SUNRPC: avoid race between mod_timer() and del_timer_sync()

commit 3848e96edf4788f772d83990022fa7023a233d83 upstream.

xprt_destory() claims XPRT_LOCKED and then calls del_timer_sync().
Both xprt_un

SUNRPC: avoid race between mod_timer() and del_timer_sync()

commit 3848e96edf4788f772d83990022fa7023a233d83 upstream.

xprt_destory() claims XPRT_LOCKED and then calls del_timer_sync().
Both xprt_unlock_connect() and xprt_release() call
->release_xprt()
which drops XPRT_LOCKED and *then* xprt_schedule_autodisconnect()
which calls mod_timer().

This may result in mod_timer() being called *after* del_timer_sync().
When this happens, the timer may fire long after the xprt has been freed,
and run_timer_softirq() will probably crash.

The pairing of ->release_xprt() and xprt_schedule_autodisconnect() is
always called under ->transport_lock. So if we take ->transport_lock to
call del_timer_sync(), we can be sure that mod_timer() will run first
(if it runs at all).

Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

SUNRPC: Partial revert of commit 6f9f17287e78

commit ea7a1019d8baf8503ecd6e3ec8436dec283569e6 upstream.

The premise of commit 6f9f17287e78 ("SUNRPC: Mitigate cond_resched() in
xprt_transmit()") was

SUNRPC: Partial revert of commit 6f9f17287e78

commit ea7a1019d8baf8503ecd6e3ec8436dec283569e6 upstream.

The premise of commit 6f9f17287e78 ("SUNRPC: Mitigate cond_resched() in
xprt_transmit()") was that cond_resched() is expensive and unnecessary
when there has been just a single send.
The point of cond_resched() is to ensure that tasks that should pre-empt
this one get a chance to do so when it is safe to do so. The code prior
to commit 6f9f17287e78 failed to take into account that it was keeping a
rpc_task pinned for longer than it needed to, and so rather than doing a
full revert, let's just move the cond_resched.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

SUNRPC: Move client-side disconnect injection

Disconnect injection stress-tests the ability for both client and
server implementations to behave resiliently in the face of network
instability.

Conv

SUNRPC: Move client-side disconnect injection

Disconnect injection stress-tests the ability for both client and
server implementations to behave resiliently in the face of network
instability.

Convert the existing client-side disconnect injection infrastructure
to use the kernel's generic error injection facility. The generic
facility has a richer set of injection criteria.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

show more ...

SUNRPC/xprtrdma: Fix reconnection locking

The xprtrdma client code currently relies on the task that initiated the
connect to hold the XPRT_LOCK for the duration of the connection
attempt. If the ta

SUNRPC/xprtrdma: Fix reconnection locking

The xprtrdma client code currently relies on the task that initiated the
connect to hold the XPRT_LOCK for the duration of the connection
attempt. If the task is woken early, due to some other event, then that
lock could get released early.
Avoid races by using the same mechanism that the socket code uses of
transferring lock ownership to the RDMA connect worker itself. That
frees us to call rpcrdma_xprt_disconnect() directly since we're now
guaranteed exclusion w.r.t. other callers.

Fixes: 4cf44be6f1e8 ("xprtrdma: Fix recursion into rpcrdma_xprt_disconnect()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

show more ...

SUNRPC: Clean up scheduling of autoclose

Consolidate duplicated code in xprt_force_disconnect() and
xprt_conditional_disconnect().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
S

SUNRPC: Clean up scheduling of autoclose

Consolidate duplicated code in xprt_force_disconnect() and
xprt_conditional_disconnect().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

show more ...

SUNRPC: Fix potential memory corruption

We really should not call rpc_wake_up_queued_task_set_status() with
xprt->snd_task as an argument unless we are certain that is actually an
rpc_task.

Fixes:

SUNRPC: Fix potential memory corruption

We really should not call rpc_wake_up_queued_task_set_status() with
xprt->snd_task as an argument unless we are certain that is actually an
rpc_task.

