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Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus
Jonathan writes:
Second round of IIO fixes for the 3.13 cycle.
2 fixes here.
* The gp2ap020a00f is a simple missing kconfig dependency.
* The hid sensors hub fix is a work around for an issue introduced by hardware
changes due to a certain large software vendor having an 'interesting'
interpretation of the specification and hence indexing some arrays from 1
rather than 0. The fix takes advantage of the logical min and max reading
facilities introduced by the precursor patch to figure out whether we have
a 0 indexed or 1 indexed device and to adjust appropriately. It also
drops a previous kconfig option that allowed this issue to be worked around
at build time.
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If __GFP_WAIT isn't set and we fail allocating, when we go
to drop the reference on the ctx, we will attempt to dereference
the NULL rq. Fix that.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If not, we could end up in the unfortunate situation where
we dereference a NULL pointer b/c we have cpuidle disabled.
This is the case when booting under Xen (which uses the
ACPI P/C states but disables the CPU idle driver) - and can
be easily reproduced when booting with cpuidle.off=1.
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8156db4a>] cpuidle_unregister_device+0x2a/0x90
.. snip..
Call Trace:
[<ffffffff813b15b4>] acpi_processor_power_exit+0x3c/0x5c
[<ffffffff813af0a9>] acpi_processor_stop+0x61/0xb6
[<ffffffff814215bf>] __device_release_driver+0fffff81421653>] device_release_driver+0x23/0x30
[<ffffffff81420ed8>] bus_remove_device+0x108/0x180
[<ffffffff8141d9d9>] device_del+0x129/0x1c0
[<ffffffff813cb4b0>] ? unregister_xenbus_watch+0x1f0/0x1f0
[<ffffffff8141da8e>] device_unregister+0x1e/0x60
[<ffffffff814243e9>] unregister_cpu+0x39/0x60
[<ffffffff81019e03>] arch_unregister_cpu+0x23/0x30
[<ffffffff813c3c51>] handle_vcpu_hotplug_event+0xc1/0xe0
[<ffffffff813cb4f5>] xenwatch_thread+0x45/0x120
[<ffffffff810af010>] ? abort_exclusive_wait+0xb0/0xb0
[<ffffffff8108ec42>] kthread+0xd2/0xf0
[<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180
[<ffffffff816ce17c>] ret_from_fork+0x7c/0xb0
[<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180
This problem also appears in 3.12 and could be a candidate for backport.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Enable MMC/SD on the Broadcom mobile platforms, and increase the block
minors from the default 8 to 16 (since the Broadcom board by default
has root on the 8th partition).
Signed-off-by: Olof Johansson <olof@lixom.net>
Cc: stable@vger.kernel.org # v3.12
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This enables a few more options on the sunxi defconfigs such that I can
use nfsroot to boot them (there is no local storage support yet). It
also enables PRINTK_TIME and tmpfs since it's a common distro requirement.
Signed-off-by: Olof Johansson <olof@lixom.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes
From Tony Lindgren:
Few more legacy booting vs device tree booting fixes that people
have noticed while booting things with device tree for things like
omap4 WLAN, smsc911x, and beagle audio. Hopefully this will be it
for the legacy booting vs device tree fixes for this -rc cycle.
* tag 'omap-for-v3.13/more-dt-regressions' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
ARM: dts: Fix the name of supplies for smsc911x shared by OMAP
ARM: OMAP2+: Powerdomain: Fix unchecked dereference of arch_pwrdm
ARM: dts: omap3-beagle: Add omap-twl4030 audio support
ARM: dts: omap4-sdp: Fix pin muxing for wl12xx
ARM: dts: omap4-panda-common: Fix pin muxing for wl12xx
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BeagleBone Black uses the TI CPSW ethernet controller, enable it in the
multi_v7_defconfig for testing coverage purposes.
Signed-off-by: Olof Johansson <olof@lixom.net>
Acked-by: Tony Lindgren <tony@atomide.com>
Cc: stable@vger.kernel.org # v3.12
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From Nicolas Ferre:
AT91: second round of fixes for 3.13
- reduce IP frequency for I2C on sama5d3
- missing aliases directive for USART3 on 9x5 family
- a PM symbol is missing if !CONFIG_PM
* tag 'at91-fixes' of git://github.com/at91linux/linux-at91:
ARM: at91: fixed unresolved symbol "at91_pm_set_standby" when built without CONFIG_PM
ARM: at91: add usart3 alias to dtsi
ARM: at91: sama5d3: reduce TWI internal clock frequency
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fixes
From Jason Cooper, mvebu DT fixes for v3.13:
- mvebu
- PCIe fixes now that we have test devices with more ports.
