While debugging an issue with excessive softirq usage, I encountered the
following note in commit 3e339b5dae ("softirq: Use hotplug thread
infrastructure"):
[ paulmck: Call rcu_note_context_switch() with interrupts enabled. ]
...but despite this note, the patch still calls RCU with IRQs disabled.
This seemingly innocuous change caused a significant regression in softirq
CPU usage on the sending side of a large TCP transfer (~1 GB/s): when
introducing 0.01% packet loss, the softirq usage would jump to around 25%,
spiking as high as 50%. Before the change, the usage would never exceed 5%.
Moving the call to rcu_note_context_switch() after the cond_sched() call,
as it was originally before the hotplug patch, completely eliminated this
problem.
Signed-off-by: Calvin Owens <calvinowens@fb.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The 48a7639ce8 ("rcu: Make callers awaken grace-period kthread")
removed the irq_work_queue(), so the TREE_RCU doesn't need
irq work any more. This commit therefore updates RCU's Kconfig and
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The rcu_barrier() no-callbacks check for no-CBs CPUs has race conditions.
It checks a given CPU's lists of callbacks, and if all three no-CBs lists
are empty, ignores that CPU. However, these three lists could potentially
be empty even when callbacks are present if the check executed just as
the callbacks were being moved from one list to another. It turns out
that recent versions of rcutorture can spot this race.
This commit plugs this hole by consolidating the per-list counts of
no-CBs callbacks into a single count, which is incremented before
the corresponding callback is posted and after it is invoked. Then
rcu_barrier() checks this single count to reliably determine whether
the corresponding CPU has no-CBs callbacks.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Commit b2c4623dcd ("rcu: More on deadlock between CPU hotplug and expedited
grace periods") introduced another problem that can easily be reproduced by
starting/stopping cpus in a loop.
E.g.:
for i in `seq 5000`; do
echo 1 > /sys/devices/system/cpu/cpu1/online
echo 0 > /sys/devices/system/cpu/cpu1/online
done
Will result in:
INFO: task /cpu_start_stop:1 blocked for more than 120 seconds.
Call Trace:
([<00000000006a028e>] __schedule+0x406/0x91c)
[<0000000000130f60>] cpu_hotplug_begin+0xd0/0xd4
[<0000000000130ff6>] _cpu_up+0x3e/0x1c4
[<0000000000131232>] cpu_up+0xb6/0xd4
[<00000000004a5720>] device_online+0x80/0xc0
[<00000000004a57f0>] online_store+0x90/0xb0
...
And a deadlock.
Problem is that if the last ref in put_online_cpus() can't get the
cpu_hotplug.lock the puts_pending count is incremented, but a sleeping
active_writer might never be woken up, therefore never exiting the loop in
cpu_hotplug_begin().
This fix removes puts_pending and turns refcount into an atomic variable. We
also introduce a wait queue for the active_writer, to avoid possible races and
use-after-free. There is no need to take the lock in put_online_cpus() anymore.
Can't reproduce it with this fix.
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
For RCU in UP, context-switch = QS = GP, thus we can force a
context-switch when any call_rcu_[bh|sched]() is happened on idle_task.
After doing so, rcu_idle/irq_enter/exit() are useless, so we can simply
make these functions empty.
More important, this change does not change the functionality logically.
Note: raise_softirq(RCU_SOFTIRQ)/rcu_sched_qs() in rcu_idle_enter() and
outmost rcu_irq_exit() will have to wake up the ksoftirqd
(due to in_interrupt() == 0).
Before this patch After this patch:
call_rcu_sched() in idle; call_rcu_sched() in idle
set resched
do other stuffs; do other stuffs
outmost rcu_irq_exit() outmost rcu_irq_exit() (empty function)
(or rcu_idle_enter()) (or rcu_idle_enter(), also empty function)
start to resched. (see above)
rcu_sched_qs() rcu_sched_qs()
QS,and GP and advance cb QS,and GP and advance cb
wake up the ksoftirqd wake up the ksoftirqd
set resched
resched to ksoftirqd (or other) resched to ksoftirqd (or other)
These two code patches are almost the same.
Size changed after patched:
size kernel/rcu/tiny-old.o kernel/rcu/tiny-patched.o
text data bss dec hex filename
3449 206 8 3663 e4f kernel/rcu/tiny-old.o
2406 144 8 2558 9fe kernel/rcu/tiny-patched.o
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Despite what the comment says, it is only softirqs that are disabled,
not interrupts. This commit therefore fixes the comment.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Let's start assuming that something in the idle loop posts a callback,
and scheduling-clock interrupt occurs:
1. The system is idle and stays that way, no runnable tasks.
2. Scheduling-clock interrupt occurs, rcu_check_callbacks() is called
as result, which in turn calls rcu_is_cpu_rrupt_from_idle().
3. rcu_is_cpu_rrupt_from_idle() reports the CPU was interrupted from
idle, which results in rcu_sched_qs() call, which does a
raise_softirq(RCU_SOFTIRQ).
4. Upon return from interrupt, rcu_irq_exit() is invoked, which calls
rcu_idle_enter_common(), which in turn calls rcu_sched_qs() again,
which does another raise_softirq(RCU_SOFTIRQ).
5. The softirq happens shortly and invokes rcu_process_callbacks(),
which invokes __rcu_process_callbacks().
6. So now callbacks can be invoked. At least they can be if
->donetail has been updated. Which it will have been because
rcu_sched_qs() invokes rcu_qsctr_help().
In the described scenario rcu_sched_qs() and raise_softirq(RCU_SOFTIRQ)
get called twice in steps 3 and 4. This redundancy could be eliminated
by removing rcu_is_cpu_rrupt_from_idle() function.
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The x86 architecture has multiple types of NMI-like interrupts: real
NMIs, machine checks, and, for some values of NMI-like, debugging
and breakpoint interrupts. These interrupts can nest inside each
other. Andy Lutomirski is adding RCU support to these interrupts,
so rcu_nmi_enter() and rcu_nmi_exit() must now correctly handle nesting.
This commit therefore introduces nesting, using a clever NMI-coordination
algorithm suggested by Andy. The trick is to atomically increment
->dynticks (if needed) before manipulating ->dynticks_nmi_nesting on entry
(and, accordingly, after on exit). In addition, ->dynticks_nmi_nesting
is incremented by one if ->dynticks was incremented and by two otherwise.
This means that when rcu_nmi_exit() sees ->dynticks_nmi_nesting equal
to one, it knows that ->dynticks must be atomically incremented.
This NMI-coordination algorithms has been validated by the following
Promela model:
------------------------------------------------------------------------
/*
* Promela model for Andy Lutomirski's suggested change to rcu_nmi_enter()
* that allows nesting.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, you can access it online at
* http://www.gnu.org/licenses/gpl-2.0.html.
*
* Copyright IBM Corporation, 2014
*
* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
*/
byte dynticks_nmi_nesting = 0;
byte dynticks = 0;
/*
* Promela verision of rcu_nmi_enter().
