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commit 20841405940e7be0617612d521e206e4b6b325db upstream.
There are a few subtle races, between change_protection_range (used by
mprotect and change_prot_numa) on one side, and NUMA page migration and
compaction on the other side.
The basic race is that there is a time window between when the PTE gets
made non-present (PROT_NONE or NUMA), and the TLB is flushed.
During that time, a CPU may continue writing to the page.
This is fine most of the time, however compaction or the NUMA migration
code may come in, and migrate the page away.
When that happens, the CPU may continue writing, through the cached
translation, to what is no longer the current memory location of the
process.
This only affects x86, which has a somewhat optimistic pte_accessible.
All other architectures appear to be safe, and will either always flush,
or flush whenever there is a valid mapping, even with no permissions
(SPARC).
The basic race looks like this:
CPU A CPU B CPU C
load TLB entry
make entry PTE/PMD_NUMA
fault on entry
read/write old page
start migrating page
change PTE/PMD to new page
read/write old page [*]
flush TLB
reload TLB from new entry
read/write new page
lose data
[*] the old page may belong to a new user at this point!
The obvious fix is to flush remote TLB entries, by making sure that
pte_accessible aware of the fact that PROT_NONE and PROT_NUMA memory may
still be accessible if there is a TLB flush pending for the mm.
This should fix both NUMA migration and compaction.
[mgorman@suse.de: fix build]
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e0acd0a68ec7dbf6b7a81a87a867ebd7ac9b76c4 upstream.
This is only theoretical, but after try_to_wake_up(p) was changed
to check p->state under p->pi_lock the code like
__set_current_state(TASK_INTERRUPTIBLE);
schedule();
can miss a signal. This is the special case of wait-for-condition,
it relies on try_to_wake_up/schedule interaction and thus it does
not need mb() between __set_current_state() and if(signal_pending).
However, this __set_current_state() can move into the critical
section protected by rq->lock, now that try_to_wake_up() takes
another lock we need to ensure that it can't be reordered with
"if (signal_pending(current))" check inside that section.
The patch is actually one-liner, it simply adds smp_wmb() before
spin_lock_irq(rq->lock). This is what try_to_wake_up() already
does by the same reason.
We turn this wmb() into the new helper, smp_mb__before_spinlock(),
for better documentation and to allow the architectures to change
the default implementation.
While at it, kill smp_mb__after_lock(), it has no callers.
Perhaps we can also add smp_mb__before/after_spinunlock() for
prepare_to_wait().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 85fbd722ad0f5d64d1ad15888cd1eb2188bfb557 upstream.
Freezable kthreads and workqueues are fundamentally problematic in
that they effectively introduce a big kernel lock widely used in the
kernel and have already been the culprit of several deadlock
scenarios. This is the latest occurrence.
During resume, libata rescans all the ports and revalidates all
pre-existing devices. If it determines that a device has gone
missing, the device is removed from the system which involves
invalidating block device and flushing bdi while holding driver core
layer locks. Unfortunately, this can race with the rest of device
resume. Because freezable kthreads and workqueues are thawed after
device resume is complete and block device removal depends on
freezable workqueues and kthreads (e.g. bdi_wq, jbd2) to make
progress, this can lead to deadlock - block device removal can't
proceed because kthreads are frozen and kthreads can't be thawed
because device resume is blocked behind block device removal.
839a8e8660b6 ("writeback: replace custom worker pool implementation
with unbound workqueue") made this particular deadlock scenario more
visible but the underlying problem has always been there - the
original forker task and jbd2 are freezable too. In fact, this is
highly likely just one of many possible deadlock scenarios given that
freezer behaves as a big kernel lock and we don't have any debug
mechanism around it.
I believe the right thing to do is getting rid of freezable kthreads
and workqueues. This is something fundamentally broken. For now,
implement a funny workaround in libata - just avoid doing block device
hot[un]plug while the system is frozen. Kernel engineering at its
finest. :(
v2: Add EXPORT_SYMBOL_GPL(pm_freezing) for cases where libata is built
as a module.
v3: Comment updated and polling interval changed to 10ms as suggested
by Rafael.
v4: Add #ifdef CONFIG_FREEZER around the hack as pm_freezing is not
defined when FREEZER is not configured thus breaking build.
Reported by kbuild test robot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Tomaž Šolc <tomaz.solc@tablix.org>
Reviewed-by: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=62801
Link: http://lkml.kernel.org/r/20131213174932.GA27070@htj.dyndns.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 757dfcaa41844595964f1220f1d33182dae49976 upstream.
This patch touches the RT group scheduling case.
Functions inc_rt_prio_smp() and dec_rt_prio_smp() change (global) rq's
priority, while rt_rq passed to them may be not the top-level rt_rq.
This is wrong, because changing of priority on a child level does not
guarantee that the priority is the highest all over the rq. So, this
leak makes RT balancing unusable.
The short example: the task having the highest priority among all rq's
RT tasks (no one other task has the same priority) are waking on a
throttle rt_rq. The rq's cpupri is set to the task's priority
equivalent, but real rq->rt.highest_prio.curr is less.
The patch below fixes the problem.
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
CC: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/49231385567953@web4m.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3c67f474558748b604e247d92b55dfe89654c81d upstream.
Inaccessible VMA should not be trapping NUMA hint faults. Skip them.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c4602c1c818bd6626178d6d3fcc152d9f2f48ac0 upstream.
Ftrace currently initializes only the online CPUs. This implementation has
two problems:
- If we online a CPU after we enable the function profile, and then run the
test, we will lose the trace information on that CPU.
Steps to reproduce:
# echo 0 > /sys/devices/system/cpu/cpu1/online
# cd <debugfs>/tracing/
# echo <some function name> >> set_ftrace_filter
# echo 1 > function_profile_enabled
# echo 1 > /sys/devices/system/cpu/cpu1/online
# run test
- If we offline a CPU before we enable the function profile, we will not clear
the trace information when we enable the function profile. It will trouble
the users.
Steps to reproduce:
# cd <debugfs>/tracing/
# echo <some function name> >> set_ftrace_filter
# echo 1 > function_profile_enabled
# run test
# cat trace_stat/function*
# echo 0 > /sys/devices/system/cpu/cpu1/online
# echo 0 > function_profile_enabled
# echo 1 > function_profile_enabled
# cat trace_stat/function*
# run test
# cat trace_stat/function*
So it is better that we initialize the ftrace profiler for each possible cpu
every time we enable the function profile instead of just the online ones.
Link: http://lkml.kernel.org/r/1387178401-10619-1-git-send-email-miaox@cn.fujitsu.com
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f9f9ffc237dd924f048204e8799da74f9ecf40cf upstream.
throttle_cfs_rq() doesn't check to make sure that period_timer is running,
and while update_curr/assign_cfs_runtime does, a concurrently running
period_timer on another cpu could cancel itself between this cpu's
update_curr and throttle_cfs_rq(). If there are no other cfs_rqs running
in the tg to restart the timer, this causes the cfs_rq to be stranded
forever.
Fix this by calling __start_cfs_bandwidth() in throttle if the timer is
inactive.
(Also add some sched_debug lines for cfs_bandwidth.)
Tested: make a run/sleep task in a cgroup, loop switching the cgroup
between 1ms/100ms quota and unlimited, checking for timer_active=0 and
throttled=1 as a failure. With the throttle_cfs_rq() change commented out
this fails, with the full patch it passes.
