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  1. 06 Feb, 2018 3 commits
    • Ross Lagerwall's avatar
      xen-netfront: Fix race between device setup and open · f599c64f
      Ross Lagerwall authored 
      When a netfront device is set up it registers a netdev fairly early on,
before it has set up the queues and is actually usable. A userspace tool
like NetworkManager will immediately try to open it and access its state
as soon as it appears. The bug can be reproduced by hotplugging VIFs
until the VM runs out of grant refs. It registers the netdev but fails
to set up any queues (since there are no more grant refs). In the
meantime, NetworkManager opens the device and the kernel crashes trying
to access the queues (of which there are none).

Fix this in two ways:
* For initial setup, register the netdev much later, after the queues
are setup. This avoids the race entirely.
* During a suspend/resume cycle, the frontend reconnects to the backend
and the queues are recreated. It is possible (though highly unlikely) to
race with something opening the device and accessing the queues after
they have been destroyed but before they have been recreated. Extend the
region covered by the rtnl semaphore to protect against this race. There
is a possibility that we fail to recreate the queues so check for this
in the open function.
Signed-off-by: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
      f599c64f
    • Ross Lagerwall's avatar
      xen/grant-table: Use put_page instead of free_page · 3ac7292a
      Ross Lagerwall authored 
      The page given to gnttab_end_foreign_access() to free could be a
compound page so use put_page() instead of free_page() since it can
handle both compound and single pages correctly.

This bug was discovered when migrating a Xen VM with several VIFs and
CONFIG_DEBUG_VM enabled. It hits a BUG usually after fewer than 10
iterations. All netfront devices disconnect from the backend during a
suspend/resume and this will call gnttab_end_foreign_access() if a
netfront queue has an outstanding skb. The mismatch between calling
get_page() and free_page() on a compound page causes a reference
counting error which is detected when DEBUG_VM is enabled.
Signed-off-by: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
      3ac7292a
    • Juergen Gross's avatar
      x86/xen: init %gs very early to avoid page faults with stack protector · 4f277295
      Juergen Gross authored 
      When running as Xen pv guest %gs is initialized some time after
C code is started. Depending on stack protector usage this might be
too late, resulting in page faults.

So setup %gs and MSR_GS_BASE in assembly code already.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: default avatarChris Patterson <cjp256@gmail.com>
Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
      4f277295
  3. 29 Jan, 2018 1 commit
  5. 28 Jan, 2018 8 commits
  7. 27 Jan, 2018 2 commits
    • Thomas Gleixner's avatar
      hrtimer: Reset hrtimer cpu base proper on CPU hotplug · d5421ea4
      Thomas Gleixner authored 
      The hrtimer interrupt code contains a hang detection and mitigation
mechanism, which prevents that a long delayed hrtimer interrupt causes a
continous retriggering of interrupts which prevent the system from making
progress. If a hang is detected then the timer hardware is programmed with
a certain delay into the future and a flag is set in the hrtimer cpu base
which prevents newly enqueued timers from reprogramming the timer hardware
prior to the chosen delay. The subsequent hrtimer interrupt after the delay
clears the flag and resumes normal operation.

If such a hang happens in the last hrtimer interrupt before a CPU is
unplugged then the hang_detected flag is set and stays that way when the
CPU is plugged in again. At that point the timer hardware is not armed and
it cannot be armed because the hang_detected flag is still active, so
nothing clears that flag. As a consequence the CPU does not receive hrtimer
interrupts and no timers expire on that CPU which results in RCU stalls and
other malfunctions.

Clear the flag along with some other less critical members of the hrtimer
cpu base to ensure starting from a clean state when a CPU is plugged in.

Thanks to Paul, Sebastian and Anna-Maria for their help to get down to the
root cause of that hard to reproduce heisenbug. Once understood it's
trivial and certainly justifies a brown paperbag.

Fixes: 41d2e494 ("hrtimer: Tune hrtimer_interrupt hang logic")
Reported-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Sewior <bigeasy@linutronix.de>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801261447590.2067@nanos
      d5421ea4
    • H. Peter Anvin's avatar
      x86: Mark hpa as a "Designated Reviewer" for the time being · 8a95b74d
      H. Peter Anvin authored 
      Due to some unfortunate events, I have not been directly involved in
the x86 kernel patch flow for a while now.  I have also not been able
to ramp back up by now like I had hoped to, and after reviewing what I
will need to work on both internally at Intel and elsewhere in the near
term, it is clear that I am not going to be able to ramp back up until
late 2018 at the very earliest.