Fixes: 0445f92c5d53 ("SUNRPC: Fix disconnection races")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

show more ...

sunrpc: add dst_attr attributes to the sysfs xprt directory

Allow to query and set the destination's address of a transport.
Setting of the destination address is allowed only for TCP or RDMA
based

sunrpc: add dst_attr attributes to the sysfs xprt directory

Allow to query and set the destination's address of a transport.
Setting of the destination address is allowed only for TCP or RDMA
based connections.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

sunrpc: add xprt id

This adds a unique identifier for a sunrpc transport in sysfs, which is
similarly managed to the unique IDs of clients.

Signed-off-by: Dan Aloni <dan@kernelim.com>
Signed-off-by

sunrpc: add xprt id

This adds a unique identifier for a sunrpc transport in sysfs, which is
similarly managed to the unique IDs of clients.

Signed-off-by: Dan Aloni <dan@kernelim.com>
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: More fixes for backlog congestion

Ensure that we fix the XPRT_CONGESTED starvation issue for RDMA as well
as socket based transports.
Ensure we always initialise the request after waking up

SUNRPC: More fixes for backlog congestion

Ensure that we fix the XPRT_CONGESTED starvation issue for RDMA as well
as socket based transports.
Ensure we always initialise the request after waking up from the backlog
list.

Fixes: e877a88d1f06 ("SUNRPC in case of backlog, hand free slots directly to waiting task")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC in case of backlog, hand free slots directly to waiting task

If sunrpc.tcp_max_slot_table_entries is small and there are tasks
on the backlog queue, then when a request completes it is freed

SUNRPC in case of backlog, hand free slots directly to waiting task

If sunrpc.tcp_max_slot_table_entries is small and there are tasks
on the backlog queue, then when a request completes it is freed and the
first task on the queue is woken. The expectation is that it will wake
and claim that request. However if it was a sync task and the waiting
process was killed at just that moment, it will wake and NOT claim the
request.

As long as TASK_CONGESTED remains set, requests can only be claimed by
tasks woken from the backlog, and they are woken only as requests are
freed, so when a task doesn't claim a request, no other task can ever
get that request until TASK_CONGESTED is cleared. Each time this
happens the number of available requests is decreased by one.

With a sufficiently high workload and sufficiently low setting of
max_slot (16 in the case where this was seen), TASK_CONGESTED can remain
set for an extended period, and the above scenario (of a process being
killed just as its task was woken) can repeat until no requests can be
allocated. Then traffic stops.

This patch addresses the problem by introducing a positive handover of a
request from a completing task to a backlog task - the request is never
freed when there is a backlog.

When a task is woken it might not already have a request attached in
which case it is *not* freed (as with current code) but is initialised
(if needed) and used. If it isn't used it will eventually be freed by
rpc_exit_task(). xprt_release() is enhanced to be able to correctly
release an uninitialised request.

Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue")
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: Handle major timeout in xprt_adjust_timeout()

Currently if a major timeout value is reached, but the minor value has
not been reached, an ETIMEOUT will not be sent back to the caller.
This c

SUNRPC: Handle major timeout in xprt_adjust_timeout()

Currently if a major timeout value is reached, but the minor value has
not been reached, an ETIMEOUT will not be sent back to the caller.
This can occur if the v4 server is not responding to requests and
retrans is configured larger than the default of two.