*/
inline rcu_nmi_enter()
{
byte incby;
byte tmp;
incby = BUSY_INCBY;
assert(dynticks_nmi_nesting >= 0);
if
:: (dynticks & 1) == 0 ->
atomic {
dynticks = dynticks + 1;
}
assert((dynticks & 1) == 1);
incby = 1;
:: else ->
skip;
fi;
tmp = dynticks_nmi_nesting;
tmp = tmp + incby;
dynticks_nmi_nesting = tmp;
assert(dynticks_nmi_nesting >= 1);
}
/*
* Promela verision of rcu_nmi_exit().
*/
inline rcu_nmi_exit()
{
byte tmp;
assert(dynticks_nmi_nesting > 0);
assert((dynticks & 1) != 0);
if
:: dynticks_nmi_nesting != 1 ->
tmp = dynticks_nmi_nesting;
tmp = tmp - BUSY_INCBY;
dynticks_nmi_nesting = tmp;
:: else ->
dynticks_nmi_nesting = 0;
atomic {
dynticks = dynticks + 1;
}
assert((dynticks & 1) == 0);
fi;
}
/*
* Base-level NMI runs non-atomically. Crudely emulates process-level
* dynticks-idle entry/exit.
*/
proctype base_NMI()
{
byte busy;
busy = 0;
do
:: /* Emulate base-level dynticks and not. */
if
:: 1 -> atomic {
dynticks = dynticks + 1;
}
busy = 1;
:: 1 -> skip;
fi;
/* Verify that we only sometimes have base-level dynticks. */
if
:: busy == 0 -> skip;
:: busy == 1 -> skip;
fi;
/* Model RCU's NMI entry and exit actions. */
rcu_nmi_enter();
assert((dynticks & 1) == 1);
rcu_nmi_exit();
/* Emulated re-entering base-level dynticks and not. */
if
:: !busy -> skip;
:: busy ->
atomic {
dynticks = dynticks + 1;
}
busy = 0;
fi;
/* We had better now be in dyntick-idle mode. */
assert((dynticks & 1) == 0);
od;
}
/*
* Nested NMI runs atomically to emulate interrupting base_level().
*/
proctype nested_NMI()
{
do
:: /*
* Use an atomic section to model a nested NMI. This is
* guaranteed to interleave into base_NMI() between a pair
* of base_NMI() statements, just as a nested NMI would.
*/
atomic {
/* Verify that we only sometimes are in dynticks. */
if
:: (dynticks & 1) == 0 -> skip;
:: (dynticks & 1) == 1 -> skip;
fi;
/* Model RCU's NMI entry and exit actions. */
rcu_nmi_enter();
assert((dynticks & 1) == 1);
rcu_nmi_exit();
}
od;
}
init {
run base_NMI();
run nested_NMI();
}
------------------------------------------------------------------------
The following script can be used to run this model if placed in
rcu_nmi.spin:
------------------------------------------------------------------------
if ! spin -a rcu_nmi.spin
then
echo Spin errors!!!
exit 1
fi
if ! cc -DSAFETY -o pan pan.c
then
echo Compilation errors!!!
exit 1
fi
./pan -m100000
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This removes the last few uses of CONFIG_PM_RUNTIME introduced
recently and makes that config option finally go away.
CONFIG_PM will be available directly from the menu now and
also it will be selected automatically if CONFIG_SUSPEND or
CONFIG_HIBERNATION is set.
/
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Merge tag 'pm-config-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull CONFIG_PM_RUNTIME elimination from Rafael Wysocki:
"This removes the last few uses of CONFIG_PM_RUNTIME introduced
recently and makes that config option finally go away.
CONFIG_PM will be available directly from the menu now and also it
will be selected automatically if CONFIG_SUSPEND or CONFIG_HIBERNATION
is set"
* tag 'pm-config-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: Eliminate CONFIG_PM_RUNTIME
tty: 8250_omap: Replace CONFIG_PM_RUNTIME with CONFIG_PM
sound: sst-haswell-pcm: Replace CONFIG_PM_RUNTIME with CONFIG_PM
spi: Replace CONFIG_PM_RUNTIME with CONFIG_PM
Having switched over all of the users of CONFIG_PM_RUNTIME to use
CONFIG_PM directly, turn the latter into a user-selectable option
and drop the former entirely from the tree.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Kevin Hilman <khilman@linaro.org>
Pull NOHZ update from Thomas Gleixner:
"Remove the call into the nohz idle code from the fake 'idle' thread in
the powerclamp driver along with the export of those functions which
was smuggeled in via the thermal tree. People have tried to hack
around it in the nohz core code, but it just violates all rightful
assumptions of that code about the only valid calling context (i.e.
the proper idle task).
The powerclamp trainwreck will still work, it just wont get the
benefit of long idle sleeps"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/powerclamp: Remove tick_nohz_idle abuse
Pull irq core fix from Thomas Gleixner:
"A single fix plugging a long standing race between proc/stat and
proc/interrupts access and freeing of interrupt descriptors"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
genirq: Prevent proc race against freeing of irq descriptors
Pull perf fixes and cleanups from Ingo Molnar:
"A kernel fix plus mostly tooling fixes, but also some tooling
restructuring and cleanups"
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
perf: Fix building warning on ARM 32
perf symbols: Fix use after free in filename__read_build_id
perf evlist: Use roundup_pow_of_two
tools: Adopt roundup_pow_of_two
perf tools: Make the mmap length autotuning more robust
tools: Adopt rounddown_pow_of_two and deps
tools: Adopt fls_long and deps
tools: Move bitops.h from tools/perf/util to tools/
tools: Introduce asm-generic/bitops.h
tools lib: Move asm-generic/bitops/find.h code to tools/include and tools/lib
tools: Whitespace prep patches for moving bitops.h
tools: Move code originally from asm-generic/atomic.h into tools/include/asm-generic/
tools: Move code originally from linux/log2.h to tools/include/linux/
tools: Move __ffs implementation to tools/include/asm-generic/bitops/__ffs.h
perf evlist: Do not use hard coded value for a mmap_pages default
perf trace: Let the perf_evlist__mmap autosize the number of pages to use
perf evlist: Improve the strerror_mmap method
perf evlist: Clarify sterror_mmap variable names
perf evlist: Fixup brown paper bag on "hint" for --mmap-pages cmdline arg
perf trace: Provide a better explanation when mmap fails
...
commit 4dbd27711c "tick: export nohz tick idle symbols for module
use" was merged via the thermal tree without an explicit ack from the
relevant maintainers.
The exports are abused by the intel powerclamp driver which implements
a fake idle state from a sched FIFO task. This causes all kinds of
wreckage in the NOHZ core code which rightfully assumes that
tick_nohz_idle_enter/exit() are only called from the idle task itself.
Recent changes in the NOHZ core lead to a failure of the powerclamp
driver and now people try to hack completely broken and backwards
workarounds into the NOHZ core code. This is completely unacceptable
and just papers over the real problem. There are way more subtle
issues lurking around the corner.
The real solution is to fix the powerclamp driver by rewriting it with
a sane concept, but that's beyond the scope of this.
