Skip to content

cloud-kernel
cloud-kernel

openanolis / cloud-kernel
1 年多 前同步成功

通知 161
Star 36
Fork 7
cloud-kernel
cloud-kernel
切换分支/标签
  1. 01 4月, 2015 9 次提交
  3. 27 3月, 2015 13 次提交
  5. 26 3月, 2015 1 次提交
    • M
      mm: numa: slow PTE scan rate if migration failures occur · 074c2381
      由 Mel Gorman 提交于 
      Dave Chinner reported the following on https://lkml.org/lkml/2015/3/1/226

  Across the board the 4.0-rc1 numbers are much slower, and the degradation
  is far worse when using the large memory footprint configs. Perf points
  straight at the cause - this is from 4.0-rc1 on the "-o bhash=101073" config:

   -   56.07%    56.07%  [kernel]            [k] default_send_IPI_mask_sequence_phys
      - default_send_IPI_mask_sequence_phys
         - 99.99% physflat_send_IPI_mask
            - 99.37% native_send_call_func_ipi
                 smp_call_function_many
               - native_flush_tlb_others
                  - 99.85% flush_tlb_page
                       ptep_clear_flush
                       try_to_unmap_one
                       rmap_walk
                       try_to_unmap
                       migrate_pages
                       migrate_misplaced_page
                     - handle_mm_fault
                        - 99.73% __do_page_fault
                             trace_do_page_fault
                             do_async_page_fault
                           + async_page_fault
              0.63% native_send_call_func_single_ipi
                 generic_exec_single
                 smp_call_function_single

This is showing excessive migration activity even though excessive
migrations are meant to get throttled.  Normally, the scan rate is tuned
on a per-task basis depending on the locality of faults.  However, if
migrations fail for any reason then the PTE scanner may scan faster if
the faults continue to be remote.  This means there is higher system CPU
overhead and fault trapping at exactly the time we know that migrations
cannot happen.  This patch tracks when migration failures occur and
slows the PTE scanner.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Reported-by: NDave Chinner <david@fromorbit.com>
Tested-by: NDave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      074c2381
  7. 23 3月, 2015 4 次提交
    • P
      timers/tick/broadcast-hrtimer: Fix suspicious RCU usage in idle loop · a127d2bc
      由 Preeti U Murthy 提交于 
      The hrtimer mode of broadcast queues hrtimers in the idle entry
path so as to wakeup cpus in deep idle states. The associated
call graph is :

	cpuidle_idle_call()
	|____ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, ....))
	     |_____tick_broadcast_set_event()
		   |____clockevents_program_event()
			|____bc_set_next()

The hrtimer_{start/cancel} functions call into tracing which uses RCU.
But it is not legal to call into RCU in cpuidle because it is one of the
quiescent states. Hence protect this region with RCU_NONIDLE which informs
RCU that the cpu is momentarily non-idle.

As an aside it is helpful to point out that the clock event device that is
programmed here is not a per-cpu clock device; it is a
pseudo clock device, used by the broadcast framework alone.
The per-cpu clock device programming never goes through bc_set_next().
Signed-off-by: NPreeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: linuxppc-dev@ozlabs.org
Cc: mpe@ellerman.id.au
Cc: tglx@linutronix.de
Link: http://lkml.kernel.org/r/20150318104705.17763.56668.stgit@preeti.in.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      a127d2bc
    • P
      lockdep: Fix the module unload key range freeing logic · 35a9393c
      由 Peter Zijlstra 提交于 
      Module unload calls lockdep_free_key_range(), which removes entries
from the data structures. Most of the lockdep code OTOH assumes the
data structures are append only; in specific see the comments in
add_lock_to_list() and look_up_lock_class().

Clearly this has only worked by accident; make it work proper. The
actual scenario to make it go boom would involve the memory freed by
the module unlock being re-allocated and re-used for a lock inside of
a rcu-sched grace period. This is a very unlikely scenario, still
better plug the hole.

Use RCU list iteration in all places and ammend the comments.