For example, A TCP mount with a configured timeout value of 50 and a
retransmission count of 3 to a v4 server which is not responding:

1. Initial value and increment set to 5s, maxval set to 20s, retries at 3
2. Major timeout is set to 20s, minor timeout set to 5s initially
3. xport_adjust_timeout() is called after 5s, retry with 10s timeout,
minor timeout is bumped to 10s
4. And again after another 10s, 15s total time with minor timeout set
to 15s
5. After 20s total time xport_adjust_timeout is called as major timeout is
reached, but skipped because the minor timeout is not reached
- After this time the cpu spins continually calling
xport_adjust_timeout() and returning 0 for 10 seconds.
As seen on perf sched:
39243.913182 [0005] mount.nfs[3794] 4607.938 0.017 9746.863
6. This continues until the 15s minor timeout condition is reached (in
this case for 10 seconds). After which the ETIMEOUT is processed
back to the caller, the cpu spinning stops, and normal operations
continue

Fixes: 7de62bc09fe6 ("SUNRPC dont update timeout value on connection reset")
Signed-off-by: Chris Dion <Christopher.Dion@dell.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: Remove trace_xprt_transmit_queued

This tracepoint can crash when dereferencing snd_task because
when some transports connect, they put a cookie in that field
instead of a pointer to an rpc_t

SUNRPC: Remove trace_xprt_transmit_queued

This tracepoint can crash when dereferencing snd_task because
when some transports connect, they put a cookie in that field
instead of a pointer to an rpc_task.

BUG: KASAN: use-after-free in trace_event_raw_event_xprt_writelock_event+0x141/0x18e [sunrpc]
Read of size 2 at addr ffff8881a83bd3a0 by task git/331872

CPU: 11 PID: 331872 Comm: git Tainted: G S 5.12.0-rc2-00007-g3ab6e585a7f9 #1453
Hardware name: Supermicro SYS-6028R-T/X10DRi, BIOS 1.1a 10/16/2015
Call Trace:
dump_stack+0x9c/0xcf
print_address_description.constprop.0+0x18/0x239
kasan_report+0x174/0x1b0
trace_event_raw_event_xprt_writelock_event+0x141/0x18e [sunrpc]
xprt_prepare_transmit+0x8e/0xc1 [sunrpc]
call_transmit+0x4d/0xc6 [sunrpc]

Fixes: 9ce07ae5eb1d ("SUNRPC: Replace dprintk() call site in xprt_prepare_transmit")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: Add tracepoint that fires when an RPC is retransmitted

A separate tracepoint can be left enabled all the time to capture
rare but important retransmission events. So for example:

kworker/u2

SUNRPC: Add tracepoint that fires when an RPC is retransmitted

A separate tracepoint can be left enabled all the time to capture
rare but important retransmission events. So for example:

kworker/u26:3-568 [009] 156.967933: xprt_retransmit: task:44093@5 xid=0xa25dbc79 nfsv3 WRITE ntrans=2

Or, for example, enable all nfs and nfs4 tracepoints, and set up a
trigger to disable tracing when xprt_retransmit fires to capture
everything that leads up to it.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: Move fault injection call sites

I've hit some crashes that occur in the xprt_rdma_inject_disconnect
path. It appears that, for some provides, rdma_disconnect() can
take so long that the tran

SUNRPC: Move fault injection call sites

I've hit some crashes that occur in the xprt_rdma_inject_disconnect
path. It appears that, for some provides, rdma_disconnect() can
take so long that the transport can disconnect and release its
hardware resources while rdma_disconnect() is still running,
resulting in a UAF in the provider.

The transport's fault injection method may depend on the stability
of transport data structures. That means it needs to be invoked
only from contexts that hold the transport write lock.

Fixes: 4a0682583988 ("SUNRPC: Transport fault injection")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: Set TCP_CORK until the transmit queue is empty

When we have multiple RPC requests queued up, it makes sense to set the
TCP_CORK option while the transmit queue is non-empty.

Signed-off-by:

SUNRPC: Set TCP_CORK until the transmit queue is empty

When we have multiple RPC requests queued up, it makes sense to set the
TCP_CORK option while the transmit queue is non-empty.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: Remove unused function xprt_load_transport()

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

SUNRPC: Add a helper to return the transport identifier given a netid

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

SUNRPC: Close a race with transport setup and module put

After we've looked up the transport module, we need to ensure it can't
go away until we've finished running the transport setup code.