So the only solution for now is to remove the calls into the core NOHZ
code from the powerclamp trainwreck along with the exports.
Fixes: d6d71ee4a1 "PM: Introduce Intel PowerClamp Driver"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Pan Jacob jun <jacob.jun.pan@intel.com>
Cc: LKP <lkp@01.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412181110110.17382@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
removal. This is possible by using a simple atomic_t for the counter,
rather than our fancy per-cpu counter: it turns out that no one is doing
a module increment per net packet, so the slowdown should be in the noise.
Also, script fixed for new git version.
Cheers,
Rusty.
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Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module updates from Rusty Russell:
"The exciting thing here is the getting rid of stop_machine on module
removal. This is possible by using a simple atomic_t for the counter,
rather than our fancy per-cpu counter: it turns out that no one is
doing a module increment per net packet, so the slowdown should be in
the noise"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
param: do not set store func without write perm
params: cleanup sysfs allocation
kernel:module Fix coding style errors and warnings.
module: Remove stop_machine from module unloading
module: Replace module_ref with atomic_t refcnt
lib/bug: Use RCU list ops for module_bug_list
module: Unlink module with RCU synchronizing instead of stop_machine
module: Wait for RCU synchronizing before releasing a module
- Fix a regression in leds-gpio introduced by a recent commit that
inadvertently changed the name of one of the properties used by
the driver (Fabio Estevam).
- Fix a regression in the ACPI backlight driver introduced by a
recent fix that missed one special case that had to be taken
into account (Aaron Lu).
- Drop the level of some new kernel messages from the ACPI core
introduced by a recent commit to KERN_DEBUG which they should
have used from the start and drop some other unuseful KERN_ERR
messages printed by ACPI (Rafael J Wysocki).
- Revert an incorrect commit modifying the cpupower tool
(Prarit Bhargava).
- Fix two regressions introduced by recent commits in the OPP
library and clean up some existing minor issues in that code
(Viresh Kumar).
- Continue to replace CONFIG_PM_RUNTIME with CONFIG_PM throughout
the tree (or drop it where that can be done) in order to make
it possible to eliminate CONFIG_PM_RUNTIME (Rafael J Wysocki,
Ulf Hansson, Ludovic Desroches). There will be one more
"CONFIG_PM_RUNTIME removal" batch after this one, because some
new uses of it have been introduced during the current merge
window, but that should be sufficient to finally get rid of it.
- Make the ACPI EC driver more robust against race conditions
related to GPE handler installation failures (Lv Zheng).
- Prevent the ACPI device PM core code from attempting to
disable GPEs that it has not enabled which confuses ACPICA
and makes it report errors unnecessarily (Rafael J Wysocki).
- Add a "force" command line switch to the intel_pstate driver
to make it possible to override the blacklisting of some
systems in that driver if needed (Ethan Zhao).
- Improve intel_pstate code documentation and add a MAINTAINERS
entry for it (Kristen Carlson Accardi).
- Make the ACPI fan driver create cooling device interfaces
witn names that reflect the IDs of the ACPI device objects
they are associated with, except for "generic" ACPI fans
(PNP ID "PNP0C0B"). That's necessary for user space thermal
management tools to be able to connect the fans with the
parts of the system they are supposed to be cooling properly.
From Srinivas Pandruvada.
/
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Merge tag 'pm+acpi-3.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more ACPI and power management updates from Rafael Wysocki:
"These are regression fixes (leds-gpio, ACPI backlight driver,
operating performance points library, ACPI device enumeration
messages, cpupower tool), other bug fixes (ACPI EC driver, ACPI device
PM), some cleanups in the operating performance points (OPP)
framework, continuation of CONFIG_PM_RUNTIME elimination, a couple of
minor intel_pstate driver changes, a new MAINTAINERS entry for it and
an ACPI fan driver change needed for better support of thermal
management in user space.
Specifics:
- Fix a regression in leds-gpio introduced by a recent commit that
inadvertently changed the name of one of the properties used by the
driver (Fabio Estevam).
- Fix a regression in the ACPI backlight driver introduced by a
recent fix that missed one special case that had to be taken into
account (Aaron Lu).
- Drop the level of some new kernel messages from the ACPI core
introduced by a recent commit to KERN_DEBUG which they should have
used from the start and drop some other unuseful KERN_ERR messages
printed by ACPI (Rafael J Wysocki).
- Revert an incorrect commit modifying the cpupower tool (Prarit
Bhargava).
- Fix two regressions introduced by recent commits in the OPP library
and clean up some existing minor issues in that code (Viresh
Kumar).
- Continue to replace CONFIG_PM_RUNTIME with CONFIG_PM throughout the
tree (or drop it where that can be done) in order to make it
possible to eliminate CONFIG_PM_RUNTIME (Rafael J Wysocki, Ulf
Hansson, Ludovic Desroches).
There will be one more "CONFIG_PM_RUNTIME removal" batch after this
one, because some new uses of it have been introduced during the
current merge window, but that should be sufficient to finally get
rid of it.
- Make the ACPI EC driver more robust against race conditions related
to GPE handler installation failures (Lv Zheng).
- Prevent the ACPI device PM core code from attempting to disable
GPEs that it has not enabled which confuses ACPICA and makes it
report errors unnecessarily (Rafael J Wysocki).
- Add a "force" command line switch to the intel_pstate driver to
make it possible to override the blacklisting of some systems in
that driver if needed (Ethan Zhao).
- Improve intel_pstate code documentation and add a MAINTAINERS entry
for it (Kristen Carlson Accardi).
- Make the ACPI fan driver create cooling device interfaces witn
names that reflect the IDs of the ACPI device objects they are
associated with, except for "generic" ACPI fans (PNP ID "PNP0C0B").
That's necessary for user space thermal management tools to be able
to connect the fans with the parts of the system they are supposed
to be cooling properly. From Srinivas Pandruvada"
* tag 'pm+acpi-3.19-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (32 commits)
MAINTAINERS: add entry for intel_pstate
ACPI / video: update the skip case for acpi_video_device_in_dod()
power / PM: Eliminate CONFIG_PM_RUNTIME
NFC / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
SCSI / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
ACPI / EC: Fix unexpected ec_remove_handlers() invocations
Revert "tools: cpupower: fix return checks for sysfs_get_idlestate_count()"
tracing / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
x86 / PM: Replace CONFIG_PM_RUNTIME in io_apic.c
PM: Remove the SET_PM_RUNTIME_PM_OPS() macro
mmc: atmel-mci: use SET_RUNTIME_PM_OPS() macro
PM / Kconfig: Replace PM_RUNTIME with PM in dependencies
ARM / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
sound / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
phy / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
video / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
tty / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PM
spi: Replace CONFIG_PM_RUNTIME with CONFIG_PM
ACPI / PM: Do not disable wakeup GPEs that have not been enabled
ACPI / utils: Drop error messages from acpi_evaluate_reference()
...
When a module_param is defined without DAC write permissions, it can
still be changed at runtime and updated. Drivers using a 0444 permission
may be surprised that these values can still be changed.