- fix access to coherency registers
* tag 'mvebu-dt-fixes-3.13' of git://git.infradead.org/linux-mvebu:
ARM: mvebu: re-enable PCIe on Armada 370 DB
ARM: mvebu: use the virtual CPU registers to access coherency registers
ARM: mvebu: fix second and third PCIe unit of Armada XP mv78260
ARM: mvebu: second PCIe unit of Armada XP mv78230 is only x1 capable
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git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes
From Tony Lindgren:
Some omap related fixes that have come up with people moving to device
tree only based booting for omap2+.
The series contains a handful of fixes for the igep boards as they were
one of the first omap3 boards to jump over completely to device tree
based booting. So these can be considered regressions compared to
booting igep in legacy mode with board files in v3.12.
Also included are few other device tree vs legacy booting regressions:
- yet more missing omap3 .dtsi entries that have showed up booting
various boards with device tree only
- n900 eMMC device tree fix
- fixes for beagle USB EHCI
- two fixes to make omap2420 MMC work
As we're moving omap2+ to be device tree only for v3.14, I'd like to
have v3.13 work equally well for legacy based booting and device tree
based booting. So there will be likely few more device tree related
booting patches trickling in.
This series also includes a regression fix for the omap timer posted
mode that may wrongly stay on from the bootloader for some SoCs.
* tag 'omap-for-v3.13/fixes-against-rc1-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
mmc: omap: Fix I2C dependency and make driver usable with device tree
mmc: omap: Fix DMA configuration to not rely on device id
ARM: dts: omap3-beagle: Fix USB host on beagle boards (for 3.13)
ARM: dts: omap3-igep0020: name twl4030 VPLL2 regulator as vdds_dsi
ARM: dts: AM33XX IGEP0033: add USB support
ARM: dts: AM33XX BASE0033: add 32KBit EEPROM support
ARM: dts: AM33XX BASE0033: add pinmux and user led support
ARM: dts: AM33XX BASE0033: add pinmux and hdmi node to enable display
ARM: dts: omap3-igep0020: Add pinmuxing for DVI output
ARM: dts: omap3-igep0020: Add pinmux setup for i2c devices
ARM: dts: omap3-igep: Update to use the TI AM/DM37x processor
ARM: dts: omap3-igep: Add support for LBEE1USJYC WiFi connected to SDIO
ARM: dts: omap3-igep: Fix bus-width for mmc1
ARM: OMAP2+: dss-common: change IGEP's DVI DDC i2c bus
ARM: OMAP2+: Disable POSTED mode for errata i103 and i767
ARM: OMAP2+: Fix eMMC on n900 with device tree
ARM: OMAP2+: Add fixed regulator to omap2plus_defconfig
ARM: OMAP2+: Fix more missing data for omap3.dtsi file
Signed-off-by: Olof Johansson <olof@lixom.net>
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All of the rcutorture scripts has the usual GPL header, which contains
a long-obsolete postal address for FSF. To avoid the need to track the
FSF office's movements, this commit substitutes the URL where GPL may
be found.
Reported-by: Greg KH <gregkh@linuxfoundation.org>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The output of the rcutorture scripts often requires interpretation, so
this commit simplifies this interpretation by tagging messages as
BUGs (colored red) or WARNINGs (colored yellow).
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Repeatedly running a given test, for example, by repeating the name
as in "--configs "TREE08 TREE08 TREE08" records the results only of
the last run of this test. This is because the earlier results are
overwritten by the later results.
This commit therefore checks for earlier results, using numbered
file extensions to distinguish multiple runs. The earlier example
would therefore create directories TREE01, TREE01.2, and TREE01.3.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The commit causes kvm.sh to invoke kvm-recheck.sh at the end of each
run, and causes kvm-recheck.sh to print only the name of the test, not
the full path to the corresponding Kconfig file.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The TREE08 Kconfig fragment does not enable tracing, which is appropriate
for its test case. However, this can be inconvenient in cases where
TREE08 locates RCU bugs. This commit therefore adds a TREE08-T that
differs from TREE08 only in enabling CONFIG_RCU_TRACE.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit adds the --kmake-arg to kvm.sh, which allows passing in
things like "V=1" to see the build commands, as well as enabling the
CROSS_COMPILE= make macro used for cross-building.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit adds the --no-initrd argument to kvm.sh, which permits
initrd to be contained in a root partition specified by the --bootargs
argument. Without --no-initrd, the kernel build expects an initrd
directory in the same rcutorture directory that contains bin and configs.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commits adds the --qemu-args argument to kvm.sh that is required
to pass boot devices down through to qemu.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit allows easy specification of trace_event lists, among other
things.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit adds --buildonly, which does the builds specified by the
--configs argument, but does not boot or test the resulting kernels.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Don't grab the configuration fragment from the configs directory because
it might well have been changed since the test was run. Instead, use
the ConfigFragment file that was placed in the results directory.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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As it stands, the default kernel boot parameters generated from
the Kconfig fragment will override any supplied with the .boot
file that can optionally accompany a Kconfig fragment. Rearrange
ordering to permit the specific .boot arguments to override those
generated by analyzing the Kconfig fragment.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit expands the checks for what architecture is running to generate
additional qemu-system- commands, then uses the resulting qemu-system-
command name to choose different qemu arguments as needed for different
architectures.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The --rcu-kvm argument was intended to allow the scripts to live in
an alternate location. Unfortunately, this prevents the kvm.sh script
from using common functions until after it finished parsing arguments,
because it doesn't know where to find them until then. However, "cp -a"
and "ln -s" work pretty well, so lack of an --rcu-kvm argument can be
easily worked around.