Change lockdep_free_key_range() to issue a sync_sched() between
removal from the lists and returning -- which results in the memory
being freed. Further ensure the callers are placed correctly and
comment the requirements.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Tsyvarev <tsyvarev@ispras.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      35a9393c
    • B
      sched: Fix RLIMIT_RTTIME when PI-boosting to RT · 746db944
      由 Brian Silverman 提交于 
      When non-realtime tasks get priority-inheritance boosted to a realtime
scheduling class, RLIMIT_RTTIME starts to apply to them. However, the
counter used for checking this (the same one used for SCHED_RR
timeslices) was not getting reset. This meant that tasks running with a
non-realtime scheduling class which are repeatedly boosted to a realtime
one, but never block while they are running realtime, eventually hit the
timeout without ever running for a time over the limit. This patch
resets the realtime timeslice counter when un-PI-boosting from an RT to
a non-RT scheduling class.

I have some test code with two threads and a shared PTHREAD_PRIO_INHERIT
mutex which induces priority boosting and spins while boosted that gets
killed by a SIGXCPU on non-fixed kernels but doesn't with this patch
applied. It happens much faster with a CONFIG_PREEMPT_RT kernel, and
does happen eventually with PREEMPT_VOLUNTARY kernels.
Signed-off-by: NBrian Silverman <brian@peloton-tech.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: austin@peloton-tech.com
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1424305436-6716-1-git-send-email-brian@peloton-tech.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      746db944
    • P
      perf: Fix irq_work 'tail' recursion · d525211f
      由 Peter Zijlstra 提交于 
      Vince reported a watchdog lockup like:

	[<ffffffff8115e114>] perf_tp_event+0xc4/0x210
	[<ffffffff810b4f8a>] perf_trace_lock+0x12a/0x160
	[<ffffffff810b7f10>] lock_release+0x130/0x260
	[<ffffffff816c7474>] _raw_spin_unlock_irqrestore+0x24/0x40
	[<ffffffff8107bb4d>] do_send_sig_info+0x5d/0x80
	[<ffffffff811f69df>] send_sigio_to_task+0x12f/0x1a0
	[<ffffffff811f71ce>] send_sigio+0xae/0x100
	[<ffffffff811f72b7>] kill_fasync+0x97/0xf0
	[<ffffffff8115d0b4>] perf_event_wakeup+0xd4/0xf0
	[<ffffffff8115d103>] perf_pending_event+0x33/0x60
	[<ffffffff8114e3fc>] irq_work_run_list+0x4c/0x80
	[<ffffffff8114e448>] irq_work_run+0x18/0x40
	[<ffffffff810196af>] smp_trace_irq_work_interrupt+0x3f/0xc0
	[<ffffffff816c99bd>] trace_irq_work_interrupt+0x6d/0x80

Which is caused by an irq_work generating new irq_work and therefore
not allowing forward progress.

This happens because processing the perf irq_work triggers another
perf event (tracepoint stuff) which in turn generates an irq_work ad
infinitum.

Avoid this by raising the recursion counter in the irq_work -- which
effectively disables all software events (including tracepoints) from
actually triggering again.
Reported-by: NVince Weaver <vincent.weaver@maine.edu>
Tested-by: NVince Weaver <vincent.weaver@maine.edu>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20150219170311.GH21418@twins.programming.kicks-ass.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      d525211f
  9. 17 3月, 2015 1 次提交
    • P
      livepatch: Fix subtle race with coming and going modules · 8cb2c2dc
      由 Petr Mladek 提交于 
      There is a notifier that handles live patches for coming and going modules.
It takes klp_mutex lock to avoid races with coming and going patches but
it does not keep the lock all the time. Therefore the following races are
possible:

  1. The notifier is called sometime in STATE_MODULE_COMING. The module
     is visible by find_module() in this state all the time. It means that
     new patch can be registered and enabled even before the notifier is
     called. It might create wrong order of stacked patches, see below
     for an example.

   2. New patch could still see the module in the GOING state even after
      the notifier has been called. It will try to initialize the related
      object structures but the module could disappear at any time. There
      will stay mess in the structures. It might even cause an invalid
      memory access.