For drivers that want to allow updates, any S_IW* flag will set the
"store" function as before. Drivers without S_IW* flags will have the
"store" function unset, unforcing a read-only value. Drivers that wish
neither "store" nor "get" can continue to use "0" for perms to stay out
of sysfs entirely.
Old behavior:
# cd /sys/module/snd/parameters
# ls -l
total 0
-r--r--r-- 1 root root 4096 Dec 11 13:55 cards_limit
-r--r--r-- 1 root root 4096 Dec 11 13:55 major
-r--r--r-- 1 root root 4096 Dec 11 13:55 slots
# cat major
116
# echo -1 > major
-bash: major: Permission denied
# chmod u+w major
# echo -1 > major
# cat major
-1
New behavior:
...
# chmod u+w major
# echo -1 > major
-bash: echo: write error: Input/output error
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Pull user namespace related fixes from Eric Biederman:
"As these are bug fixes almost all of thes changes are marked for
backporting to stable.
The first change (implicitly adding MNT_NODEV on remount) addresses a
regression that was created when security issues with unprivileged
remount were closed. I go on to update the remount test to make it
easy to detect if this issue reoccurs.
Then there are a handful of mount and umount related fixes.
Then half of the changes deal with the a recently discovered design
bug in the permission checks of gid_map. Unix since the beginning has
allowed setting group permissions on files to less than the user and
other permissions (aka ---rwx---rwx). As the unix permission checks
stop as soon as a group matches, and setgroups allows setting groups
that can not later be dropped, results in a situtation where it is
possible to legitimately use a group to assign fewer privileges to a
process. Which means dropping a group can increase a processes
privileges.
The fix I have adopted is that gid_map is now no longer writable
without privilege unless the new file /proc/self/setgroups has been
set to permanently disable setgroups.
The bulk of user namespace using applications even the applications
using applications using user namespaces without privilege remain
unaffected by this change. Unfortunately this ix breaks a couple user
space applications, that were relying on the problematic behavior (one
of which was tools/selftests/mount/unprivileged-remount-test.c).
To hopefully prevent needing a regression fix on top of my security
fix I rounded folks who work with the container implementations mostly
like to be affected and encouraged them to test the changes.
> So far nothing broke on my libvirt-lxc test bed. :-)
> Tested with openSUSE 13.2 and libvirt 1.2.9.
> Tested-by: Richard Weinberger <richard@nod.at>
> Tested on Fedora20 with libvirt 1.2.11, works fine.
> Tested-by: Chen Hanxiao <chenhanxiao@cn.fujitsu.com>
> Ok, thanks - yes, unprivileged lxc is working fine with your kernels.
> Just to be sure I was testing the right thing I also tested using
> my unprivileged nsexec testcases, and they failed on setgroup/setgid
> as now expected, and succeeded there without your patches.
> Tested-by: Serge Hallyn <serge.hallyn@ubuntu.com>
> I tested this with Sandstorm. It breaks as is and it works if I add
> the setgroups thing.
> Tested-by: Andy Lutomirski <luto@amacapital.net> # breaks things as designed :("
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
userns: Unbreak the unprivileged remount tests
userns; Correct the comment in map_write
userns: Allow setting gid_maps without privilege when setgroups is disabled
userns: Add a knob to disable setgroups on a per user namespace basis
userns: Rename id_map_mutex to userns_state_mutex
userns: Only allow the creator of the userns unprivileged mappings
userns: Check euid no fsuid when establishing an unprivileged uid mapping
userns: Don't allow unprivileged creation of gid mappings
userns: Don't allow setgroups until a gid mapping has been setablished
userns: Document what the invariant required for safe unprivileged mappings.
groups: Consolidate the setgroups permission checks
mnt: Clear mnt_expire during pivot_root
mnt: Carefully set CL_UNPRIVILEGED in clone_mnt
mnt: Move the clear of MNT_LOCKED from copy_tree to it's callers.
umount: Do not allow unmounting rootfs.
umount: Disallow unprivileged mount force
mnt: Update unprivileged remount test
mnt: Implicitly add MNT_NODEV on remount when it was implicitly added by mount
Pull vfs pile #2 from Al Viro:
"Next pile (and there'll be one or two more).
The large piece in this one is getting rid of /proc/*/ns/* weirdness;
among other things, it allows to (finally) make nameidata completely
opaque outside of fs/namei.c, making for easier further cleanups in
there"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
coda_venus_readdir(): use file_inode()
fs/namei.c: fold link_path_walk() call into path_init()
path_init(): don't bother with LOOKUP_PARENT in argument
fs/namei.c: new helper (path_cleanup())
path_init(): store the "base" pointer to file in nameidata itself
make default ->i_fop have ->open() fail with ENXIO
make nameidata completely opaque outside of fs/namei.c
kill proc_ns completely
take the targets of /proc/*/ns/* symlinks to separate fs
bury struct proc_ns in fs/proc
copy address of proc_ns_ops into ns_common
new helpers: ns_alloc_inum/ns_free_inum
make proc_ns_operations work with struct ns_common * instead of void *
switch the rest of proc_ns_operations to working with &...->ns
netns: switch ->get()/->put()/->install()/->inum() to working with &net->ns
make mntns ->get()/->put()/->install()/->inum() work with &mnt_ns->ns
common object embedded into various struct ....ns
as I thought it might be. I'm pushing this in now.
This will allow Thomas to debug his irq work for 3.20.
This adds two new features:
1) Allow traceopoints to be enabled right after mm_init(). By passing
in the trace_event= kernel command line parameter, tracepoints can be
enabled at boot up. For debugging things like the initialization of
interrupts, it is needed to have tracepoints enabled very early. People
have asked about this before and this has been on my todo list. As it
can be helpful for Thomas to debug his upcoming 3.20 IRQ work, I'm
pushing this now. This way he can add tracepoints into the IRQ set up
and have users enable them when things go wrong.
2) Have the tracepoints printed via printk() (the console) when they
are triggered. If the irq code locks up or reboots the box, having the
tracepoint output go into the kernel ring buffer is useless for
debugging. But being able to add the tp_printk kernel command line
option along with the trace_event= option will have these tracepoints
printed as they occur, and that can be really useful for debugging
early lock up or reboot problems.
This code is not that intrusive and it passed all my tests. Thomas tried
them out too and it works for his needs.
Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org
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Merge tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"As the merge window is still open, and this code was not as complex as
I thought it might be. I'm pushing this in now.
This will allow Thomas to debug his irq work for 3.20.
This adds two new features:
1) Allow traceopoints to be enabled right after mm_init().
By passing in the trace_event= kernel command line parameter,
tracepoints can be enabled at boot up. For debugging things like
the initialization of interrupts, it is needed to have tracepoints
enabled very early. People have asked about this before and this
has been on my todo list. As it can be helpful for Thomas to debug
his upcoming 3.20 IRQ work, I'm pushing this now. This way he can
add tracepoints into the IRQ set up and have users enable them when
things go wrong.
2) Have the tracepoints printed via printk() (the console) when they
are triggered.