Signed-off-by: Ben Segall <bsegall@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/20131016181632.22647.84174.stgit@sword-of-the-dawn.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f12d5bfceb7e1f9051563381ec047f7f13956c3c upstream.
The hugepage code had the exact same bug that regular pages had in
commit 7485d0d3758e ("futexes: Remove rw parameter from
get_futex_key()").
The regular page case was fixed by commit 9ea71503a8ed ("futex: Fix
regression with read only mappings"), but the transparent hugepage case
(added in a5b338f2b0b1: "thp: update futex compound knowledge") case
remained broken.
Found by Dave Jones and his trinity tool.
Reported-and-tested-by: Dave Jones <davej@fedoraproject.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4fc9bbf98fd66f879e628d8537ba7c240be2b58e upstream.
Add a flag to tell the PCI subsystem that kernel is shutting down in
preparation to kexec a kernel. Add code in PCI subsystem to use this flag
to clear Bus Master bit on PCI devices only in case of kexec reboot.
This fixes a power-off problem on Acer Aspire V5-573G and likely other
machines and avoids any other issues caused by clearing Bus Master bit on
PCI devices in normal shutdown path. The problem was introduced by
b566a22c2332 ("PCI: disable Bus Master on PCI device shutdown").
This patch is based on discussion at
http://marc.info/?l=linux-pci&m=138425645204355&w=2
Link: https://bugzilla.kernel.org/show_bug.cgi?id=63861
Reported-by: Chang Liu <cl91tp@gmail.com>
Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ac01810c9d2814238f08a227062e66a35a0e1ea2 upstream.
When the system enters suspend, it disables all interrupts in
suspend_device_irqs(), including the interrupts marked EARLY_RESUME.
On the resume side things are different. The EARLY_RESUME interrupts
are reenabled in sys_core_ops->resume and the non EARLY_RESUME
interrupts are reenabled in the normal system resume path.
When suspend_noirq() failed or suspend is aborted for any other
reason, we might omit the resume side call to sys_core_ops->resume()
and therefor the interrupts marked EARLY_RESUME are not reenabled and
stay disabled forever.
To solve this, enable all irqs unconditionally in irq_resume()
regardless whether interrupts marked EARLY_RESUMEhave been already
enabled or not.
This might try to reenable already enabled interrupts in the non
failure case, but the only affected platform is XEN and it has been
confirmed that it does not cause any side effects.
[ tglx: Massaged changelog. ]
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by-and-tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Cc: <ian.campbell@citrix.com>
Cc: <rjw@rjwysocki.net>
Cc: <len.brown@intel.com>
Cc: <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/1385388587-16442-1-git-send-email-ldewangan@nvidia.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4be77398ac9d948773116b6be4a3c91b3d6ea18c upstream.
Since commit 1e75fa8be9f (time: Condense timekeeper.xtime
into xtime_sec - merged in v3.6), there has been an problem
with the error accounting in the timekeeping code, such that
when truncating to nanoseconds, we round up to the next nsec,
but the balancing adjustment to the ntp_error value was dropped.
This causes 1ns per tick drift forward of the clock.
In 3.7, this logic was isolated to only GENERIC_TIME_VSYSCALL_OLD
architectures (s390, ia64, powerpc).
The fix is simply to balance the accounting and to subtract the
added nanosecond from ntp_error. This allows the internal long-term
clock steering to keep the clock accurate.
While this fix removes the regression added in 1e75fa8be9f, the
ideal solution is to move away from GENERIC_TIME_VSYSCALL_OLD
and use the new VSYSCALL method, which avoids entirely the
nanosecond granular rounding, and the resulting short-term clock
adjustment oscillation needed to keep long term accurate time.
[ jstultz: Many thanks to Martin for his efforts identifying this
subtle bug, and providing the fix. ]
Originally-from: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1385149491-20307-1-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a97ad0c4b447a132a322cedc3a5f7fa4cab4b304 upstream.
The current code requires that the scheduled update of the RTC happens
in the closest tick to the half of the second. This seems to be
difficult to achieve reliably. The scheduled work may be missing the
target time by a tick or two and be constantly rescheduled every second.
Relax the limit to 10 ticks. As a typical RTC drifts in the 11-minute
update interval by several milliseconds, this shouldn't affect the
overall accuracy of the RTC much.
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 70e5975d3a04be5479a28eec4a2fb10f98ad2785 upstream.
On an SMP system with only one global clockevent and a dummy
clockevent per CPU we run into problems. We want the dummy
clockevents to be registered as the per CPU tick devices, but
we can only achieve that if we register the dummy clockevents
before the global clockevent or if we artificially inflate the
rating of the dummy clockevents to be higher than the rating
of the global clockevent. Failure to do so leads to boot
hangs when the dummy timers are registered on all other CPUs
besides the CPU that accepted the global clockevent as its tick
device and there is no broadcast timer to poke the dummy
devices.
If we're registering multiple clockevents and one clockevent is
global and the other is local to a particular CPU we should
choose to use the local clockevent regardless of the rating of
the device. This way, if the clockevent is a dummy it will take
the tick device duty as long as there isn't a higher rated tick
device and any global clockevent will be bumped out into
broadcast mode, fixing the problem described above.
Reported-and-tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: soren.brinkmann@xilinx.com
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20130613183950.GA32061@codeaurora.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kim Phillips <kim.phillips@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 45cb8e01b2ecef1c2afb18333e95793fa1a90281 upstream.
Split out the clockevent device selection logic. Preparatory patch to
allow unbinding active clockevent devices.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.431796247@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kim Phillips <kim.phillips@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ccf33d6880f39a35158fff66db13000ae4943fac upstream.
We want to be able to remove clockevent modules as well. Add a
refcount so we don't remove a module with an active clock event
device.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.307435149@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kim Phillips <kim.phillips@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7172a286ced0c1f4f239a0fa09db54ed37d3ead2 upstream.
7+ years and still a single user. Kill it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.098520211@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Kim Phillips <kim.phillips@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e5fca243abae1445afbfceebda5f08462ef869d3 upstream.
Since be44562613851 ("cgroup: remove synchronize_rcu() from
cgroup_diput()"), cgroup destruction path makes use of workqueue. css
freeing is performed from a work item from that point on and a later
commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two
steps"), moves css offlining to workqueue too.
As cgroup destruction isn't depended upon for memory reclaim, the
destruction work items were put on the system_wq; unfortunately, some
controller may block in the destruction path for considerable duration
while holding cgroup_mutex. As large part of destruction path is
synchronized through cgroup_mutex, when combined with high rate of
cgroup removals, this has potential to fill up system_wq's max_active
of 256.
Also, it turns out that memcg's css destruction path ends up queueing
and waiting for work items on system_wq through work_on_cpu(). If
such operation happens while system_wq is fully occupied by cgroup
destruction work items, work_on_cpu() can't make forward progress
because system_wq is full and other destruction work items on
system_wq can't make forward progress because the work item waiting
for work_on_cpu() is holding cgroup_mutex, leading to deadlock.
This can be fixed by queueing destruction work items on a separate
workqueue. This patch creates a dedicated workqueue -
cgroup_destroy_wq - for this purpose. As these work items shouldn't
have inter-dependencies and mostly serialized by cgroup_mutex anyway,
giving high concurrency level doesn't buy anything and the workqueue's
@max_active is set to 1 so that destruction work items are executed
one by one on each CPU.
Hugh Dickins: Because cgroup_init() is run before init_workqueues(),
cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a
separate core_initcall(). In the future, we probably want to reorder
so that workqueue init happens before cgroup_init().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Hugh Dickins <hughd@google.com>
Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com>
Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com
Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0fc0287c9ed1ffd3706f8b4d9b314aa102ef1245 upstream.