This commit therefore removes this argument.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The qemu -name argument doesn't seem to be useful in this environment,
so this commit removes it.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The task of working out which flavor of qemu to use gets more complex
as more types of CPUs are supported. Adding Power makes three in addition
to 32-bit and 64-bit x86, so it is time to pull this out into a function.
This commit therefore creates an identify_qemu function and also adds
a --qemu-cmd command-line argument for the inevitable case where the
identify_qemu cannot figure it out.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The commit uses configcheck.sh from within configinit.sh, replacing the
imperfect inline expansion that was there before.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit drops no-longer-needed diagnostics from the output. Some of
them are retained in logfiles, in case they are ever needed.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The TINY_RCU test cases were first put in place many years ago, and have
been incrementally modified rather than being reworked. This commit
therefore completes a long-overdue reworking of the TINY_RCU test cases.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The TREE_RCU test cases were first put in place many years ago, and have
been incrementally modified rather than being reworked. This commit
therefore completes a long-overdue reworking of the TREE_RCU test cases.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Use .boot facility to ease inclusion of SRCU into automated testing.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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The v3.12 version of the kernel added the CONFIG_NO_HZ_FULL_SYSIDLE
Kconfig parameter, so this commit adds a version transition at that
point.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Some Kconfig fragments require rcutorture module parameters to
do optimal testing, for example, a configuration for SRCU would
need rcutorture.torture_type=srcu. This commit therefore adds a
per-Kconfig-fragment boot-parameter capability.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Different Kconfig parameters apply to different kernel versions, as
do different rcutorture module parameters. This commit allows the
rcutorture test scripts to adjust for different kernel versions.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Allow datestamp to be specified to allow tests to be broken up and run
in parallel.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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This commit adds the test framework that I used to test RCU under KVM.
This consists of a group of scripts and Kconfig fragments.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
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Some RCU bugs have been specific to the layout of the rcu_node tree,
but RCU will silently adjust the tree at boot time if appropriate.
This obscures valuable debugging information, so print a message when
this happens.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The srcu_barrier() docbook header left out the "sp" argument, so this
commit adds that argument's docbook text.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The current task-level idle entry/exit code forces an entry/exit on
each call, regardless of the nesting level. This commit therefore
properly accounts for nesting.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
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Dave Jones got the following lockdep splat:
> ======================================================
> [ INFO: possible circular locking dependency detected ]
> 3.12.0-rc3+ #92 Not tainted
> -------------------------------------------------------
> trinity-child2/15191 is trying to acquire lock:
> (&rdp->nocb_wq){......}, at: [<ffffffff8108ff43>] __wake_up+0x23/0x50
>
> but task is already holding lock:
> (&ctx->lock){-.-...}, at: [<ffffffff81154c19>] perf_event_exit_task+0x109/0x230
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #3 (&ctx->lock){-.-...}:
> [<ffffffff810cc243>] lock_acquire+0x93/0x200
> [<ffffffff81733f90>] _raw_spin_lock+0x40/0x80
> [<ffffffff811500ff>] __perf_event_task_sched_out+0x2df/0x5e0
> [<ffffffff81091b83>] perf_event_task_sched_out+0x93/0xa0
> [<ffffffff81732052>] __schedule+0x1d2/0xa20
> [<ffffffff81732f30>] preempt_schedule_irq+0x50/0xb0
> [<ffffffff817352b6>] retint_kernel+0x26/0x30
> [<ffffffff813eed04>] tty_flip_buffer_push+0x34/0x50
> [<ffffffff813f0504>] pty_write+0x54/0x60
> [<ffffffff813e900d>] n_tty_write+0x32d/0x4e0
> [<ffffffff813e5838>] tty_write+0x158/0x2d0
> [<ffffffff811c4850>] vfs_write+0xc0/0x1f0
> [<ffffffff811c52cc>] SyS_write+0x4c/0xa0
> [<ffffffff8173d4e4>] tracesys+0xdd/0xe2
>
> -> #2 (&rq->lock){-.-.-.}:
> [<ffffffff810cc243>] lock_acquire+0x93/0x200
> [<ffffffff81733f90>] _raw_spin_lock+0x40/0x80
> [<ffffffff810980b2>] wake_up_new_task+0xc2/0x2e0
> [<ffffffff81054336>] do_fork+0x126/0x460
> [<ffffffff81054696>] kernel_thread+0x26/0x30
> [<ffffffff8171ff93>] rest_init+0x23/0x140
> [<ffffffff81ee1e4b>] start_kernel+0x3f6/0x403
> [<ffffffff81ee1571>] x86_64_start_reservations+0x2a/0x2c
> [<ffffffff81ee1664>] x86_64_start_kernel+0xf1/0xf4
>
> -> #1 (&p->pi_lock){-.-.-.}:
> [<ffffffff810cc243>] lock_acquire+0x93/0x200
> [<ffffffff8173419b>] _raw_spin_lock_irqsave+0x4b/0x90
> [<ffffffff810979d1>] try_to_wake_up+0x31/0x350
> [<ffffffff81097d62>] default_wake_function+0x12/0x20
> [<ffffffff81084af8>] autoremove_wake_function+0x18/0x40
> [<ffffffff8108ea38>] __wake_up_common+0x58/0x90
> [<ffffffff8108ff59>] __wake_up+0x39/0x50
> [<ffffffff8110d4f8>] __call_rcu_nocb_enqueue+0xa8/0xc0
> [<ffffffff81111450>] __call_rcu+0x140/0x820
> [<ffffffff81111b8d>] call_rcu+0x1d/0x20
> [<ffffffff81093697>] cpu_attach_domain+0x287/0x360
> [<ffffffff81099d7e>] build_sched_domains+0xe5e/0x10a0
> [<ffffffff81efa7fc>] sched_init_smp+0x3b7/0x47a
> [<ffffffff81ee1f4e>] kernel_init_freeable+0xf6/0x202
> [<ffffffff817200be>] kernel_init+0xe/0x190
> [<ffffffff8173d22c>] ret_from_fork+0x7c/0xb0
>
> -> #0 (&rdp->nocb_wq){......}:
> [<ffffffff810cb7ca>] __lock_acquire+0x191a/0x1be0
> [<ffffffff810cc243>] lock_acquire+0x93/0x200
> [<ffffffff8173419b>] _raw_spin_lock_irqsave+0x4b/0x90
> [<ffffffff8108ff43>] __wake_up+0x23/0x50
> [<ffffffff8110d4f8>] __call_rcu_nocb_enqueue+0xa8/0xc0
> [<ffffffff81111450>] __call_rcu+0x140/0x820
> [<ffffffff81111bb0>] kfree_call_rcu+0x20/0x30
> [<ffffffff81149abf>] put_ctx+0x4f/0x70
> [<ffffffff81154c3e>] perf_event_exit_task+0x12e/0x230
> [<ffffffff81056b8d>] do_exit+0x30d/0xcc0
> [<ffffffff8105893c>] do_group_exit+0x4c/0xc0
> [<ffffffff810589c4>] SyS_exit_group+0x14/0x20
> [<ffffffff8173d4e4>] tracesys+0xdd/0xe2
>
> other info that might help us debug this:
>
> Chain exists of:
> &rdp->nocb_wq --> &rq->lock --> &ctx->lock
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&ctx->lock);
> lock(&rq->lock);
> lock(&ctx->lock);
> lock(&rdp->nocb_wq);
>
> *** DEADLOCK ***
>
> 1 lock held by trinity-child2/15191:
> #0: (&ctx->lock){-.-...}, at: [<ffffffff81154c19>] perf_event_exit_task+0x109/0x230
>
> stack backtrace:
> CPU: 2 PID: 15191 Comm: trinity-child2 Not tainted 3.12.0-rc3+ #92
> ffffffff82565b70 ffff880070c2dbf8 ffffffff8172a363 ffffffff824edf40
> ffff880070c2dc38 ffffffff81726741 ffff880070c2dc90 ffff88022383b1c0
> ffff88022383aac0 0000000000000000 ffff88022383b188 ffff88022383b1c0
> Call Trace:
> [<ffffffff8172a363>] dump_stack+0x4e/0x82
> [<ffffffff81726741>] print_circular_bug+0x200/0x20f
> [<ffffffff810cb7ca>] __lock_acquire+0x191a/0x1be0
> [<ffffffff810c6439>] ? get_lock_stats+0x19/0x60
> [<ffffffff8100b2f4>] ? native_sched_clock+0x24/0x80
> [<ffffffff810cc243>] lock_acquire+0x93/0x200
> [<ffffffff8108ff43>] ? __wake_up+0x23/0x50
> [<ffffffff8173419b>] _raw_spin_lock_irqsave+0x4b/0x90
> [<ffffffff8108ff43>] ? __wake_up+0x23/0x50
> [<ffffffff8108ff43>] __wake_up+0x23/0x50