If the irq code locks up or reboots the box, having the tracepoint
output go into the kernel ring buffer is useless for debugging.
But being able to add the tp_printk kernel command line option
along with the trace_event= option will have these tracepoints
printed as they occur, and that can be really useful for debugging
early lock up or reboot problems.
This code is not that intrusive and it passed all my tests. Thomas
tried them out too and it works for his needs.
Link: http://lkml.kernel.org/r/20141214201609.126831471@goodmis.org"
* tag 'trace-3.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Add tp_printk cmdline to have tracepoints go to printk()
tracing: Move enabling tracepoints to just after rcu_init()
Pull drm updates from Dave Airlie:
"Highlights:
- AMD KFD driver merge
This is the AMD HSA interface for exposing a lowlevel interface for
GPGPU use. They have an open source userspace built on top of this
interface, and the code looks as good as it was going to get out of
tree.
- Initial atomic modesetting work
The need for an atomic modesetting interface to allow userspace to
try and send a complete set of modesetting state to the driver has
arisen, and been suffering from neglect this past year. No more,
the start of the common code and changes for msm driver to use it
are in this tree. Ongoing work to get the userspace ioctl finished
and the code clean will probably wait until next kernel.
- DisplayID 1.3 and tiled monitor exposed to userspace.
Tiled monitor property is now exposed for userspace to make use of.
- Rockchip drm driver merged.
- imx gpu driver moved out of staging
Other stuff:
- core:
panel - MIPI DSI + new panels.
expose suggested x/y properties for virtual GPUs
- i915:
Initial Skylake (SKL) support
gen3/4 reset work
start of dri1/ums removal
infoframe tracking
fixes for lots of things.
- nouveau:
tegra k1 voltage support
GM204 modesetting support
GT21x memory reclocking work
- radeon:
CI dpm fixes
GPUVM improvements
Initial DPM fan control
- rcar-du:
HDMI support added
removed some support for old boards
slave encoder driver for Analog Devices adv7511
- exynos:
Exynos4415 SoC support
- msm:
a4xx gpu support
atomic helper conversion
- tegra:
iommu support
universal plane support
ganged-mode DSI support
- sti:
HDMI i2c improvements
- vmwgfx:
some late fixes.
- qxl:
use suggested x/y properties"
* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (969 commits)
drm: sti: fix module compilation issue
drm/i915: save/restore GMBUS freq across suspend/resume on gen4
drm: sti: correctly cleanup CRTC and planes
drm: sti: add HQVDP plane
drm: sti: add cursor plane
drm: sti: enable auxiliary CRTC
drm: sti: fix delay in VTG programming
drm: sti: prepare sti_tvout to support auxiliary crtc
drm: sti: use drm_crtc_vblank_{on/off} instead of drm_vblank_{on/off}
drm: sti: fix hdmi avi infoframe
drm: sti: remove event lock while disabling vblank
drm: sti: simplify gdp code
drm: sti: clear all mixer control
drm: sti: remove gpio for HDMI hot plug detection
drm: sti: allow to change hdmi ddc i2c adapter
drm/doc: Document drm_add_modes_noedid() usage
drm/i915: Remove '& 0xffff' from the mask given to WA_REG()
drm/i915: Invert the mask and val arguments in wa_add() and WA_REG()
drm: Zero out DRM object memory upon cleanup
drm/i915/bdw: Fix the write setting up the WIZ hashing mode
...
Add the kernel command line tp_printk option that will have tracepoints
that are active sent to printk() as well as to the trace buffer.
Passing "tp_printk" will activate this. To turn it off, the sysctl
/proc/sys/kernel/tracepoint_printk can have '0' echoed into it. Note,
this only works if the cmdline option is used. Echoing 1 into the sysctl
file without the cmdline option will have no affect.
Note, this is a dangerous option. Having high frequency tracepoints send
their data to printk() can possibly cause a live lock. This is another
reason why this is only active if the command line option is used.
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Enabling tracepoints at boot up can be very useful. The tracepoint
can be initialized right after RCU has been. There's no need to
wait for the early_initcall() to be called. That's too late for some
things that can use tracepoints for debugging. Move the logic to
enable tracepoints out of the initcalls and into init/main.c to
right after rcu_init().
This also allows trace_printk() to be used early too.
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1412121539300.16494@nanos
Link: http://lkml.kernel.org/r/20141214164104.307127356@goodmis.org
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Here's the big tty/serial driver update for 3.19-rc1.
There are a number of TTY core changes/fixes in here from Peter Hurley
that have all been teted in linux-next for a long time now. There are
also the normal serial driver updates as well, full details in the
changelog below.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial driver updates from Greg KH:
"Here's the big tty/serial driver update for 3.19-rc1.
There are a number of TTY core changes/fixes in here from Peter Hurley
that have all been teted in linux-next for a long time now. There are
also the normal serial driver updates as well, full details in the
changelog below"
* tag 'tty-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (219 commits)
serial: pxa: hold port.lock when reporting modem line changes
tty-hvsi_lib: Deletion of an unnecessary check before the function call "tty_kref_put"
tty: Deletion of unnecessary checks before two function calls
n_tty: Fix read_buf race condition, increment read_head after pushing data
serial: of-serial: add PM suspend/resume support
Revert "serial: of-serial: add PM suspend/resume support"
Revert "serial: of-serial: fix up PM ops on no_console_suspend and port type"
serial: 8250: don't attempt a trylock if in sysrq
serial: core: Add big-endian iotype
serial: samsung: use port->fifosize instead of hardcoded values
serial: samsung: prefer to use fifosize from driver data
serial: samsung: fix style problems
serial: samsung: wait for transfer completion before clock disable
serial: icom: fix error return code
serial: tegra: clean up tty-flag assignments
serial: Fix io address assign flow with Fintek PCI-to-UART Product
serial: mxs-auart: fix tx_empty against shift register
serial: mxs-auart: fix gpio change detection on interrupt
serial: mxs-auart: Fix mxs_auart_set_ldisc()
serial: 8250_dw: Use 64-bit access for OCTEON.
...
Pull block driver core update from Jens Axboe:
"This is the pull request for the core block IO changes for 3.19. Not
a huge round this time, mostly lots of little good fixes:
- Fix a bug in sysfs blktrace interface causing a NULL pointer
dereference, when enabled/disabled through that API. From Arianna
Avanzini.
- Various updates/fixes/improvements for blk-mq:
- A set of updates from Bart, mostly fixing buts in the tag
handling.
- Cleanup/code consolidation from Christoph.
- Extend queue_rq API to be able to handle batching issues of IO
requests. NVMe will utilize this shortly. From me.
- A few tag and request handling updates from me.
- Cleanup of the preempt handling for running queues from Paolo.
- Prevent running of unmapped hardware queues from Ming Lei.
- Move the kdump memory limiting check to be in the correct
location, from Shaohua.
- Initialize all software queues at init time from Takashi. This
prevents a kobject warning when CPUs are brought online that
weren't online when a queue was registered.