Juri hit the below lockdep report:
[ 4.303391] ======================================================
[ 4.303392] [ INFO: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected ]
[ 4.303394] 3.12.0-dl-peterz+ #144 Not tainted
[ 4.303395] ------------------------------------------------------
[ 4.303397] kworker/u4:3/689 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[ 4.303399] (&p->mems_allowed_seq){+.+...}, at: [<ffffffff8114e63c>] new_slab+0x6c/0x290
[ 4.303417]
[ 4.303417] and this task is already holding:
[ 4.303418] (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff812d2dfb>] blk_execute_rq_nowait+0x5b/0x100
[ 4.303431] which would create a new lock dependency:
[ 4.303432] (&(&q->__queue_lock)->rlock){..-...} -> (&p->mems_allowed_seq){+.+...}
[ 4.303436]
[ 4.303898] the dependencies between the lock to be acquired and SOFTIRQ-irq-unsafe lock:
[ 4.303918] -> (&p->mems_allowed_seq){+.+...} ops: 2762 {
[ 4.303922] HARDIRQ-ON-W at:
[ 4.303923] [<ffffffff8108ab9a>] __lock_acquire+0x65a/0x1ff0
[ 4.303926] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140
[ 4.303929] [<ffffffff81063dd6>] kthreadd+0x86/0x180
[ 4.303931] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0
[ 4.303933] SOFTIRQ-ON-W at:
[ 4.303933] [<ffffffff8108abcc>] __lock_acquire+0x68c/0x1ff0
[ 4.303935] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140
[ 4.303940] [<ffffffff81063dd6>] kthreadd+0x86/0x180
[ 4.303955] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0
[ 4.303959] INITIAL USE at:
[ 4.303960] [<ffffffff8108a884>] __lock_acquire+0x344/0x1ff0
[ 4.303963] [<ffffffff8108cbe3>] lock_acquire+0x93/0x140
[ 4.303966] [<ffffffff81063dd6>] kthreadd+0x86/0x180
[ 4.303969] [<ffffffff816ded6c>] ret_from_fork+0x7c/0xb0
[ 4.303972] }
Which reports that we take mems_allowed_seq with interrupts enabled. A
little digging found that this can only be from
cpuset_change_task_nodemask().
This is an actual deadlock because an interrupt doing an allocation will
hit get_mems_allowed()->...->__read_seqcount_begin(), which will spin
forever waiting for the write side to complete.
Cc: John Stultz <john.stultz@linaro.org>
Cc: Mel Gorman <mgorman@suse.de>
Reported-by: Juri Lelli <juri.lelli@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Juri Lelli <juri.lelli@gmail.com>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8a2b75384444488fc4f2cbb9f0921b6a0794838f upstream.
An ordered workqueue implements execution ordering by using single
pool_workqueue with max_active == 1. On a given pool_workqueue, work
items are processed in FIFO order and limiting max_active to 1
enforces the queued work items to be processed one by one.
Unfortunately, 4c16bd327c ("workqueue: implement NUMA affinity for
unbound workqueues") accidentally broke this guarantee by applying
NUMA affinity to ordered workqueues too. On NUMA setups, an ordered
workqueue would end up with separate pool_workqueues for different
nodes. Each pool_workqueue still limits max_active to 1 but multiple
work items may be executed concurrently and out of order depending on
which node they are queued to.
Fix it by using dedicated ordered_wq_attrs[] when creating ordered
workqueues. The new attrs match the unbound ones except that no_numa
is always set thus forcing all NUMA nodes to share the default
pool_workqueue.
While at it, add sanity check in workqueue creation path which
verifies that an ordered workqueues has only the default
pool_workqueue.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Libin <huawei.libin@huawei.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8a56d7761d2d041ae5e8215d20b4167d8aa93f51 upstream.
Commit 8c4f3c3fa9681 "ftrace: Check module functions being traced on reload"
fixed module loading and unloading with respect to function tracing, but
it missed the function graph tracer. If you perform the following
# cd /sys/kernel/debug/tracing
# echo function_graph > current_tracer
# modprobe nfsd
# echo nop > current_tracer
You'll get the following oops message:
------------[ cut here ]------------
WARNING: CPU: 2 PID: 2910 at /linux.git/kernel/trace/ftrace.c:1640 __ftrace_hash_rec_update.part.35+0x168/0x1b9()
Modules linked in: nfsd exportfs nfs_acl lockd ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables uinput snd_hda_codec_idt
CPU: 2 PID: 2910 Comm: bash Not tainted 3.13.0-rc1-test #7
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
0000000000000668 ffff8800787efcf8 ffffffff814fe193 ffff88007d500000
0000000000000000 ffff8800787efd38 ffffffff8103b80a 0000000000000668
ffffffff810b2b9a ffffffff81a48370 0000000000000001 ffff880037aea000
Call Trace:
[<ffffffff814fe193>] dump_stack+0x4f/0x7c
[<ffffffff8103b80a>] warn_slowpath_common+0x81/0x9b
[<ffffffff810b2b9a>] ? __ftrace_hash_rec_update.part.35+0x168/0x1b9
[<ffffffff8103b83e>] warn_slowpath_null+0x1a/0x1c
[<ffffffff810b2b9a>] __ftrace_hash_rec_update.part.35+0x168/0x1b9
[<ffffffff81502f89>] ? __mutex_lock_slowpath+0x364/0x364
[<ffffffff810b2cc2>] ftrace_shutdown+0xd7/0x12b
[<ffffffff810b47f0>] unregister_ftrace_graph+0x49/0x78
[<ffffffff810c4b30>] graph_trace_reset+0xe/0x10
[<ffffffff810bf393>] tracing_set_tracer+0xa7/0x26a
[<ffffffff810bf5e1>] tracing_set_trace_write+0x8b/0xbd
[<ffffffff810c501c>] ? ftrace_return_to_handler+0xb2/0xde
[<ffffffff811240a8>] ? __sb_end_write+0x5e/0x5e
[<ffffffff81122aed>] vfs_write+0xab/0xf6
[<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85
[<ffffffff81122dbd>] SyS_write+0x59/0x82
[<ffffffff8150a185>] ftrace_graph_caller+0x85/0x85
[<ffffffff8150a2d2>] system_call_fastpath+0x16/0x1b
---[ end trace 940358030751eafb ]---
The above mentioned commit didn't go far enough. Well, it covered the
function tracer by adding checks in __register_ftrace_function(). The
problem is that the function graph tracer circumvents that (for a slight
efficiency gain when function graph trace is running with a function
tracer. The gain was not worth this).
The problem came with ftrace_startup() which should always be called after
__register_ftrace_function(), if you want this bug to be completely fixed.
Anyway, this solution moves __register_ftrace_function() inside of
ftrace_startup() and removes the need to call them both.
Reported-by: Dave Wysochanski <dwysocha@redhat.com>
Fixes: ed926f9b35cd ("ftrace: Use counters to enable functions to trace")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d3aea84a4ace5ff9ce7fb7714cee07bebef681c2 upstream.
...to make it clear what the intent behind each record's operation was.
In many cases you can infer this, based on the context of the syscall
and the result. In other cases it's not so obvious. For instance, in
the case where you have a file being renamed over another, you'll have
two different records with the same filename but different inode info.
By logging this information we can clearly tell which one was created
and which was deleted.