Signed

SUNRPC: Close a race with transport setup and module put

After we've looked up the transport module, we need to ensure it can't
go away until we've finished running the transport setup code.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC: xprt_load_transport() needs to support the netid "rdma6"

According to RFC5666, the correct netid for an IPv6 addressed RDMA
transport is "rdma6", which we've supported as a mount option sinc

SUNRPC: xprt_load_transport() needs to support the netid "rdma6"

According to RFC5666, the correct netid for an IPv6 addressed RDMA
transport is "rdma6", which we've supported as a mount option since
Linux-4.7. The problem is when we try to load the module "xprtrdma6",
that will fail, since there is no modulealias of that name.

Fixes: 181342c5ebe8 ("xprtrdma: Add rdma6 option to support NFS/RDMA IPv6")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

show more ...

SUNRPC/xprtrdma: Fix reconnection locking

[ Upstream commit f99fa50880f5300fbbb3c0754ddc7f8738d24fe7 ]

The xprtrdma client code currently relies on the task that initiated the
connect to hold the X

SUNRPC/xprtrdma: Fix reconnection locking

[ Upstream commit f99fa50880f5300fbbb3c0754ddc7f8738d24fe7 ]

The xprtrdma client code currently relies on the task that initiated the
connect to hold the XPRT_LOCK for the duration of the connection
attempt. If the task is woken early, due to some other event, then that
lock could get released early.
Avoid races by using the same mechanism that the socket code uses of
transferring lock ownership to the RDMA connect worker itself. That
frees us to call rpcrdma_xprt_disconnect() directly since we're now
guaranteed exclusion w.r.t. other callers.

Fixes: 4cf44be6f1e8 ("xprtrdma: Fix recursion into rpcrdma_xprt_disconnect()")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

SUNRPC: Fix potential memory corruption

[ Upstream commit c2dc3e5fad13aca5d7bdf4bcb52b1a1d707c8555 ]

We really should not call rpc_wake_up_queued_task_set_status() with
xprt->snd_task as an argumen

SUNRPC: Fix potential memory corruption

[ Upstream commit c2dc3e5fad13aca5d7bdf4bcb52b1a1d707c8555 ]

We really should not call rpc_wake_up_queued_task_set_status() with
xprt->snd_task as an argument unless we are certain that is actually an
rpc_task.

Fixes: 0445f92c5d53 ("SUNRPC: Fix disconnection races")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

SUNRPC: More fixes for backlog congestion

commit e86be3a04bc4aeaf12f93af35f08f8d4385bcd98 upstream.

Ensure that we fix the XPRT_CONGESTED starvation issue for RDMA as well
as socket based transport

SUNRPC: More fixes for backlog congestion

commit e86be3a04bc4aeaf12f93af35f08f8d4385bcd98 upstream.

Ensure that we fix the XPRT_CONGESTED starvation issue for RDMA as well
as socket based transports.
Ensure we always initialise the request after waking up from the backlog
list.

Fixes: e877a88d1f06 ("SUNRPC in case of backlog, hand free slots directly to waiting task")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

SUNRPC in case of backlog, hand free slots directly to waiting task

commit e877a88d1f069edced4160792f42c2a8e2dba942 upstream.

If sunrpc.tcp_max_slot_table_entries is small and there are tasks
on th

SUNRPC in case of backlog, hand free slots directly to waiting task

commit e877a88d1f069edced4160792f42c2a8e2dba942 upstream.

If sunrpc.tcp_max_slot_table_entries is small and there are tasks
on the backlog queue, then when a request completes it is freed and the
first task on the queue is woken. The expectation is that it will wake
and claim that request. However if it was a sync task and the waiting
process was killed at just that moment, it will wake and NOT claim the
request.

As long as TASK_CONGESTED remains set, requests can only be claimed by
tasks woken from the backlog, and they are woken only as requests are
freed, so when a task doesn't claim a request, no other task can ever
get that request until TASK_CONGESTED is cleared. Each time this
happens the number of available requests is decreased by one.