It is not acceptable to not recognize that this load is currently
taken by Ingo and Thomas without my direct participation, so I mark
myself as R: (designated reviewer) rather than M: (maintainer) until
further notice.  This is in fact recognizing the de facto situation
for the past few years.

I have obviously no intention of going away, and I will do everything
within my power to improve Linux on x86 and x86 for Linux.  This,
however, puts credit where it is due and reflects a change of focus.

This patch also removes stale entries for portions of the x86
architecture which have not been maintained separately from arch/x86
for a long time.  If there is a reason to re-introduce them then that
can happen later.
Signed-off-by: default avatarH. Peter Anvin <h.peter.anvin@intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Bruce Schlobohm <bruce.schlobohm@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180125195934.5253-1-hpa@zytor.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      8a95b74d
  9. 26 Jan, 2018 13 commits
  11. 25 Jan, 2018 11 commits
    • Lyude Paul's avatar
      drm/nouveau: Move irq setup/teardown to pci ctor/dtor · 0fd189a9
      Lyude Paul authored 
      For a while we've been having issues with seemingly random interrupts
coming from nvidia cards when resuming them. Originally the fix for this
was thought to be just re-arming the MSI interrupt registers right after
re-allocating our IRQs, however it seems a lot of what we do is both
wrong and not even nessecary.

This was made apparent by what appeared to be a regression in the
mainline kernel that started introducing suspend/resume issues for
nouveau:

        a0c9259d (irq/matrix: Spread interrupts on allocation)

After this commit was introduced, we started getting interrupts from the
GPU before we actually re-allocated our own IRQ (see references below)
and assigned the IRQ handler. Investigating this turned out that the
problem was not with the commit, but the fact that nouveau even
free/allocates it's irqs before and after suspend/resume.

For starters: drivers in the linux kernel haven't had to handle
freeing/re-allocating their IRQs during suspend/resume cycles for quite
a while now. Nouveau seems to be one of the few drivers left that still
does this, despite the fact there's no reason we actually need to since
disabling interrupts from the device side should be enough, as the
kernel is already smart enough to know to disable host-side interrupts
for us before going into suspend. Since we were tearing down our IRQs by
hand however, that means there was a short period during resume where
interrupts could be received before we re-allocated our IRQ which would
lead to us getting an unhandled IRQ. Since we never handle said IRQ and
re-arm the interrupt registers, this would cause us to miss all of the
interrupts from the GPU and cause our init process to start timing out
on anything requiring interrupts.

So, since this whole setup/teardown every suspend/resume cycle is
useless anyway, move irq setup/teardown into the pci subdev's ctor/dtor
functions instead so they're only called at driver load and driver
unload. This should fix most of the issues with pending interrupts on
resume, along with getting suspend/resume for nouveau to work again.

As well, this probably means we can also just remove the msi rearm call
inside nvkm_pci_init(). But since our main focus here is to fix
suspend/resume before 4.15, we'll save that for a later patch.
Signed-off-by: default avatarLyude Paul <lyude@redhat.com>
Cc: Karol Herbst <kherbst@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
      0fd189a9
    • Nicolas Dichtel's avatar
      net: don't call update_pmtu unconditionally · f15ca723
      Nicolas Dichtel authored 
      Some dst_ops (e.g. md_dst_ops)) doesn't set this handler. It may result to:
"BUG: unable to handle kernel NULL pointer dereference at           (null)"

Let's add a helper to check if update_pmtu is available before calling it.

Fixes: 52a589d5 ("geneve: update skb dst pmtu on tx path")
Fixes: a93bf0ff ("vxlan: update skb dst pmtu on tx path")
CC: Roman Kapl <code@rkapl.cz>
CC: Xin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      f15ca723
    • Linus Torvalds's avatar
      Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm · 6e20630e
      Linus Torvalds authored 
      Pull KVM fixes from Radim Krčmář:
 "Fix races and a potential use after free in the s390 cmma migration
  code"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: add proper locking for CMMA migration bitmap
      6e20630e
    • Linus Torvalds's avatar
      Merge tag 'for-4.15-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux · 525273fb
      Linus Torvalds authored 
      Pull btrfs fix from David Sterba:
 "It's been reported recently that readdir can list stale entries under
  some conditions. Fix it."

* tag 'for-4.15-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix stale entries in readdir
      525273fb
    • Dan Streetman's avatar
      net: tcp: close sock if net namespace is exiting · 4ee806d5
      Dan Streetman authored 
      When a tcp socket is closed, if it detects that its net namespace is
exiting, close immediately and do not wait for FIN sequence.