This fixes what was broken in commit bfcec708.
Commit 79f6530c should also be backported to stable v3.7+.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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audit_names record
commit 79f6530cb59e2a0af6953742a33cc29e98ca631c upstream.
The old audit PATH records for mq_open looked like this:
type=PATH msg=audit(1366282323.982:869): item=1 name=(null) inode=6777
dev=00:0c mode=041777 ouid=0 ogid=0 rdev=00:00
obj=system_u:object_r:tmpfs_t:s15:c0.c1023
type=PATH msg=audit(1366282323.982:869): item=0 name="test_mq" inode=26732
dev=00:0c mode=0100700 ouid=0 ogid=0 rdev=00:00
obj=staff_u:object_r:user_tmpfs_t:s15:c0.c1023
...with the audit related changes that went into 3.7, they now look like this:
type=PATH msg=audit(1366282236.776:3606): item=2 name=(null) inode=66655
dev=00:0c mode=0100700 ouid=0 ogid=0 rdev=00:00
obj=staff_u:object_r:user_tmpfs_t:s15:c0.c1023
type=PATH msg=audit(1366282236.776:3606): item=1 name=(null) inode=6926
dev=00:0c mode=041777 ouid=0 ogid=0 rdev=00:00
obj=system_u:object_r:tmpfs_t:s15:c0.c1023
type=PATH msg=audit(1366282236.776:3606): item=0 name="test_mq"
Both of these look wrong to me. As Steve Grubb pointed out:
"What we need is 1 PATH record that identifies the MQ. The other PATH
records probably should not be there."
Fix it to record the mq root as a parent, and flag it such that it
should be hidden from view when the names are logged, since the root of
the mq filesystem isn't terribly interesting. With this change, we get
a single PATH record that looks more like this:
type=PATH msg=audit(1368021604.836:484): item=0 name="test_mq" inode=16914
dev=00:0c mode=0100644 ouid=0 ogid=0 rdev=00:00
obj=unconfined_u:object_r:user_tmpfs_t:s0
In order to do this, a new audit_inode_parent_hidden() function is
added. If we do it this way, then we avoid having the existing callers
of audit_inode needing to do any sort of flag conversion if auditing is
inactive.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reported-by: Jiri Jaburek <jjaburek@redhat.com>
Cc: Steve Grubb <sgrubb@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 64fbff9ae0a0a843365d922e0057fc785f23f0e3 upstream.
We leak 4 bytes of kernel stack in response to an AUDIT_GET request as
we miss to initialize the mask member of status_set. Fix that.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 4d8fe7376a12bf4524783dd95cbc00f1fece6232 upstream.
Using the nlmsg_len member of the netlink header to test if the message
is valid is wrong as it includes the size of the netlink header itself.
Thereby allowing to send short netlink messages that pass those checks.
Use nlmsg_len() instead to test for the right message length. The result
of nlmsg_len() is guaranteed to be non-negative as the netlink message
already passed the checks of nlmsg_ok().
Also switch to min_t() to please checkpatch.pl.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 0868a5e150bc4c47e7a003367cd755811eb41e0b upstream.
When the audit=1 kernel parameter is absent and auditd is not running,
AUDIT_USER_AVC messages are being silently discarded.
AUDIT_USER_AVC messages should be sent to userspace using printk(), as
mentioned in the commit message of 4a4cd633 ("AUDIT: Optimise the
audit-disabled case for discarding user messages").
When audit_enabled is 0, audit_receive_msg() discards all user messages
except for AUDIT_USER_AVC messages. However, audit_log_common_recv_msg()
refuses to allocate an audit_buffer if audit_enabled is 0. The fix is to
special case AUDIT_USER_AVC messages in both functions.
It looks like commit 50397bd1 ("[AUDIT] clean up audit_receive_msg()")
introduced this bug.
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: linux-audit@redhat.com
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit fd432b9f8c7c88428a4635b9f5a9c6e174df6e36 upstream.
When system has a lot of highmem (e.g. 16GiB using a 32 bits kernel),
the code to calculate how much memory we need to preallocate in
normal zone may cause overflow. As Leon has analysed:
It looks that during computing 'alloc' variable there is overflow:
alloc = (3943404 - 1970542) - 1978280 = -5418 (signed)
And this function goes to err_out.
Fix this by avoiding that overflow.
References: https://bugzilla.kernel.org/show_bug.cgi?id=60817
Reported-and-tested-by: Leon Drugi <eyak@wp.pl>
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 98d6f4dd84a134d942827584a3c5f67ffd8ec35f upstream.
Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide
on ARM. (http://bugs.ruby-lang.org/issues/9008)
Because of, commit 1c6b39ad3f (alarmtimers: Return -ENOTSUPP if no
RTC device is present) intruduced to return ENOTSUPP when
clock_get{time,res} can't find a RTC device. However this is incorrect.
First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the
closest userland equivlents).
Second, Posix and Linux man pages agree that clock_gettime and
clock_getres should return EINVAL if clk_id argument is invalid.
While the arugment that the clockid is valid, but just not supported
on this hardware could be made, this is just a technicality that
doesn't help userspace applicaitons, and only complicates error
handling.
Thus, this patch changes the code to use EINVAL.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Reported-by: Vit Ondruch <v.ondruch@tiscali.cz>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
[jstultz: Tweaks to commit message to include full rational]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d049f74f2dbe71354d43d393ac3a188947811348 upstream.
The get_dumpable() return value is not boolean. Most users of the
function actually want to be testing for non-SUID_DUMP_USER(1) rather than
SUID_DUMP_DISABLE(0). The SUID_DUMP_ROOT(2) is also considered a
protected state. Almost all places did this correctly, excepting the two
places fixed in this patch.
Wrong logic:
if (dumpable == SUID_DUMP_DISABLE) { /* be protective */ }
or
if (dumpable == 0) { /* be protective */ }
or
if (!dumpable) { /* be protective */ }
Correct logic:
if (dumpable != SUID_DUMP_USER) { /* be protective */ }
or
if (dumpable != 1) { /* be protective */ }
Without this patch, if the system had set the sysctl fs/suid_dumpable=2, a
user was able to ptrace attach to processes that had dropped privileges to
that user. (This may have been partially mitigated if Yama was enabled.)
The macros have been moved into the file that declares get/set_dumpable(),
which means things like the ia64 code can see them too.
CVE-2013-2929
Reported-by: Vasily Kulikov <segoon@openwall.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 12ae030d54ef250706da5642fc7697cc60ad0df7 upstream.
The current default perf paranoid level is "1" which has
"perf_paranoid_kernel()" return false, and giving any operations that
use it, access to normal users. Unfortunately, this includes function
tracing and normal users should not be allowed to enable function
tracing by default.
The proper level is defined at "-1" (full perf access), which
"perf_paranoid_tracepoint_raw()" will only give access to. Use that
check instead for enabling function tracing.
Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
CVE: CVE-2013-2930
Fixes: ced39002f5ea ("ftrace, perf: Add support to use function tracepoint in perf")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ea8117478918a4734586d35ff530721b682425be upstream.
Mike reported that commit 7d1a9417 ("x86: Use generic idle loop")
regressed several workloads and caused excessive reschedule
interrupts.
The patch in question failed to notice that the x86 code had an
inverted sense of the polling state versus the new generic code (x86:
default polling, generic: default !polling).
Fix the two prominent x86 mwait based idle drivers and introduce a few
new generic polling helpers (fixing the wrong smp_mb__after_clear_bit
usage).