- Single writeback fix for I_DIRTY clearing from Tejun. Queued with
the core IO changes, since it's just a single fix.
- Version X of the __bio_add_page() segment addition retry from
Maurizio. Hope the Xth time is the charm.
- Documentation fixup for IO scheduler merging from Jan.
- Introduce (and use) generic IO stat accounting helpers for non-rq
drivers, from Gu Zheng.
- Kill off artificial limiting of max sectors in a request from
Christoph"
* 'for-3.19/core' of git://git.kernel.dk/linux-block: (26 commits)
bio: modify __bio_add_page() to accept pages that don't start a new segment
blk-mq: Fix uninitialized kobject at CPU hotplugging
blktrace: don't let the sysfs interface remove trace from running list
blk-mq: Use all available hardware queues
blk-mq: Micro-optimize bt_get()
blk-mq: Fix a race between bt_clear_tag() and bt_get()
blk-mq: Avoid that __bt_get_word() wraps multiple times
blk-mq: Fix a use-after-free
blk-mq: prevent unmapped hw queue from being scheduled
blk-mq: re-check for available tags after running the hardware queue
blk-mq: fix hang in bt_get()
blk-mq: move the kdump check to blk_mq_alloc_tag_set
blk-mq: cleanup tag free handling
blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map
blk: introduce generic io stat accounting help function
blk-mq: handle the single queue case in blk_mq_hctx_next_cpu
genhd: check for int overflow in disk_expand_part_tbl()
blk-mq: add blk_mq_free_hctx_request()
blk-mq: export blk_mq_free_request()
blk-mq: use get_cpu/put_cpu instead of preempt_disable/preempt_enable
...
clean ups from that branch.
This code solves the issue of performing stack dumps from NMI context.
The issue is that printk() is not safe from NMI context as if the NMI
were to trigger when a printk() was being performed, the NMI could
deadlock from the printk() internal locks. This has been seen in practice.
With lots of review from Petr Mladek, this code went through several
iterations, and we feel that it is now at a point of quality to be
accepted into mainline.
Here's what is contained in this patch set:
o Creates a "seq_buf" generic buffer utility that allows a descriptor
to be passed around where functions can write their own "printk()"
formatted strings into it. The generic version was pulled out of
the trace_seq() code that was made specifically for tracing.
o The seq_buf code was change to model the seq_file code. I have
a patch (not included for 3.19) that converts the seq_file.c code
over to use seq_buf.c like the trace_seq.c code does. This was done
to make sure that seq_buf.c is compatible with seq_file.c. I may
try to get that patch in for 3.20.
o The seq_buf.c file was moved to lib/ to remove it from being dependent
on CONFIG_TRACING.
o The printk() was updated to allow for a per_cpu "override" of
the internal calls. That is, instead of writing to the console, a call
to printk() may do something else. This made it easier to allow the
NMI to change what printk() does in order to call dump_stack() without
needing to update that code as well.
o Finally, the dump_stack from all CPUs via NMI code was converted to
use the seq_buf code. The caller to trigger the NMI code would wait
till all the NMIs finished, and then it would print the seq_buf
data to the console safely from a non NMI context.
[ Updated to remove unnecessary preempt_disable in printk() ]
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Merge tag 'trace-seq-buf-3.19-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixlet from Steven Rostedt:
"Remove unnecessary preempt_disable in printk()"
* tag 'trace-seq-buf-3.19-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
printk: Do not disable preemption for accessing printk_func
Pull audit updates from Paul Moore:
"Two small patches from the audit next branch; only one of which has
any real significant code changes, the other is simply a MAINTAINERS
update for audit.
The single code patch is pretty small and rather straightforward, it
changes the audit "version" number reported to userspace from an
integer to a bitmap which is used to indicate the functionality of the
running kernel. This really doesn't have much impact on the kernel,
but it will make life easier for the audit userspace folks.
Thankfully we were still on a version number which allowed us to do
this without breaking userspace"
* 'upstream' of git://git.infradead.org/users/pcmoore/audit:
audit: convert status version to a feature bitmap
audit: add Paul Moore to the MAINTAINERS entry
There's a lot of common code in inode and mount marks handling. Factor it
out to a common helper function.
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Following the suggestions from Andrew Morton and Stephen Rothwell,
Dont expand the ARCH list in kernel/gcov/Kconfig. Instead,
define a ARCH_HAS_GCOV_PROFILE_ALL bool which architectures
can enable.
set ARCH_HAS_GCOV_PROFILE_ALL on Architectures where it was
previously allowed + ARM64 which I tested.
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset adds execveat(2) for x86, and is derived from Meredydd
Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528).
The primary aim of adding an execveat syscall is to allow an
implementation of fexecve(3) that does not rely on the /proc filesystem,
at least for executables (rather than scripts). The current glibc version
of fexecve(3) is implemented via /proc, which causes problems in sandboxed
or otherwise restricted environments.
Given the desire for a /proc-free fexecve() implementation, HPA suggested
(https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be
an appropriate generalization.
Also, having a new syscall means that it can take a flags argument without
back-compatibility concerns. The current implementation just defines the
AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be
added in future -- for example, flags for new namespaces (as suggested at
https://lkml.org/lkml/2006/7/11/474).
Related history:
- https://lkml.org/lkml/2006/12/27/123 is an example of someone
realizing that fexecve() is likely to fail in a chroot environment.
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered
documenting the /proc requirement of fexecve(3) in its manpage, to
"prevent other people from wasting their time".
- https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a
problem where a process that did setuid() could not fexecve()
because it no longer had access to /proc/self/fd; this has since
been fixed.
This patch (of 4):
Add a new execveat(2) system call. execveat() is to execve() as openat()
is to open(): it takes a file descriptor that refers to a directory, and
resolves the filename relative to that.
In addition, if the filename is empty and AT_EMPTY_PATH is specified,
execveat() executes the file to which the file descriptor refers. This
replicates the functionality of fexecve(), which is a system call in other
UNIXen, but in Linux glibc it depends on opening "/proc/self/fd/<fd>" (and
so relies on /proc being mounted).
The filename fed to the executed program as argv[0] (or the name of the
script fed to a script interpreter) will be of the form "/dev/fd/<fd>"
(for an empty filename) or "/dev/fd/<fd>/<filename>", effectively
reflecting how the executable was found. This does however mean that
execution of a script in a /proc-less environment won't work; also, script
execution via an O_CLOEXEC file descriptor fails (as the file will not be
accessible after exec).
Based on patches by Meredydd Luff.
Signed-off-by: David Drysdale <drysdale@google.com>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: Shuah Khan <shuah.kh@samsung.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rich Felker <dalias@aerifal.cx>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Current stacktrace only have the function for console output. page_owner
that will be introduced in following patch needs to print the output of
stacktrace into the buffer for our own output format so so new function,
snprint_stack_trace(), is needed.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Jungsoo Son <jungsoo.son@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Both register and unregister call build_map_info() in order to create the
list of mappings before installing or removing breakpoints for every mm
which maps file backed memory. As such, there is no reason to hold the
i_mmap_rwsem exclusively, so share it and allow concurrent readers to
build the mapping data.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The i_mmap_mutex is a close cousin of the anon vma lock, both protecting
similar data, one for file backed pages and the other for anon memory. To
this end, this lock can also be a rwsem. In addition, there are some
important opportunities to share the lock when there are no tree
modifications.