For normal sockets, a reference is taken to their net namespace, so it will
never exit while the socket is open.  However, kernel sockets do not take a
reference to their net namespace, so it may begin exiting while the kernel
socket is still open.  In this case if the kernel socket is a tcp socket,
it will stay open trying to complete its close sequence.  The sock's dst(s)
hold a reference to their interface, which are all transferred to the
namespace's loopback interface when the real interfaces are taken down.
When the namespace tries to take down its loopback interface, it hangs
waiting for all references to the loopback interface to release, which
results in messages like:

unregister_netdevice: waiting for lo to become free. Usage count = 1

These messages continue until the socket finally times out and closes.
Since the net namespace cleanup holds the net_mutex while calling its
registered pernet callbacks, any new net namespace initialization is
blocked until the current net namespace finishes exiting.

After this change, the tcp socket notices the exiting net namespace, and
closes immediately, releasing its dst(s) and their reference to the
loopback interface, which lets the net namespace continue exiting.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=97811Signed-off-by: default avatarDan Streetman <ddstreet@canonical.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      4ee806d5
    • Peter Zijlstra's avatar
      perf/x86: Fix perf,x86,cpuhp deadlock · efe951d3
      Peter Zijlstra authored 
      More lockdep gifts, a 5-way lockup race:

	perf_event_create_kernel_counter()
	  perf_event_alloc()
	    perf_try_init_event()
	      x86_pmu_event_init()
		__x86_pmu_event_init()
		  x86_reserve_hardware()
 #0		    mutex_lock(&pmc_reserve_mutex);
		    reserve_ds_buffer()
 #1		      get_online_cpus()

	perf_event_release_kernel()
	  _free_event()
	    hw_perf_event_destroy()
	      x86_release_hardware()
 #0		mutex_lock(&pmc_reserve_mutex)
		release_ds_buffer()
 #1		  get_online_cpus()

 #1	do_cpu_up()
	  perf_event_init_cpu()
 #2	    mutex_lock(&pmus_lock)
 #3	    mutex_lock(&ctx->mutex)

	sys_perf_event_open()
	  mutex_lock_double()
 #3	    mutex_lock(ctx->mutex)
 #4	    mutex_lock_nested(ctx->mutex, 1);

	perf_try_init_event()
 #4	  mutex_lock_nested(ctx->mutex, 1)
	  x86_pmu_event_init()
	    intel_pmu_hw_config()
	      x86_add_exclusive()
 #0		mutex_lock(&pmc_reserve_mutex)

Fix it by using ordering constructs instead of locking.
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      efe951d3
    • Peter Zijlstra's avatar
      perf/core: Fix ctx::mutex deadlock · 0c7296ca
      Peter Zijlstra authored 
      Lockdep noticed the following 3-way lockup scenario:

	sys_perf_event_open()
	  perf_event_alloc()
	    perf_try_init_event()
 #0	      ctx = perf_event_ctx_lock_nested(1)
	      perf_swevent_init()
		swevent_hlist_get()
 #1		  mutex_lock(&pmus_lock)

	perf_event_init_cpu()
 #1	  mutex_lock(&pmus_lock)
 #2	  mutex_lock(&ctx->mutex)

	sys_perf_event_open()
	  mutex_lock_double()
 #2	   mutex_lock()
 #0	   mutex_lock_nested()

And while we need that perf_event_ctx_lock_nested() for HW PMUs such
that they can iterate the sibling list, trying to match it to the
available counters, the software PMUs need do no such thing. Exclude
them.

In particular the swevent triggers the above invertion, while the
tpevent PMU triggers a more elaborate one through their event_mutex.
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      0c7296ca
    • Peter Zijlstra's avatar
      perf/core: Fix another perf,trace,cpuhp lock inversion · 43fa87f7
      Peter Zijlstra authored 
      Lockdep noticed the following 3-way lockup race:

        perf_trace_init()
 #0       mutex_lock(&event_mutex)
          perf_trace_event_init()
            perf_trace_event_reg()
              tp_event->class->reg() := tracepoint_probe_register
 #1              mutex_lock(&tracepoints_mutex)
                  trace_point_add_func()
 #2                  static_key_enable()

 #2	do_cpu_up()
	  perf_event_init_cpu()
 #3	    mutex_lock(&pmus_lock)
 #4	    mutex_lock(&ctx->mutex)

	perf_ioctl()
 #4	  ctx = perf_event_ctx_lock()
	  _perf_iotcl()
	    ftrace_profile_set_filter()
 #0	      mutex_lock(&event_mutex)