Also switch the idle routines to using tif_need_resched() which is an
immediate TIF_NEED_RESCHED test as opposed to need_resched which will
end up being slightly different.
Reported-by: Mike Galbraith <bitbucket@online.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: lenb@kernel.org
Cc: tglx@linutronix.de
Link: http://lkml.kernel.org/n/tip-nc03imb0etuefmzybzj7sprf@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit bf378d341e4873ed928dc3c636252e6895a21f50 upstream.
The PPC64 people noticed a missing memory barrier and crufty old
comments in the perf ring buffer code. So update all the comments and
add the missing barrier.
When the architecture implements local_t using atomic_long_t there
will be double barriers issued; but short of introducing more
conditional barrier primitives this is the best we can do.
Reported-by: Victor Kaplansky <victork@il.ibm.com>
Tested-by: Victor Kaplansky <victork@il.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: michael@ellerman.id.au
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: anton@samba.org
Cc: benh@kernel.crashing.org
Link: http://lkml.kernel.org/r/20131025173749.GG19466@laptop.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 057db8488b53d5e4faa0cedb2f39d4ae75dfbdbb upstream.
Andrey reported the following report:
ERROR: AddressSanitizer: heap-buffer-overflow on address ffff8800359c99f3
ffff8800359c99f3 is located 0 bytes to the right of 243-byte region [ffff8800359c9900, ffff8800359c99f3)
Accessed by thread T13003:
#0 ffffffff810dd2da (asan_report_error+0x32a/0x440)
#1 ffffffff810dc6b0 (asan_check_region+0x30/0x40)
#2 ffffffff810dd4d3 (__tsan_write1+0x13/0x20)
#3 ffffffff811cd19e (ftrace_regex_release+0x1be/0x260)
#4 ffffffff812a1065 (__fput+0x155/0x360)
#5 ffffffff812a12de (____fput+0x1e/0x30)
#6 ffffffff8111708d (task_work_run+0x10d/0x140)
#7 ffffffff810ea043 (do_exit+0x433/0x11f0)
#8 ffffffff810eaee4 (do_group_exit+0x84/0x130)
#9 ffffffff810eafb1 (SyS_exit_group+0x21/0x30)
#10 ffffffff81928782 (system_call_fastpath+0x16/0x1b)
Allocated by thread T5167:
#0 ffffffff810dc778 (asan_slab_alloc+0x48/0xc0)
#1 ffffffff8128337c (__kmalloc+0xbc/0x500)
#2 ffffffff811d9d54 (trace_parser_get_init+0x34/0x90)
#3 ffffffff811cd7b3 (ftrace_regex_open+0x83/0x2e0)
#4 ffffffff811cda7d (ftrace_filter_open+0x2d/0x40)
#5 ffffffff8129b4ff (do_dentry_open+0x32f/0x430)
#6 ffffffff8129b668 (finish_open+0x68/0xa0)
#7 ffffffff812b66ac (do_last+0xb8c/0x1710)
#8 ffffffff812b7350 (path_openat+0x120/0xb50)
#9 ffffffff812b8884 (do_filp_open+0x54/0xb0)
#10 ffffffff8129d36c (do_sys_open+0x1ac/0x2c0)
#11 ffffffff8129d4b7 (SyS_open+0x37/0x50)
#12 ffffffff81928782 (system_call_fastpath+0x16/0x1b)
Shadow bytes around the buggy address:
ffff8800359c9700: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
ffff8800359c9780: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
ffff8800359c9800: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9880: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>ffff8800359c9980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00[03]fb
ffff8800359c9a00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9a80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
ffff8800359c9b00: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
ffff8800359c9b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8800359c9c00: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap redzone: fa
Heap kmalloc redzone: fb
Freed heap region: fd
Shadow gap: fe
The out-of-bounds access happens on 'parser->buffer[parser->idx] = 0;'
Although the crash happened in ftrace_regex_open() the real bug
occurred in trace_get_user() where there's an incrementation to
parser->idx without a check against the size. The way it is triggered
is if userspace sends in 128 characters (EVENT_BUF_SIZE + 1), the loop
that reads the last character stores it and then breaks out because
there is no more characters. Then the last character is read to determine
what to do next, and the index is incremented without checking size.
Then the caller of trace_get_user() usually nulls out the last character
with a zero, but since the index is equal to the size, it writes a nul
character after the allocated space, which can corrupt memory.
Luckily, only root user has write access to this file.
Link: http://lkml.kernel.org/r/20131009222323.04fd1a0d@gandalf.local.home
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 97b9410643475d6557d2517c2aff9fd2221141a9 upstream.
Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use
clockevents_config_and_register() where possible" caused a regression
for some of the converted subarchs.
The reason is, that the clockevents core code converts the minimal
hardware tick delta to a nanosecond value for core internal
usage. This conversion is affected by integer math rounding loss, so
the backwards conversion to hardware ticks will likely result in a
value which is less than the configured hardware limitation. The
affected subarchs used their own workaround (SIGH!) which got lost in
the conversion.
The solution for the issue at hand is simple: adding evt->mult - 1 to
the shifted value before the integer divison in the core conversion
function takes care of it. But this only works for the case where for
the scaled math mult/shift pair "mult <= 1 << shift" is true. For the
case where "mult > 1 << shift" we can apply the rounding add only for
the minimum delta value to make sure that the backward conversion is
not less than the given hardware limit. For the upper bound we need to
omit the rounding add, because the backwards conversion is always
larger than the original latch value. That would violate the upper
bound of the hardware device.
Though looking closer at the details of that function reveals another
bogosity: The upper bounds check is broken as well. Checking for a
resulting "clc" value greater than KTIME_MAX after the conversion is
pointless. The conversion does:
u64 clc = (latch << evt->shift) / evt->mult;
So there is no sanity check for (latch << evt->shift) exceeding the
64bit boundary. The latch argument is "unsigned long", so on a 64bit
arch the handed in argument could easily lead to an unnoticed shift
overflow. With the above rounding fix applied the calculation before
the divison is:
u64 clc = (latch << evt->shift) + evt->mult - 1;
So we need to make sure, that neither the shift nor the rounding add
is overflowing the u64 boundary.
[ukl: move assignment to rnd after eventually changing mult, fix build
issue and correct comment with the right math]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: nicolas.ferre@atmel.com
Cc: Marc Pignat <marc.pignat@hevs.ch>
Cc: john.stultz@linaro.org
Cc: kernel@pengutronix.de
Cc: Ronald Wahl <ronald.wahl@raritan.com>
Cc: LAK <linux-arm-kernel@lists.infradead.org>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit ea84753c98a7ac6b74e530b64c444a912b3835ca upstream.
Both Anjana and Eunki reported a stall in the while_each_thread loop
in cgroup_attach_task().
It's because, when we attach a single thread to a cgroup, if the cgroup
is exiting or is already in that cgroup, we won't break the loop.
If the task is already in the cgroup, the bug can lead to another thread
being attached to the cgroup unexpectedly:
# echo 5207 > tasks
# cat tasks
5207
# echo 5207 > tasks
# cat tasks
5207
5215
What's worse, if the task to be attached isn't the leader of the thread
group, we might never exit the loop, hence cpu stall. Thanks for Oleg's
analysis.