This patch solves the problem by adding a boolean variable into struct module.
The value is true after the coming and before the going handler is called.
New patches need to be applied when the value is true and they need to ignore
the module when the value is false.

Note that we need to know state of all modules on the system. The races are
related to new patches. Therefore we do not know what modules will get
patched.

Also note that we could not simply ignore going modules. The code from the
module could be called even in the GOING state until mod->exit() finishes.
If we start supporting patches with semantic changes between function
calls, we need to apply new patches to any still usable code.
See below for an example.

Finally note that the patch solves only the situation when a new patch is
registered. There are no such problems when the patch is being removed.
It does not matter who disable the patch first, whether the normal
disable_patch() or the module notifier. There is nothing to do
once the patch is disabled.

Alternative solutions:
======================

+ reject new patches when a patched module is coming or going; this is ugly

+ wait with adding new patch until the module leaves the COMING and GOING
  states; this might be dangerous and complicated; we would need to release
  kgr_lock in the middle of the patch registration to avoid a deadlock
  with the coming and going handlers; also we might need a waitqueue for
  each module which seems to be even bigger overhead than the boolean

+ stop modules from entering COMING and GOING states; wait until modules
  leave these states when they are already there; looks complicated; we would
  need to ignore the module that asked to stop the others to avoid a deadlock;
  also it is unclear what to do when two modules asked to stop others and
  both are in COMING state (situation when two new patches are applied)

+ always register/enable new patches and fix up the potential mess (registered
  patches order) in klp_module_init(); this is nasty and prone to regressions
  in the future development

+ add another MODULE_STATE where the kallsyms are visible but the module is not
  used yet; this looks too complex; the module states are checked on "many"
  locations

Example of patch stacking breakage:
===================================

The notifier could _not_ _simply_ ignore already initialized module objects.
For example, let's have three patches (P1, P2, P3) for functions a() and b()
where a() is from vmcore and b() is from a module M. Something like:

	a()	b()
P1	a1()	b1()
P2	a2()	b2()
P3	a3()	b3(3)

If you load the module M after all patches are registered and enabled.
The ftrace ops for function a() and b() has listed the functions in this
order:

	ops_a->func_stack -> list(a3,a2,a1)
	ops_b->func_stack -> list(b3,b2,b1)

, so the pointer to b3() is the first and will be used.

Then you might have the following scenario. Let's start with state when patches
P1 and P2 are registered and enabled but the module M is not loaded. Then ftrace
ops for b() does not exist. Then we get into the following race:

CPU0					CPU1

load_module(M)

  complete_formation()

  mod->state = MODULE_STATE_COMING;
  mutex_unlock(&module_mutex);

					klp_register_patch(P3);
					klp_enable_patch(P3);

					# STATE 1

  klp_module_notify(M)
    klp_module_notify_coming(P1);
    klp_module_notify_coming(P2);
    klp_module_notify_coming(P3);

					# STATE 2

The ftrace ops for a() and b() then looks:

  STATE1:

	ops_a->func_stack -> list(a3,a2,a1);
	ops_b->func_stack -> list(b3);

  STATE2:
	ops_a->func_stack -> list(a3,a2,a1);
	ops_b->func_stack -> list(b2,b1,b3);

therefore, b2() is used for the module but a3() is used for vmcore
because they were the last added.

Example of the race with going modules:
=======================================

CPU0					CPU1

delete_module()  #SYSCALL

   try_stop_module()
     mod->state = MODULE_STATE_GOING;

   mutex_unlock(&module_mutex);

					klp_register_patch()
					klp_enable_patch()

					#save place to switch universe

					b()     # from module that is going
					  a()   # from core (patched)

   mod->exit();

Note that the function b() can be called until we call mod->exit().

If we do not apply patch against b() because it is in MODULE_STATE_GOING,
it will call patched a() with modified semantic and things might get wrong.