> [<ffffffff8110d4f8>] __call_rcu_nocb_enqueue+0xa8/0xc0
> [<ffffffff81111450>] __call_rcu+0x140/0x820
> [<ffffffff8109bc8f>] ? local_clock+0x3f/0x50
> [<ffffffff81111bb0>] kfree_call_rcu+0x20/0x30
> [<ffffffff81149abf>] put_ctx+0x4f/0x70
> [<ffffffff81154c3e>] perf_event_exit_task+0x12e/0x230
> [<ffffffff81056b8d>] do_exit+0x30d/0xcc0
> [<ffffffff810c9af5>] ? trace_hardirqs_on_caller+0x115/0x1e0
> [<ffffffff810c9bcd>] ? trace_hardirqs_on+0xd/0x10
> [<ffffffff8105893c>] do_group_exit+0x4c/0xc0
> [<ffffffff810589c4>] SyS_exit_group+0x14/0x20
> [<ffffffff8173d4e4>] tracesys+0xdd/0xe2
The underlying problem is that perf is invoking call_rcu() with the
scheduler locks held, but in NOCB mode, call_rcu() will with high
probability invoke the scheduler -- which just might want to use its
locks. The reason that call_rcu() needs to invoke the scheduler is
to wake up the corresponding rcuo callback-offload kthread, which
does the job of starting up a grace period and invoking the callbacks
afterwards.
One solution (championed on a related problem by Lai Jiangshan) is to
simply defer the wakeup to some point where scheduler locks are no longer
held. Since we don't want to unnecessarily incur the cost of such
deferral, the task before us is threefold:
1. Determine when it is likely that a relevant scheduler lock is held.
2. Defer the wakeup in such cases.
3. Ensure that all deferred wakeups eventually happen, preferably
sooner rather than later.
We use irqs_disabled_flags() as a proxy for relevant scheduler locks
being held. This works because the relevant locks are always acquired
with interrupts disabled. We may defer more often than needed, but that
is at least safe.
The wakeup deferral is tracked via a new field in the per-CPU and
per-RCU-flavor rcu_data structure, namely ->nocb_defer_wakeup.
This flag is checked by the RCU core processing. The __rcu_pending()
function now checks this flag, which causes rcu_check_callbacks()
to initiate RCU core processing at each scheduling-clock interrupt
where this flag is set. Of course this is not sufficient because
scheduling-clock interrupts are often turned off (the things we used to
be able to count on!). So the flags are also checked on entry to any
state that RCU considers to be idle, which includes both NO_HZ_IDLE idle
state and NO_HZ_FULL user-mode-execution state.
This approach should allow call_rcu() to be invoked regardless of what
locks you might be holding, the key word being "should".
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
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It is all too easy to forget that wait_event() does not necessarily
imply a full memory barrier. The case where it does not is where the
condition transitions to true just as wait_event() starts execution.
This is actually a feature: The standard use of wait_event() involves
locking, in which case the locks provide the needed ordering (you hold a
lock across the wake_up() and acquire that same lock after wait_event()
returns).
Given that I did forget that wait_event() does not necessarily imply a
full memory barrier in one case, this commit fixes that case. This commit
also adds comments calling out the placement of existing memory barriers
relied on by wait_event() calls.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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When an RCU CPU stall warning occurs, the CPU invokes resched_cpu() on
itself. This can help move the grace period forward in some situations,
but it would be even better to do this -before- the RCU CPU stall warning.
This commit therefore causes resched_cpu() to be called every five jiffies
once the system is halfway to an RCU CPU stall warning.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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'asoc/fix/fsl', 'asoc/fix/kirkwood', 'asoc/fix/omap', 'asoc/fix/rcar', 'asoc/fix/wm8731' and 'asoc/fix/wm8990' into asoc-linus
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