This bug was introduced by commit 081aa458c38ba576bdd4265fc807fa95b48b9e79
("cgroup: consolidate cgroup_attach_task() and cgroup_attach_proc()")
[ lizf: - fixed the first continue, pointed out by Oleg,
- rewrote changelog. ]
Reported-by: Eunki Kim <eunki_kim@samsung.com>
Reported-by: Anjana V Kumar <anjanavk12@gmail.com>
Signed-off-by: Anjana V Kumar <anjanavk12@gmail.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit ded797547548a5b8e7b92383a41e4c0e6b0ecb7f upstream.
The commit facd8b80c67a3cf64a467c4a2ac5fb31f2e6745b
("irq: Sanitize invoke_softirq") converted irq exit
calls of do_softirq() to __do_softirq() on all architectures,
assuming it was only used there for its irq disablement
properties.
But as a side effect, the softirqs processed in the end
of the hardirq are always called on the inline current
stack that is used by irq_exit() instead of the softirq
stack provided by the archs that override do_softirq().
The result is mostly safe if the architecture runs irq_exit()
on a separate irq stack because then softirqs are processed
on that same stack that is near empty at this stage (assuming
hardirq aren't nesting).
Otherwise irq_exit() runs in the task stack and so does the softirq
too. The interrupted call stack can be randomly deep already and
the softirq can dig through it even further. To add insult to the
injury, this softirq can be interrupted by a new hardirq, maximizing
the chances for a stack overrun as reported in powerpc for example:
do_IRQ: stack overflow: 1920
CPU: 0 PID: 1602 Comm: qemu-system-ppc Not tainted 3.10.4-300.1.fc19.ppc64p7 #1
Call Trace:
[c0000000050a8740] .show_stack+0x130/0x200 (unreliable)
[c0000000050a8810] .dump_stack+0x28/0x3c
[c0000000050a8880] .do_IRQ+0x2b8/0x2c0
[c0000000050a8930] hardware_interrupt_common+0x154/0x180
--- Exception: 501 at .cp_start_xmit+0x3a4/0x820 [8139cp]
LR = .cp_start_xmit+0x390/0x820 [8139cp]
[c0000000050a8d40] .dev_hard_start_xmit+0x394/0x640
[c0000000050a8e00] .sch_direct_xmit+0x110/0x260
[c0000000050a8ea0] .dev_queue_xmit+0x260/0x630
[c0000000050a8f40] .br_dev_queue_push_xmit+0xc4/0x130 [bridge]
[c0000000050a8fc0] .br_dev_xmit+0x198/0x270 [bridge]
[c0000000050a9070] .dev_hard_start_xmit+0x394/0x640
[c0000000050a9130] .dev_queue_xmit+0x428/0x630
[c0000000050a91d0] .ip_finish_output+0x2a4/0x550
[c0000000050a9290] .ip_local_out+0x50/0x70
[c0000000050a9310] .ip_queue_xmit+0x148/0x420
[c0000000050a93b0] .tcp_transmit_skb+0x4e4/0xaf0
[c0000000050a94a0] .__tcp_ack_snd_check+0x7c/0xf0
[c0000000050a9520] .tcp_rcv_established+0x1e8/0x930
[c0000000050a95f0] .tcp_v4_do_rcv+0x21c/0x570
[c0000000050a96c0] .tcp_v4_rcv+0x734/0x930
[c0000000050a97a0] .ip_local_deliver_finish+0x184/0x360
[c0000000050a9840] .ip_rcv_finish+0x148/0x400
[c0000000050a98d0] .__netif_receive_skb_core+0x4f8/0xb00
[c0000000050a99d0] .netif_receive_skb+0x44/0x110
[c0000000050a9a70] .br_handle_frame_finish+0x2bc/0x3f0 [bridge]
[c0000000050a9b20] .br_nf_pre_routing_finish+0x2ac/0x420 [bridge]
[c0000000050a9bd0] .br_nf_pre_routing+0x4dc/0x7d0 [bridge]
[c0000000050a9c70] .nf_iterate+0x114/0x130
[c0000000050a9d30] .nf_hook_slow+0xb4/0x1e0
[c0000000050a9e00] .br_handle_frame+0x290/0x330 [bridge]
[c0000000050a9ea0] .__netif_receive_skb_core+0x34c/0xb00
[c0000000050a9fa0] .netif_receive_skb+0x44/0x110
[c0000000050aa040] .napi_gro_receive+0xe8/0x120
[c0000000050aa0c0] .cp_rx_poll+0x31c/0x590 [8139cp]
[c0000000050aa1d0] .net_rx_action+0x1dc/0x310
[c0000000050aa2b0] .__do_softirq+0x158/0x330
[c0000000050aa3b0] .irq_exit+0xc8/0x110
[c0000000050aa430] .do_IRQ+0xdc/0x2c0
[c0000000050aa4e0] hardware_interrupt_common+0x154/0x180
--- Exception: 501 at .bad_range+0x1c/0x110
LR = .get_page_from_freelist+0x908/0xbb0
[c0000000050aa7d0] .list_del+0x18/0x50 (unreliable)
[c0000000050aa850] .get_page_from_freelist+0x908/0xbb0
[c0000000050aa9e0] .__alloc_pages_nodemask+0x21c/0xae0
[c0000000050aaba0] .alloc_pages_vma+0xd0/0x210
[c0000000050aac60] .handle_pte_fault+0x814/0xb70
[c0000000050aad50] .__get_user_pages+0x1a4/0x640
[c0000000050aae60] .get_user_pages_fast+0xec/0x160
[c0000000050aaf10] .__gfn_to_pfn_memslot+0x3b0/0x430 [kvm]
[c0000000050aafd0] .kvmppc_gfn_to_pfn+0x64/0x130 [kvm]
[c0000000050ab070] .kvmppc_mmu_map_page+0x94/0x530 [kvm]
[c0000000050ab190] .kvmppc_handle_pagefault+0x174/0x610 [kvm]
[c0000000050ab270] .kvmppc_handle_exit_pr+0x464/0x9b0 [kvm]
[c0000000050ab320] kvm_start_lightweight+0x1ec/0x1fc [kvm]
[c0000000050ab4f0] .kvmppc_vcpu_run_pr+0x168/0x3b0 [kvm]
[c0000000050ab9c0] .kvmppc_vcpu_run+0xc8/0xf0 [kvm]
[c0000000050aba50] .kvm_arch_vcpu_ioctl_run+0x5c/0x1a0 [kvm]
[c0000000050abae0] .kvm_vcpu_ioctl+0x478/0x730 [kvm]
[c0000000050abc90] .do_vfs_ioctl+0x4ec/0x7c0
[c0000000050abd80] .SyS_ioctl+0xd4/0xf0
[c0000000050abe30] syscall_exit+0x0/0x98
Since this is a regression, this patch proposes a minimalistic
and low-risk solution by blindly forcing the hardirq exit processing of
softirqs on the softirq stack. This way we should reduce significantly
the opportunities for task stack overflow dug by softirqs.
Longer term solutions may involve extending the hardirq stack coverage to
irq_exit(), etc...
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8ac1c8d5deba65513b6a82c35e89e73996c8e0d6 upstream.
After commit 829199197a43 ("kernel/audit.c: avoid negative sleep
durations") audit emitters will block forever if userspace daemon cannot
handle backlog.
After the timeout the waiting loop turns into busy loop and runs until
daemon dies or returns back to work. This is a minimal patch for that
bug.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Richard Guy Briggs <rgb@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Chuck Anderson <chuck.anderson@oracle.com>
Cc: Dan Duval <dan.duval@oracle.com>
Cc: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jonghwan Choi <jhbird.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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|
invalid ones
commit 6c9a27f5da9609fca46cb2b183724531b48f71ad upstream.