This conversion is straightforward. For now, all users take the write
lock.
[sfr@canb.auug.org.au: update fremap.c]
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the rework of the sparse interrupt code to actually free the
unused interrupt descriptors there exists a race between the /proc
interfaces to the irq subsystem and the code which frees the interrupt
descriptor.
CPU0 CPU1
show_interrupts()
desc = irq_to_desc(X);
free_desc(desc)
remove_from_radix_tree();
kfree(desc);
raw_spinlock_irq(&desc->lock);
/proc/interrupts is the only interface which can actively corrupt
kernel memory via the lock access. /proc/stat can only read from freed
memory. Extremly hard to trigger, but possible.
The interfaces in /proc/irq/N/ are not affected by this because the
removal of the proc file is serialized in procfs against concurrent
readers/writers. The removal happens before the descriptor is freed.
For architectures which have CONFIG_SPARSE_IRQ=n this is a non issue
as the descriptor is never freed. It's merely cleared out with the irq
descriptor lock held. So any concurrent proc access will either see
the old correct value or the cleared out ones.
Protect the lookup and access to the irq descriptor in
show_interrupts() with the sparse_irq_lock.
Provide kstat_irqs_usr() which is protecting the lookup and access
with sparse_irq_lock and switch /proc/stat to use it.
Document the existing kstat_irqs interfaces so it's clear that the
caller needs to take care about protection. The users of these
interfaces are either not affected due to SPARSE_IRQ=n or already
protected against removal.
Fixes: 1f5a5b87f7 "genirq: Implement a sane sparse_irq allocator"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
After commit b2b49ccbdd (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is
selected) PM_RUNTIME is always set if PM is set, so files that are
build conditionally if CONFIG_PM_RUNTIME is set may now be build
if CONFIG_PM is set.
Replace CONFIG_PM_RUNTIME with CONFIG_PM in kernel/trace/Makefile
for this reason.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org.
Pull cgroup update from Tejun Heo:
"cpuset got simplified a bit. cgroup core got a fix on unified
hierarchy and grew some effective css related interfaces which will be
used for blkio support for writeback IO traffic which is currently
being worked on"
* 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: implement cgroup_get_e_css()
cgroup: add cgroup_subsys->css_e_css_changed()
cgroup: add cgroup_subsys->css_released()
cgroup: fix the async css offline wait logic in cgroup_subtree_control_write()
cgroup: restructure child_subsys_mask handling in cgroup_subtree_control_write()
cgroup: separate out cgroup_calc_child_subsys_mask() from cgroup_refresh_child_subsys_mask()
cpuset: lock vs unlock typo
cpuset: simplify cpuset_node_allowed API
cpuset: convert callback_mutex to a spinlock
Pull workqueue update from Tejun Heo:
"Work items which may be involved in memory reclaim path may be
executed by the rescuer under memory pressure. When a rescuer gets
activated, it processes whatever are on the pending list and then goes
back to sleep until the manager kicks it again which involves 100ms
delay.
This is problematic for self-requeueing work items or the ones running
on ordered workqueues as there always is only one work item on the
pending list when the rescuer kicks in. The execution of that work
item produces more to execute but the rescuer won't see them until
after the said 100ms has passed, so such workqueues would only execute
one work item every 100ms under prolonged memory pressure, which BTW
may be being prolonged due to the slow execution.
Neil wrote up a patch which fixes this issue by keeping the rescuer
working as long as the target workqueue is busy but doesn't have
enough workers"
* 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: allow rescuer thread to do more work.
workqueue: invert the order between pool->lock and wq_mayday_lock
workqueue: cosmetic update in rescuer_thread()
Pull percpu updates from Tejun Heo:
"Nothing interesting. A patch to convert the remaining __get_cpu_var()
users, another to fix non-critical off-by-one in an assertion and a
cosmetic conversion to lockless_dereference() in percpu-ref.
The back-merge from mainline is to receive lockless_dereference()"
* 'for-3.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: Replace smp_read_barrier_depends() with lockless_dereference()
percpu: Convert remaining __get_cpu_var uses in 3.18-rcX
percpu: off by one in BUG_ON()
Here's a batch of i915 fixes for 3.19.
* tag 'drm-intel-next-fixes-2014-12-11' of git://anongit.freedesktop.org/drm-intel:
drm/i915: save/restore GMBUS freq across suspend/resume on gen4
drm/i915: Remove '& 0xffff' from the mask given to WA_REG()
drm/i915: Invert the mask and val arguments in wa_add() and WA_REG()
drm/i915/bdw: Fix the write setting up the WIZ hashing mode
drm/i915: Don't complain about stolen conflicts on gen3
drm/i915: resume MST after reading back hw state
drm/i915: Handle inaccurate time conversion issues
drm/i915: compute wait_ioctl timeout correctly
drm/i915: don't always do full mode sets when infoframes are enabled
Pull s390 updates from Martin Schwidefsky:
"The most notable change for this pull request is the ftrace rework
from Heiko. It brings a small performance improvement and the ground
work to support a new gcc option to replace the mcount blocks with a
single nop.
Two new s390 specific system calls are added to emulate user space
mmio for PCI, an artifact of the how PCI memory is accessed.
Two patches for the memory management with changes to common code.
For KVM mm_forbids_zeropage is added which disables the empty zero
page for an mm that is used by a KVM process. And an optimization,
pmdp_get_and_clear_full is added analog to ptep_get_and_clear_full.
Some micro optimization for the cmpxchg and the spinlock code.
And as usual bug fixes and cleanups"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (46 commits)
s390/cputime: fix 31-bit compile
s390/scm_block: make the number of reqs per HW req configurable
s390/scm_block: handle multiple requests in one HW request
s390/scm_block: allocate aidaw pages only when necessary
s390/scm_block: use mempool to manage aidaw requests
s390/eadm: change timeout value
s390/mm: fix memory leak of ptlock in pmd_free_tlb
s390: use local symbol names in entry[64].S
s390/ptrace: always include vector registers in core files
s390/simd: clear vector register pointer on fork/clone
s390: translate cputime magic constants to macros
s390/idle: convert open coded idle time seqcount
s390/idle: add missing irq off lockdep annotation
s390/debug: avoid function call for debug_sprintf_*
s390/kprobes: fix instruction copy for out of line execution
s390: remove diag 44 calls from cpu_relax()
s390/dasd: retry partition detection
s390/dasd: fix list corruption for sleep_on requests
s390/dasd: fix infinite term I/O loop
s390/dasd: remove unused code
...
It is important that all maps are less than PAGE_SIZE
or else setting the last byte of the buffer to '0'
could write off the end of the allocated storage.
Correct the misleading comment.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Now that setgroups can be disabled and not reenabled, setting gid_map
without privielge can now be enabled when setgroups is disabled.