[jpoimboe@redhat.com: use one boolean instead of two]
Signed-off-by: NPetr Mladek <pmladek@suse.cz>
Acked-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
      8cb2c2dc
  11. 13 3月, 2015 10 次提交
    • L
      perf: Fix context leak in put_event() · d415a7f1
      由 Leon Yu 提交于 
      Commit:

  a83fe28e ("perf: Fix put_event() ctx lock")

changed the locking logic in put_event() by replacing mutex_lock_nested()
with perf_event_ctx_lock_nested(), but didn't fix the subsequent
mutex_unlock() with a correct counterpart, perf_event_ctx_unlock().

Contexts are thus leaked as a result of incremented refcount
in perf_event_ctx_lock_nested().
Signed-off-by: NLeon Yu <chianglungyu@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Fixes: a83fe28e ("perf: Fix put_event() ctx lock")
Link: http://lkml.kernel.org/r/1424954613-5034-1-git-send-email-chianglungyu@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      d415a7f1
    • J
      clocksource: Rename __clocksource_updatefreq_*() to __clocksource_update_freq_*() · fba9e072
      由 John Stultz 提交于 
      Ingo requested this function be renamed to improve readability,
so I've renamed __clocksource_updatefreq_scale() as well as the
__clocksource_updatefreq_hz/khz() functions to avoid
squishedtogethernames.

This touches some of the sh clocksources, which I've not tested.

The arch/arm/plat-omap change is just a comment change for
consistency.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-13-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      fba9e072
    • J
      clocksource: Add some debug info about clocksources being registered · 8cc8c525
      由 John Stultz 提交于 
      Print the mask, max_cycles, and max_idle_ns values for
clocksources being registered.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-12-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8cc8c525
    • J
      clocksource: Mostly kill clocksource_register() · f8935983
      由 John Stultz 提交于 
      A long running project has been to clean up remaining uses
of clocksource_register(), replacing it with the simpler
clocksource_register_khz/hz() functions.

However, there are a few cases where we need to self-define
our mult/shift values, so switch the function to a more
obviously internal __clocksource_register() name, and
consolidate much of the internal logic so we don't have
duplication.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-10-git-send-email-john.stultz@linaro.org
[ Minor cleanups. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      f8935983
    • J
      clocksource: Improve clocksource watchdog reporting · 0b046b21
      由 John Stultz 提交于 
      The clocksource watchdog reporting has been less helpful
then desired, as it just printed the delta between
the two clocksources. This prevents any useful analysis
of why the skew occurred.

Thus this patch tries to improve the output when we
mark a clocksource as unstable, printing out the cycle
last and now values for both the current clocksource
and the watchdog clocksource. This will allow us to see
if the result was due to a false positive caused by
a problematic watchdog.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-9-git-send-email-john.stultz@linaro.org
[ Minor cleanups of kernel messages. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      0b046b21
    • J
      timekeeping: Add warnings when overflows or underflows are observed · 4ca22c26
      由 John Stultz 提交于 
      It was suggested that the underflow/overflow protection
should probably throw some sort of warning out, rather
than just silently fixing the issue.

So this patch adds some warnings here. The flag variables
used are not protected by locks, but since we can't print
from the reading functions, just being able to say we
saw an issue in the update interval is useful enough,
and can be slightly racy without real consequence.

The big complication is that we're only under a read
seqlock, so the data could shift under us during
our calculation to see if there was a problem. This
patch avoids this issue by nesting another seqlock
which allows us to snapshot the just required values
atomically. So we shouldn't see false positives.

I also added some basic rate-limiting here, since
on one build machine w/ skewed TSCs it was fairly
noisy at bootup.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-8-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      4ca22c26
    • J
      timekeeping: Try to catch clocksource delta underflows · 057b87e3
      由 John Stultz 提交于 
      In the case where there is a broken clocksource
where there are multiple actual clocks that
aren't perfectly aligned, we may see small "negative"
deltas when we subtract 'now' from 'cycle_last'.

The values are actually negative with respect to the
clocksource mask value, not necessarily negative
if cast to a s64, but we can check by checking the
delta to see if it is a small (relative to the mask)
negative value (again negative relative to the mask).

If so, we assume we jumped backwards somehow and
instead use zero for our delta.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-7-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      057b87e3
    • J
      timekeeping: Add checks to cap clocksource reads to the 'max_cycles' value · a558cd02
      由 John Stultz 提交于 
      When calculating the current delta since the last tick, we
currently have no hard protections to prevent a multiplication
overflow from occuring.