There is a small race between copy_process() and cgroup_attach_task()
where child->se.parent,cfs_rq points to invalid (old) ones.
parent doing fork() | someone moving the parent to another cgroup
-------------------------------+---------------------------------------------
copy_process()
+ dup_task_struct()
-> parent->se is copied to child->se.
se.parent,cfs_rq of them point to old ones.
cgroup_attach_task()
+ cgroup_task_migrate()
-> parent->cgroup is updated.
+ cpu_cgroup_attach()
+ sched_move_task()
+ task_move_group_fair()
+- set_task_rq()
-> se.parent,cfs_rq of parent
are updated.
+ cgroup_fork()
-> parent->cgroup is copied to child->cgroup. (*1)
+ sched_fork()
+ task_fork_fair()
-> se.parent,cfs_rq of child are accessed
while they point to old ones. (*2)
In the worst case, this bug can lead to "use-after-free" and cause a panic,
because it's new cgroup's refcount that is incremented at (*1),
so the old cgroup(and related data) can be freed before (*2).
In fact, a panic caused by this bug was originally caught in RHEL6.4.
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff81051e3e>] sched_slice+0x6e/0xa0
[...]
Call Trace:
[<ffffffff81051f25>] place_entity+0x75/0xa0
[<ffffffff81056a3a>] task_fork_fair+0xaa/0x160
[<ffffffff81063c0b>] sched_fork+0x6b/0x140
[<ffffffff8106c3c2>] copy_process+0x5b2/0x1450
[<ffffffff81063b49>] ? wake_up_new_task+0xd9/0x130
[<ffffffff8106d2f4>] do_fork+0x94/0x460
[<ffffffff81072a9e>] ? sys_wait4+0xae/0x100
[<ffffffff81009598>] sys_clone+0x28/0x30
[<ffffffff8100b393>] stub_clone+0x13/0x20
[<ffffffff8100b072>] ? system_call_fastpath+0x16/0x1b
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/039601ceae06$733d3130$59b79390$@mxp.nes.nec.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5a8e01f8fa51f5cbce8f37acc050eb2319d12956 upstream.
scale_stime() silently assumes that stime < rtime, otherwise
when stime == rtime and both values are big enough (operations
on them do not fit in 32 bits), the resulting scaling stime can
be bigger than rtime. In consequence utime = rtime - stime
results in negative value.
User space visible symptoms of the bug are overflowed TIME
values on ps/top, for example:
$ ps aux | grep rcu
root 8 0.0 0.0 0 0 ? S 12:42 0:00 [rcuc/0]
root 9 0.0 0.0 0 0 ? S 12:42 0:00 [rcub/0]
root 10 62422329 0.0 0 0 ? R 12:42 21114581:37 [rcu_preempt]
root 11 0.1 0.0 0 0 ? S 12:42 0:02 [rcuop/0]
root 12 62422329 0.0 0 0 ? S 12:42 21114581:35 [rcuop/1]
root 10 62422329 0.0 0 0 ? R 12:42 21114581:37 [rcu_preempt]
or overflowed utime values read directly from /proc/$PID/stat
Reference:
https://lkml.org/lkml/2013/8/20/259
Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: stable@vger.kernel.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20130904131602.GC2564@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7bd36014460f793c19e7d6c94dab67b0afcfcb7f upstream.
Gerlando Falauto reported that when HRTICK is enabled, it is
possible to trigger system deadlocks. These were hard to
reproduce, as HRTICK has been broken in the past, but seemed
to be connected to the timekeeping_seq lock.
Since seqlock/seqcount's aren't supported w/ lockdep, I added
some extra spinlock based locking and triggered the following
lockdep output:
[ 15.849182] ntpd/4062 is trying to acquire lock:
[ 15.849765] (&(&pool->lock)->rlock){..-...}, at: [<ffffffff810aa9b5>] __queue_work+0x145/0x480
[ 15.850051]
[ 15.850051] but task is already holding lock:
[ 15.850051] (timekeeper_lock){-.-.-.}, at: [<ffffffff810df6df>] do_adjtimex+0x7f/0x100
<snip>
[ 15.850051] Chain exists of: &(&pool->lock)->rlock --> &p->pi_lock --> timekeeper_lock
[ 15.850051] Possible unsafe locking scenario:
[ 15.850051]
[ 15.850051] CPU0 CPU1
[ 15.850051] ---- ----
[ 15.850051] lock(timekeeper_lock);
[ 15.850051] lock(&p->pi_lock);
[ 15.850051] lock(timekeeper_lock);
[ 15.850051] lock(&(&pool->lock)->rlock);
[ 15.850051]
[ 15.850051] *** DEADLOCK ***
The deadlock was introduced by 06c017fdd4dc48451a ("timekeeping:
Hold timekeepering locks in do_adjtimex and hardpps") in 3.10
This patch avoids this deadlock, by moving the call to
schedule_delayed_work() outside of the timekeeper lock
critical section.
Reported-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Tested-by: Lin Ming <minggr@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: http://lkml.kernel.org/r/1378943457-27314-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e79f525e99b04390ca4d2366309545a836c03bf1 upstream.
Commit 8382fcac1b81 ("pidns: Outlaw thread creation after
unshare(CLONE_NEWPID)") nacks CLONE_VM if the forking process unshared
pid_ns, this obviously breaks vfork:
int main(void)
{
assert(unshare(CLONE_NEWUSER | CLONE_NEWPID) == 0);
assert(vfork() >= 0);
_exit(0);
return 0;
}
fails without this patch.
Change this check to use CLONE_SIGHAND instead. This also forbids
CLONE_THREAD automatically, and this is what the comment implies.
We could probably even drop CLONE_SIGHAND and use CLONE_THREAD, but it
would be safer to not do this. The current check denies CLONE_SIGHAND
implicitely and there is no reason to change this.
Eric said "CLONE_SIGHAND is fine. CLONE_THREAD would be even better.
Having shared signal handling between two different pid namespaces is
the case that we are fundamentally guarding against."
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Colin Walters <walters@redhat.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit a606488513543312805fab2b93070cefe6a3016c upstream.
Serge Hallyn <serge.hallyn@ubuntu.com> writes:
> Since commit af4b8a83add95ef40716401395b44a1b579965f4 it's been
> possible to get into a situation where a pidns reaper is
> <defunct>, reparented to host pid 1, but never reaped. How to
> reproduce this is documented at
>
> https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1168526
> (and see
> https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1168526/comments/13)
> In short, run repeated starts of a container whose init is
>
> Process.exit(0);
>
> sysrq-t when such a task is playing zombie shows:
>
> [ 131.132978] init x ffff88011fc14580 0 2084 2039 0x00000000
> [ 131.132978] ffff880116e89ea8 0000000000000002 ffff880116e89fd8 0000000000014580
> [ 131.132978] ffff880116e89fd8 0000000000014580 ffff8801172a0000 ffff8801172a0000
> [ 131.132978] ffff8801172a0630 ffff88011729fff0 ffff880116e14650 ffff88011729fff0
> [ 131.132978] Call Trace:
> [ 131.132978] [<ffffffff816f6159>] schedule+0x29/0x70
> [ 131.132978] [<ffffffff81064591>] do_exit+0x6e1/0xa40
> [ 131.132978] [<ffffffff81071eae>] ? signal_wake_up_state+0x1e/0x30
> [ 131.132978] [<ffffffff8106496f>] do_group_exit+0x3f/0xa0
> [ 131.132978] [<ffffffff810649e4>] SyS_exit_group+0x14/0x20
> [ 131.132978] [<ffffffff8170102f>] tracesys+0xe1/0xe6
>
> Further debugging showed that every time this happened, zap_pid_ns_processes()
> started with nr_hashed being 3, while we were expecting it to drop to 2.