This restores most of the functionality that was lost when unprivileged
setting of gid_map was removed. Applications that use this functionality
will need to check to see if they use setgroups or init_groups, and if they
don't they can be fixed by simply disabling setgroups before writing to
gid_map.
Cc: stable@vger.kernel.org
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
- Expose the knob to user space through a proc file /proc/<pid>/setgroups
A value of "deny" means the setgroups system call is disabled in the
current processes user namespace and can not be enabled in the
future in this user namespace.
A value of "allow" means the segtoups system call is enabled.
- Descendant user namespaces inherit the value of setgroups from
their parents.
- A proc file is used (instead of a sysctl) as sysctls currently do
not allow checking the permissions at open time.
- Writing to the proc file is restricted to before the gid_map
for the user namespace is set.
This ensures that disabling setgroups at a user namespace
level will never remove the ability to call setgroups
from a process that already has that ability.
A process may opt in to the setgroups disable for itself by
creating, entering and configuring a user namespace or by calling
setns on an existing user namespace with setgroups disabled.
Processes without privileges already can not call setgroups so this
is a noop. Prodcess with privilege become processes without
privilege when entering a user namespace and as with any other path
to dropping privilege they would not have the ability to call
setgroups. So this remains within the bounds of what is possible
without a knob to disable setgroups permanently in a user namespace.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Pull networking updates from David Miller:
1) New offloading infrastructure and example 'rocker' driver for
offloading of switching and routing to hardware.
This work was done by a large group of dedicated individuals, not
limited to: Scott Feldman, Jiri Pirko, Thomas Graf, John Fastabend,
Jamal Hadi Salim, Andy Gospodarek, Florian Fainelli, Roopa Prabhu
2) Start making the networking operate on IOV iterators instead of
modifying iov objects in-situ during transfers. Thanks to Al Viro
and Herbert Xu.
3) A set of new netlink interfaces for the TIPC stack, from Richard
Alpe.
4) Remove unnecessary looping during ipv6 routing lookups, from Martin
KaFai Lau.
5) Add PAUSE frame generation support to gianfar driver, from Matei
Pavaluca.
6) Allow for larger reordering levels in TCP, which are easily
achievable in the real world right now, from Eric Dumazet.
7) Add a variable of napi_schedule that doesn't need to disable cpu
interrupts, from Eric Dumazet.
8) Use a doubly linked list to optimize neigh_parms_release(), from
Nicolas Dichtel.
9) Various enhancements to the kernel BPF verifier, and allow eBPF
programs to actually be attached to sockets. From Alexei
Starovoitov.
10) Support TSO/LSO in sunvnet driver, from David L Stevens.
11) Allow controlling ECN usage via routing metrics, from Florian
Westphal.
12) Remote checksum offload, from Tom Herbert.
13) Add split-header receive, BQL, and xmit_more support to amd-xgbe
driver, from Thomas Lendacky.
14) Add MPLS support to openvswitch, from Simon Horman.
15) Support wildcard tunnel endpoints in ipv6 tunnels, from Steffen
Klassert.
16) Do gro flushes on a per-device basis using a timer, from Eric
Dumazet. This tries to resolve the conflicting goals between the
desired handling of bulk vs. RPC-like traffic.
17) Allow userspace to ask for the CPU upon what a packet was
received/steered, via SO_INCOMING_CPU. From Eric Dumazet.
18) Limit GSO packets to half the current congestion window, from Eric
Dumazet.
19) Add a generic helper so that all drivers set their RSS keys in a
consistent way, from Eric Dumazet.
20) Add xmit_more support to enic driver, from Govindarajulu
Varadarajan.
21) Add VLAN packet scheduler action, from Jiri Pirko.
22) Support configurable RSS hash functions via ethtool, from Eyal
Perry.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1820 commits)
Fix race condition between vxlan_sock_add and vxlan_sock_release
net/macb: fix compilation warning for print_hex_dump() called with skb->mac_header
net/mlx4: Add support for A0 steering
net/mlx4: Refactor QUERY_PORT
net/mlx4_core: Add explicit error message when rule doesn't meet configuration
net/mlx4: Add A0 hybrid steering
net/mlx4: Add mlx4_bitmap zone allocator
net/mlx4: Add a check if there are too many reserved QPs
net/mlx4: Change QP allocation scheme
net/mlx4_core: Use tasklet for user-space CQ completion events
net/mlx4_core: Mask out host side virtualization features for guests
net/mlx4_en: Set csum level for encapsulated packets
be2net: Export tunnel offloads only when a VxLAN tunnel is created
gianfar: Fix dma check map error when DMA_API_DEBUG is enabled
cxgb4/csiostor: Don't use MASTER_MUST for fw_hello call
net: fec: only enable mdio interrupt before phy device link up
net: fec: clear all interrupt events to support i.MX6SX
net: fec: reset fep link status in suspend function
net: sock: fix access via invalid file descriptor
net: introduce helper macro for_each_cmsghdr
...
As printk_func will either be the default function, or a per_cpu function
for the current CPU, there's no reason to disable preemption to access
it from printk. That's because if the printk_func is not the default
then the caller had better disabled preemption as they were the one to
change it.
Link: http://lkml.kernel.org/r/CA+55aFz5-_LKW4JHEBoWinN9_ouNcGRWAF2FUA35u46FRN-Kxw@mail.gmail.com
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
We allow PMU driver to change the cpu on which the event
should be installed to. This happened in patch:
e2d37cd213 ("perf: Allow the PMU driver to choose the CPU on which to install events")
This patch also forces all the group members to follow
the currently opened events cpu if the group happened
to be moved.
This and the change of event->cpu in perf_install_in_context()
function introduced in:
0cda4c0231 ("perf: Introduce perf_pmu_migrate_context()")
forces group members to change their event->cpu,
if the currently-opened-event's PMU changed the cpu
and there is a group move.
Above behaviour causes problem for breakpoint events,
which uses event->cpu to touch cpu specific data for
breakpoints accounting. By changing event->cpu, some
breakpoints slots were wrongly accounted for given
cpu.
Vinces's perf fuzzer hit this issue and caused following
WARN on my setup:
WARNING: CPU: 0 PID: 20214 at arch/x86/kernel/hw_breakpoint.c:119 arch_install_hw_breakpoint+0x142/0x150()
Can't find any breakpoint slot
[...]
This patch changes the group moving code to keep the event's
original cpu.
Reported-by: Vince Weaver <vince@deater.net>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vince@deater.net>
Cc: Yan, Zheng <zheng.z.yan@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1418243031-20367-3-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Calvin Owens
Lai Jiangshan
Paul E. McKenney
David Hildenbrand
Alexander Gordeev
Linus Torvalds
Rafael J. Wysocki
Thomas Gleixner
Kees Cook
Steven Rostedt (Red Hat)
Jan Kara
Riku Voipio
Masanari Iida
David Drysdale
Joonsoo Kim
Davidlohr Bueso
Ingo Molnar
Dave Airlie
Eric W. Biederman
Jiri Olsa