With a sufficiently high workload and sufficiently low setting of
max_slot (16 in the case where this was seen), TASK_CONGESTED can remain
set for an extended period, and the above scenario (of a process being
killed just as its task was woken) can repeat until no requests can be
allocated. Then traffic stops.

This patch addresses the problem by introducing a positive handover of a
request from a completing task to a backlog task - the request is never
freed when there is a backlog.

When a task is woken it might not already have a request attached in
which case it is *not* freed (as with current code) but is initialised
(if needed) and used. If it isn't used it will eventually be freed by
rpc_exit_task(). xprt_release() is enhanced to be able to correctly
release an uninitialised request.

Fixes: ba60eb25ff6b ("SUNRPC: Fix a livelock problem in the xprt->backlog queue")
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

SUNRPC: Handle major timeout in xprt_adjust_timeout()

[ Upstream commit 09252177d5f924f404551b4b4eded5daa7f04a3a ]

Currently if a major timeout value is reached, but the minor value has
not been re

SUNRPC: Handle major timeout in xprt_adjust_timeout()

[ Upstream commit 09252177d5f924f404551b4b4eded5daa7f04a3a ]

Currently if a major timeout value is reached, but the minor value has
not been reached, an ETIMEOUT will not be sent back to the caller.
This can occur if the v4 server is not responding to requests and
retrans is configured larger than the default of two.

For example, A TCP mount with a configured timeout value of 50 and a
retransmission count of 3 to a v4 server which is not responding:

1. Initial value and increment set to 5s, maxval set to 20s, retries at 3
2. Major timeout is set to 20s, minor timeout set to 5s initially
3. xport_adjust_timeout() is called after 5s, retry with 10s timeout,
minor timeout is bumped to 10s
4. And again after another 10s, 15s total time with minor timeout set
to 15s
5. After 20s total time xport_adjust_timeout is called as major timeout is
reached, but skipped because the minor timeout is not reached
- After this time the cpu spins continually calling
xport_adjust_timeout() and returning 0 for 10 seconds.
As seen on perf sched:
39243.913182 [0005] mount.nfs[3794] 4607.938 0.017 9746.863
6. This continues until the 15s minor timeout condition is reached (in
this case for 10 seconds). After which the ETIMEOUT is processed
back to the caller, the cpu spinning stops, and normal operations
continue

Fixes: 7de62bc09fe6 ("SUNRPC dont update timeout value on connection reset")
Signed-off-by: Chris Dion <Christopher.Dion@dell.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

SUNRPC: Remove trace_xprt_transmit_queued

[ Upstream commit 6cf23783f750634e10daeede48b0f5f5d64ebf3a ]

This tracepoint can crash when dereferencing snd_task because
when some transports connect, th

SUNRPC: Remove trace_xprt_transmit_queued

[ Upstream commit 6cf23783f750634e10daeede48b0f5f5d64ebf3a ]

This tracepoint can crash when dereferencing snd_task because
when some transports connect, they put a cookie in that field
instead of a pointer to an rpc_task.

BUG: KASAN: use-after-free in trace_event_raw_event_xprt_writelock_event+0x141/0x18e [sunrpc]
Read of size 2 at addr ffff8881a83bd3a0 by task git/331872

CPU: 11 PID: 331872 Comm: git Tainted: G S 5.12.0-rc2-00007-g3ab6e585a7f9 #1453
Hardware name: Supermicro SYS-6028R-T/X10DRi, BIOS 1.1a 10/16/2015
Call Trace:
dump_stack+0x9c/0xcf
print_address_description.constprop.0+0x18/0x239
kasan_report+0x174/0x1b0
trace_event_raw_event_xprt_writelock_event+0x141/0x18e [sunrpc]
xprt_prepare_transmit+0x8e/0xc1 [sunrpc]
call_transmit+0x4d/0xc6 [sunrpc]

Fixes: 9ce07ae5eb1d ("SUNRPC: Replace dprintk() call site in xprt_prepare_transmit")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...