This patch introduces infrastructure to allow a cap that
limits the clocksource read delta value to the 'max_cycles' value,
which is where an overflow would occur.

Since this is in the hotpath, it adds the extra checking under
CONFIG_DEBUG_TIMEKEEPING=y.

There was some concern that capping time like this could cause
problems as we may stop expiring timers, which could go circular
if the timer that triggers time accumulation were mis-scheduled
too far in the future, which would cause time to stop.

However, since the mult overflow would result in a smaller time
value, we would effectively have the same problem there.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-6-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      a558cd02
    • J
      timekeeping: Add debugging checks to warn if we see delays · 3c17ad19
      由 John Stultz 提交于 
      Recently there's been requests for better sanity
checking in the time code, so that it's more clear
when something is going wrong, since timekeeping issues
could manifest in a large number of strange ways in
various subsystems.

Thus, this patch adds some extra infrastructure to
add a check to update_wall_time() to print two new
warnings:

 1) if we see the call delayed beyond the 'max_cycles'
    overflow point,

 2) or if we see the call delayed beyond the clocksource's
    'max_idle_ns' value, which is currently 50% of the
    overflow point.

This extra infrastructure is conditional on
a new CONFIG_DEBUG_TIMEKEEPING option, also
added in this patch - default off.

Tested this a bit by halting qemu for specified
lengths of time to trigger the warnings.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-5-git-send-email-john.stultz@linaro.org
[ Improved the changelog and the messages a bit. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      3c17ad19
    • A
      kasan, module, vmalloc: rework shadow allocation for modules · a5af5aa8
      由 Andrey Ryabinin 提交于 
      Current approach in handling shadow memory for modules is broken.

Shadow memory could be freed only after memory shadow corresponds it is no
longer used.  vfree() called from interrupt context could use memory its
freeing to store 'struct llist_node' in it:

    void vfree(const void *addr)
    {
    ...
        if (unlikely(in_interrupt())) {
            struct vfree_deferred *p = this_cpu_ptr(&vfree_deferred);
            if (llist_add((struct llist_node *)addr, &p->list))
                    schedule_work(&p->wq);

Later this list node used in free_work() which actually frees memory.
Currently module_memfree() called in interrupt context will free shadow
before freeing module's memory which could provoke kernel crash.

So shadow memory should be freed after module's memory.  However, such
deallocation order could race with kasan_module_alloc() in module_alloc().

Free shadow right before releasing vm area.  At this point vfree()'d
memory is not used anymore and yet not available for other allocations.
New VM_KASAN flag used to indicate that vm area has dynamically allocated
shadow memory so kasan frees shadow only if it was previously allocated.
Signed-off-by: NAndrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a5af5aa8
  13. 12 3月, 2015 2 次提交
    • J
      clocksource: Add 'max_cycles' to 'struct clocksource' · fb82fe2f
      由 John Stultz 提交于 
      In order to facilitate clocksource validation, add a
'max_cycles' field to the clocksource structure which
will hold the maximum cycle value that can safely be
multiplied without potentially causing an overflow.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-4-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      fb82fe2f
    • J
      clocksource: Simplify the logic around clocksource wrapping safety margins · 362fde04
      由 John Stultz 提交于 
      The clocksource logic has a number of places where we try to
include a safety margin. Most of these are 12% safety margins,
but they are inconsistently applied and sometimes are applied
on top of each other.

Additionally, in the previous patch, we corrected an issue
where we unintentionally in effect created a 50% safety margin,
which these 12.5% margins where then added to.

So to simplify the logic here, this patch removes the various
12.5% margins, and consolidates adding the margin in one place:
clocks_calc_max_nsecs().

Additionally, Linus prefers a 50% safety margin, as it allows
bad clock values to be more easily caught. This should really
have no net effect, due to the corrected issue earlier which
caused greater then 50% margins to be used w/o issue.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: Stephen Boyd <sboyd@codeaurora.org> (for the sched_clock.c bit)
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-3-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      362fde04