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  1. 17 Mar, 2008 5 commits
    • Christian Borntraeger's avatar
      virtio: fix race in enable_cb · 4265f161
      Christian Borntraeger authored 
      There is a race in virtio_net, dealing with disabling/enabling the callback.
I saw the following oops:

kernel BUG at /space/kvm/drivers/virtio/virtio_ring.c:218!
illegal operation: 0001 [#1] SMP
Modules linked in: sunrpc dm_mod
CPU: 2 Not tainted 2.6.25-rc1zlive-host-10623-gd358142-dirty #99
Process swapper (pid: 0, task: 000000000f85a610, ksp: 000000000f873c60)
Krnl PSW : 0404300180000000 00000000002b81a6 (vring_disable_cb+0x16/0x20)
           R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3
Krnl GPRS: 0000000000000001 0000000000000001 0000000010005800 0000000000000001
           000000000f3a0900 000000000f85a610 0000000000000000 0000000000000000
           0000000000000000 000000000f870000 0000000000000000 0000000000001237
           000000000f3a0920 000000000010ff74 00000000002846f6 000000000fa0bcd8
Krnl Code: 00000000002b819a: a7110001           tmll    %r1,1
           00000000002b819e: a7840004           brc     8,2b81a6
           00000000002b81a2: a7f40001           brc     15,2b81a4
          >00000000002b81a6: a51b0001           oill    %r1,1
           00000000002b81aa: 40102000           sth     %r1,0(%r2)
           00000000002b81ae: 07fe               bcr     15,%r14
           00000000002b81b0: eb7ff0380024       stmg    %r7,%r15,56(%r15)
           00000000002b81b6: a7f13e00           tmll    %r15,15872
Call Trace:
([<000000000fa0bcd0>] 0xfa0bcd0)
 [<00000000002b8350>] vring_interrupt+0x5c/0x6c
 [<000000000010ab08>] do_extint+0xb8/0xf0
 [<0000000000110716>] ext_no_vtime+0x16/0x1a
 [<0000000000107e72>] cpu_idle+0x1c2/0x1e0

The problem can be triggered with a high amount of host->guest traffic.
I think its the following race:

poll says netif_rx_complete
poll calls enable_cb
enable_cb opens the interrupt mask
a new packet comes, an interrupt is triggered----\
enable_cb sees that there is more work           |
enable_cb disables the interrupt                 |
       .                                         V
       .                            interrupt is delivered
       .                            skb_recv_done does atomic napi test, ok
 some waiting                       disable_cb is called->check fails->bang!
       .
poll would do napi check
poll would do disable_cb

The fix is to let enable_cb not disable the interrupt again, but expect the
caller to do the cleanup if it returns false. In that case, the interrupt is
only disabled, if the napi test_set_bit was successful.
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cleaned up doco)
      4265f161
    • Amit Shah's avatar
      virtio: Enable netpoll interface for netconsole logging · da74e89d
      Amit Shah authored 
      Add a new poll_controller handler that the netpoll interface needs.

This enables netconsole logging from a kvm guest over the virtio
net interface.
Signed-off-by: default avatarAmit Shah <amitshah@gmx.net>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      da74e89d
    • Rusty Russell's avatar
      virtio: handle > 2 billion page balloon targets · bdc1681c
      Rusty Russell authored 
      If the host asks for a huge target towards_target() can overflow, and
we up oops as we try to release more pages than we have.  The simple
fix is to use a 64-bit value.
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      bdc1681c
    • Jeremy Katz's avatar
      virtio: Fix sysfs bits to have proper block symlink · c4839346
      Jeremy Katz authored 
      Fix up so that the virtio_blk devices in sysfs link correctly to their
block device.  This then allows them to be detected by hal, etc
Signed-off-by: default avatarJeremy Katz <katzj@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      c4839346
    • Anthony Liguori's avatar
      virtio: Use spin_lock_irqsave/restore for virtio-pci · 27ebe308
      Anthony Liguori authored 
      virtio-pci acquires its spin lock in an interrupt context so it's necessary
to use spin_lock_irqsave/restore variants.  This patch fixes guest SMP when
using virtio devices in KVM.
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      27ebe308
  3. 16 Mar, 2008 20 commits
  5. 15 Mar, 2008 10 commits
    • Linus Torvalds's avatar
      ACPI: Remove ACPI_CUSTOM_DSDT_INITRD option · 9a9e0d68
      Linus Torvalds authored 
      This essentially reverts commit 71fc47a9
("ACPI: basic initramfs DSDT override support"), because the code simply
isn't ready.

It did ugly things to the init sequence to populate the rootfs image
early, but that just ended up showing other problems with the whole
approach.  The fact is, the VFS layer simply isn't initialized this
early, and the relevant ACPI code should either run much later, or this
shouldn't be done at all.

For 2.6.25, we'll just pick the latter option.  We can revisit this
concept later if necessary.

Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Tilman Schmidt <tilman@imap.cc>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Eric Piel <eric.piel@tremplin-utc.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Markus Gaugusch <dsdt@gaugusch.at>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9a9e0d68
    • Roel Kluin's avatar
      tifm_sd: DATA_CARRY is not boolean in tifm_sd_transfer_data() · ce636452
      Roel Kluin authored 
      DATA_CARRY is not boolean
Signed-off-by: default avatarRoel Kluin <12o3l@tiscali.nl>
Signed-off-by: default avatarPierre Ossman <drzeus@drzeus.cx>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ce636452
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 · afbf331e
      Linus Torvalds authored 
      * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  [NET]: Fix tbench regression in 2.6.25-rc1
      afbf331e
    • Ingo Molnar's avatar
      sched: simplify sched_slice() · 6a6029b8
      Ingo Molnar authored 
      Use the existing calc_delta_mine() calculation for sched_slice(). This
saves a divide and simplifies the code because we share it with the
other /cfs_rq->load users.

It also improves code size:

      text    data     bss     dec     hex filename
     42659    2740     144   45543    b1e7 sched.o.before
     42093    2740     144   44977    afb1 sched.o.after
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      6a6029b8
    • Ingo Molnar's avatar
      sched: fix fair sleepers · e22ecef1
      Ingo Molnar authored 
      Fair sleepers need to scale their latency target down by runqueue
weight. Otherwise busy systems will gain ever larger sleep bonus.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      e22ecef1
    • Peter Zijlstra's avatar
      sched: fix overload performance: buddy wakeups · aa2ac252
      Peter Zijlstra authored 
      Currently we schedule to the leftmost task in the runqueue. When the
runtimes are very short because of some server/client ping-pong,
especially in over-saturated workloads, this will cycle through all
tasks trashing the cache.

Reduce cache trashing by keeping dependent tasks together by running
newly woken tasks first. However, by not running the leftmost task first
we could starve tasks because the wakee can gain unlimited runtime.

Therefore we only run the wakee if its within a small
(wakeup_granularity) window of the leftmost task. This preserves
fairness, but does alternate server/client task groups.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      aa2ac252
    • Ingo Molnar's avatar
      sched: fix calc_delta_mine() · 27d11726
      Ingo Molnar authored 
      lw->weight can be 0 for a short time during bootup.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      27d11726
    • Ingo Molnar's avatar
      sched: fix update_load_add()/sub() · e89996ae
      Ingo Molnar authored 
      Clear the cached inverse value when updating load. This is needed for
calc_delta_mine() to work correctly when using the rq load.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      e89996ae
    • Peter Zijlstra's avatar
      sched: min_vruntime fix · 3fe69747
      Peter Zijlstra authored 
      Current min_vruntime tracking is incorrect and will cause serious
problems when we don't run the leftmost task for some reason.

min_vruntime does two things; 1) it's used to determine a forward
direction when the u64 vruntime wraps, 2) it's used to track the
leftmost vruntime to position newly enqueued tasks from.

The current logic advances min_vruntime whenever the current task's
vruntime advance. Because the current task may pass the leftmost task
still waiting we're failing the second goal. This causes new tasks to be
placed too far ahead and thus penalizes their runtime.

Fix this by making min_vruntime the min_vruntime of the waiting tasks by
tracking it in enqueue/dequeue, and compare against current's vruntime
to obtain the absolute minimum when placing new tasks.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      3fe69747
    • Hiroshi Shimamoto's avatar
      sched: fix race in schedule() · 0e1f3483
      Hiroshi Shimamoto authored 
      Fix a hard to trigger crash seen in the -rt kernel that also affects
the vanilla scheduler.

There is a race condition between schedule() and some dequeue/enqueue
functions; rt_mutex_setprio(), __setscheduler() and sched_move_task().

When scheduling to idle, idle_balance() is called to pull tasks from
other busy processor. It might drop the rq lock. It means that those 3
functions encounter on_rq=0 and running=1. The current task should be
put when running.

Here is a possible scenario:

   CPU0                               CPU1
    |                              schedule()
    |                              ->deactivate_task()
    |                              ->idle_balance()
    |                              -->load_balance_newidle()
rt_mutex_setprio()                     |
    |                              --->double_lock_balance()
    *get lock                          *rel lock
    * on_rq=0, ruuning=1               |
    * sched_class is changed           |
    *rel lock                          *get lock
    :                                  |
                                       :
                                   ->put_prev_task_rt()
                                   ->pick_next_task_fair()
                                       => panic

The current process of CPU1(P1) is scheduling. Deactivated P1, and the
scheduler looks for another process on other CPU's runqueue because CPU1
will be idle. idle_balance(), load_balance_newidle() and
double_lock_balance() are called and double_lock_balance() could drop
the rq lock. On the other hand, CPU0 is trying to boost the priority of
P1. The result of boosting only P1's prio and sched_class are changed to
RT. The sched entities of P1 and P1's group are never put. It makes
cfs_rq invalid, because the cfs_rq has curr and no leaf, but
pick_next_task_fair() is called, then the kernel panics.
Signed-off-by: default avatarHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      0e1f3483
  7. 14 Mar, 2008 3 commits
  9. 13 Mar, 2008 2 commits
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