Fudge it for now by noting that the tracepoint state does not depend
on the event <-> context relation. Ugly though :/
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      43fa87f7
    • Peter Zijlstra's avatar
      perf/core: Fix lock inversion between perf,trace,cpuhp · 82d94856
      Peter Zijlstra authored 
      Lockdep gifted us with noticing the following 4-way lockup scenario:

        perf_trace_init()
 #0       mutex_lock(&event_mutex)
          perf_trace_event_init()
            perf_trace_event_reg()
              tp_event->class->reg() := tracepoint_probe_register
 #1             mutex_lock(&tracepoints_mutex)
                  trace_point_add_func()
 #2                 static_key_enable()

 #2     do_cpu_up()
          perf_event_init_cpu()
 #3         mutex_lock(&pmus_lock)
 #4         mutex_lock(&ctx->mutex)

        perf_event_task_disable()
          mutex_lock(&current->perf_event_mutex)
 #4       ctx = perf_event_ctx_lock()
 #5       perf_event_for_each_child()

        do_exit()
          task_work_run()
            __fput()
              perf_release()
                perf_event_release_kernel()
 #4               mutex_lock(&ctx->mutex)
 #5               mutex_lock(&event->child_mutex)
                  free_event()
                    _free_event()
                      event->destroy() := perf_trace_destroy
 #0                     mutex_lock(&event_mutex);

Fix that by moving the free_event() out from under the locks.
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      82d94856
    • Dave Airlie's avatar
      Merge tag 'drm-misc-fixes-2018-01-24' of git://anongit.freedesktop.org/drm/drm-misc into drm-fixes · 7e3f8e91
      Dave Airlie authored 
      Two vc4 fixes that were applied in the last day.
One fixes a NULL dereference, and the other fixes
a flickering bug.

Cc: Eric Anholt <eric@anholt.net>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>

* tag 'drm-misc-fixes-2018-01-24' of git://anongit.freedesktop.org/drm/drm-misc:
  drm/vc4: Fix NULL pointer dereference in vc4_save_hang_state()
  drm/vc4: Flush the caches before the bin jobs, as well.
      7e3f8e91
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · 5b7d2796
      Linus Torvalds authored 
      Pull networking fixes from David Miller:

 1) Avoid negative netdev refcount in error flow of xfrm state add, from
    Aviad Yehezkel.

 2) Fix tcpdump decoding of IPSEC decap'd frames by filling in the
    ethernet header protocol field in xfrm{4,6}_mode_tunnel_input().
    From Yossi Kuperman.

 3) Fix a syzbot triggered skb_under_panic in pppoe having to do with
    failing to allocate an appropriate amount of headroom. From
    Guillaume Nault.

 4) Fix memory leak in vmxnet3 driver, from Neil Horman.

 5) Cure out-of-bounds packet memory access in em_nbyte EMATCH module,
    from Wolfgang Bumiller.

 6) Restrict what kinds of sockets can be bound to the KCM multiplexer
    and also disallow when another layer has attached to the socket and
    made use of sk_user_data. From Tom Herbert.

 7) Fix use before init of IOTLB in vhost code, from Jason Wang.

 8) Correct STACR register write bit definition in IBM emac driver, from
    Ivan Mikhaylov.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  net/ibm/emac: wrong bit is used for STA control register write
  net/ibm/emac: add 8192 rx/tx fifo size
  vhost: do not try to access device IOTLB when not initialized
  vhost: use mutex_lock_nested() in vhost_dev_lock_vqs()
  i40e: flower: check if TC offload is enabled on a netdev
  qed: Free reserved MR tid
  qed: Remove reserveration of dpi for kernel
  kcm: Check if sk_user_data already set in kcm_attach
  kcm: Only allow TCP sockets to be attached to a KCM mux
  net: sched: fix TCF_LAYER_LINK case in tcf_get_base_ptr
  net: sched: em_nbyte: don't add the data offset twice
  mlxsw: spectrum_router: Don't log an error on missing neighbor
  vmxnet3: repair memory leak
  ipv6: Fix getsockopt() for sockets with default IPV6_AUTOFLOWLABEL
  pppoe: take ->needed_headroom of lower device into account on xmit
  xfrm: fix boolean assignment in xfrm_get_type_offload
  xfrm: Fix eth_hdr(skb)->h_proto to reflect inner IP version
  xfrm: fix error flow in case of add state fails
  xfrm: Add SA to hardware at the end of xfrm_state_construct()
      5b7d2796
  13. 24 Jan, 2018 2 commits
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