set PF_FSTRANS for sunrpc network operations any
more.
Signed-off-by: NNeilBrown <neilb@suse.de>
Acked-by: NJeff Layton <jlayton@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      1aff5256
    • J
      rpc: Add -EPERM processing for xs_udp_send_request() · 3dedbb5c
      由 Jason Baron 提交于 
      If an iptables drop rule is added for an nfs server, the client can end up in
a softlockup. Because of the way that xs_sendpages() is structured, the -EPERM
is ignored since the prior bits of the packet may have been successfully queued
and thus xs_sendpages() returns a non-zero value. Then, xs_udp_send_request()
thinks that because some bits were queued it should return -EAGAIN. We then try
the request again and again, resulting in cpu spinning. Reproducer:

1) open a file on the nfs server '/nfs/foo' (mounted using udp)
2) iptables -A OUTPUT -d <nfs server ip> -j DROP
3) write to /nfs/foo
4) close /nfs/foo
5) iptables -D OUTPUT -d <nfs server ip> -j DROP

The softlockup occurs in step 4 above.

The previous patch, allows xs_sendpages() to return both a sent count and
any error values that may have occurred. Thus, if we get an -EPERM, return
that to the higher level code.

With this patch in place we can successfully abort the above sequence and
avoid the softlockup.

I also tried the above test case on an nfs mount on tcp and although the system
does not softlockup, I still ended up with the 'hung_task' firing after 120
seconds, due to the i/o being stuck. The tcp case appears a bit harder to fix,
since -EPERM appears to get ignored much lower down in the stack and does not
propogate up to xs_sendpages(). This case is not quite as insidious as the
softlockup and it is not addressed here.
Reported-by: NYigong Lou <ylou@akamai.com>
Signed-off-by: NJason Baron <jbaron@akamai.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      3dedbb5c
    • J
      rpc: return sent and err from xs_sendpages() · f279cd00
      由 Jason Baron 提交于 
      If an error is returned after the first bits of a packet have already been
successfully queued, xs_sendpages() will return a positive 'int' value
indicating success. Callers seem to treat this as -EAGAIN.

However, there are cases where its not a question of waiting for the write
queue to drain. For example, when there is an iptables rule dropping packets
to the destination, the lower level code can return -EPERM only after parts
of the packet have been successfully queued. In this case, we can end up
continuously retrying resulting in a kernel softlockup.

This patch is intended to make no changes in behavior but is in preparation for
subsequent patches that can make decisions based on both on the number of bytes
sent by xs_sendpages() and any errors that may have be returned.
Signed-off-by: NJason Baron <jbaron@akamai.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      f279cd00
    • B
      SUNRPC: Don't wake tasks during connection abort · a743419f
      由 Benjamin Coddington 提交于 
      When aborting a connection to preserve source ports, don't wake the task in
xs_error_report.  This allows tasks with RPC_TASK_SOFTCONN to succeed if the
connection needs to be re-established since it preserves the task's status
instead of setting it to the status of the aborting kernel_connect().

This may also avoid a potential conflict on the socket's lock.
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
Cc: stable@vger.kernel.org # 3.14+
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      a743419f
  33. 11 9月, 2014 1 次提交
    • C
      rpc: xs_bind - do not bind when requesting a random ephemeral port · 0f7a622c
      由 Chris Perl 提交于 
      When attempting to establish a local ephemeral endpoint for a TCP or UDP
socket, do not explicitly call bind, instead let it happen implicilty when the
socket is first used.

The main motivating factor for this change is when TCP runs out of unique
ephemeral ports (i.e.  cannot find any ephemeral ports which are not a part of
*any* TCP connection).  In this situation if you explicitly call bind, then the
call will fail with EADDRINUSE.  However, if you allow the allocation of an
ephemeral port to happen implicitly as part of connect (or other functions),
then ephemeral ports can be reused, so long as the combination of (local_ip,
local_port, remote_ip, remote_port) is unique for TCP sockets on the system.

This doesn't matter for UDP sockets, but it seemed easiest to treat TCP and UDP
sockets the same.

This can allow mount.nfs(8) to continue to function successfully, even in the
face of misbehaving applications which are creating a large number of TCP
connections.
Signed-off-by: NChris Perl <chris.perl@gmail.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>
      0f7a622c