> Any time it didn't happen, nr_hashed was 1 or 2. So the reaper was
> waiting for nr_hashed to become 2, but free_pid() only wakes the reaper
> if nr_hashed hits 1.
The issue is that when the task group leader of an init process exits
before other tasks of the init process when the init process finally
exits it will be a secondary task sleeping in zap_pid_ns_processes and
waiting to wake up when the number of hashed pids drops to two. This
case waits forever as free_pid only sends a wake up when the number of
hashed pids drops to 1.
To correct this the simple strategy of sending a possibly unncessary
wake up when the number of hashed pids drops to 2 is adopted.
Sending one extraneous wake up is relatively harmless, at worst we
waste a little cpu time in the rare case when a pid namespace
appropaches exiting.
We can detect the case when the pid namespace drops to just two pids
hashed race free in free_pid.
Dereferencing pid_ns->child_reaper with the pidmap_lock held is safe
without out the tasklist_lock because it is guaranteed that the
detach_pid will be called on the child_reaper before it is freed and
detach_pid calls __change_pid which calls free_pid which takes the
pidmap_lock. __change_pid only calls free_pid if this is the
last use of the pid. For a thread that is not the thread group leader
the threads pid will only ever have one user because a threads pid
is not allowed to be the pid of a process, of a process group or
a session. For a thread that is a thread group leader all of
the other threads of that process will be reaped before it is allowed
for the thread group leader to be reaped ensuring there will only
be one user of the threads pid as a process pid. Furthermore
because the thread is the init process of a pid namespace all of the
other processes in the pid namespace will have also been already freed
leading to the fact that the pid will not be used as a session pid or
a process group pid for any other running process.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Tested-by: Serge Hallyn <serge.hallyn@canonical.com>
Reported-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
commit 878b5a6efd38030c7a90895dc8346e8fb1e09b4c upstream.
Currently utask->depth is simply the number of allocated/pending
return_instance's in uprobe_task->return_instances list.
handle_trampoline() should decrement this counter every time we
handle/free an instance, but due to typo it does this only if
->chained == T. This means that in the likely case this counter
is never decremented and the probed task can't report more than
MAX_URETPROBE_DEPTH events.
Reported-by: Mikhail Kulemin <Mikhail.Kulemin@ru.ibm.com>
Reported-by: Hemant Kumar Shaw <hkshaw@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Cc: masami.hiramatsu.pt@hitachi.com
Cc: srikar@linux.vnet.ibm.com
Cc: systemtap@sourceware.org
Link: http://lkml.kernel.org/r/20130911154726.GA8093@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit b22ce2785d97423846206cceec4efee0c4afd980 upstream.
If !PREEMPT, a kworker running work items back to back can hog CPU.
This becomes dangerous when a self-requeueing work item which is
waiting for something to happen races against stop_machine. Such
self-requeueing work item would requeue itself indefinitely hogging
the kworker and CPU it's running on while stop_machine would wait for
that CPU to enter stop_machine while preventing anything else from
happening on all other CPUs. The two would deadlock.
Jamie Liu reports that this deadlock scenario exists around
scsi_requeue_run_queue() and libata port multiplier support, where one
port may exclude command processing from other ports. With the right
timing, scsi_requeue_run_queue() can end up requeueing itself trying
to execute an IO which is asked to be retried while another device has
an exclusive access, which in turn can't make forward progress due to
stop_machine.
Fix it by invoking cond_resched() after executing each work item.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jamie Liu <jamieliu@google.com>
References: http://thread.gmane.org/gmane.linux.kernel/1552567
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 84a78a6504f5c5394a8e558702e5b54131f01d14 upstream.
Correct an issue with /proc/timer_list reported by Holger.
When reading from the proc file with a sufficiently small buffer, 2k so
not really that small, there was one could get hung trying to read the
file a chunk at a time.
The timer_list_start function failed to account for the possibility that
the offset was adjusted outside the timer_list_next.
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Reported-by: Holger Hans Peter Freyther <holger@freyther.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Berke Durak <berke.durak@xiphos.com>
Cc: Jeff Layton <jlayton@redhat.com>
Tested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8c4f3c3fa9681dc549cd35419b259496082fef8b upstream.
There's been a nasty bug that would show up and not give much info.
The bug displayed the following warning:
WARNING: at kernel/trace/ftrace.c:1529 __ftrace_hash_rec_update+0x1e3/0x230()
Pid: 20903, comm: bash Tainted: G O 3.6.11+ #38405.trunk
Call Trace:
[<ffffffff8103e5ff>] warn_slowpath_common+0x7f/0xc0
[<ffffffff8103e65a>] warn_slowpath_null+0x1a/0x20
[<ffffffff810c2ee3>] __ftrace_hash_rec_update+0x1e3/0x230
[<ffffffff810c4f28>] ftrace_hash_move+0x28/0x1d0
[<ffffffff811401cc>] ? kfree+0x2c/0x110
[<ffffffff810c68ee>] ftrace_regex_release+0x8e/0x150
[<ffffffff81149f1e>] __fput+0xae/0x220
[<ffffffff8114a09e>] ____fput+0xe/0x10
[<ffffffff8105fa22>] task_work_run+0x72/0x90
[<ffffffff810028ec>] do_notify_resume+0x6c/0xc0
[<ffffffff8126596e>] ? trace_hardirqs_on_thunk+0x3a/0x3c
[<ffffffff815c0f88>] int_signal+0x12/0x17
---[ end trace 793179526ee09b2c ]---
It was finally narrowed down to unloading a module that was being traced.
It was actually more than that. When functions are being traced, there's
a table of all functions that have a ref count of the number of active
tracers attached to that function. When a function trace callback is
registered to a function, the function's record ref count is incremented.
When it is unregistered, the function's record ref count is decremented.
If an inconsistency is detected (ref count goes below zero) the above
warning is shown and the function tracing is permanently disabled until
reboot.
The ftrace callback ops holds a hash of functions that it filters on
(and/or filters off). If the hash is empty, the default means to filter
all functions (for the filter_hash) or to disable no functions (for the
notrace_hash).
When a module is unloaded, it frees the function records that represent
the module functions. These records exist on their own pages, that is
function records for one module will not exist on the same page as
function records for other modules or even the core kernel.
Now when a module unloads, the records that represents its functions are
freed. When the module is loaded again, the records are recreated with
a default ref count of zero (unless there's a callback that traces all
functions, then they will also be traced, and the ref count will be
incremented).
The problem is that if an ftrace callback hash includes functions of the
module being unloaded, those hash entries will not be removed. If the
module is reloaded in the same location, the hash entries still point
to the functions of the module but the module's ref counts do not reflect
that.
With the help of Steve and Joern, we found a reproducer:
Using uinput module and uinput_release function.
cd /sys/kernel/debug/tracing
modprobe uinput
echo uinput_release > set_ftrace_filter
echo function > current_tracer
rmmod uinput
modprobe uinput
# check /proc/modules to see if loaded in same addr, otherwise try again
echo nop > current_tracer
[BOOM]
The above loads the uinput module, which creates a table of functions that
can be traced within the module.
We add uinput_release to the filter_hash to trace just that function.
Enable function tracincg, which increments the ref count of the record
associated to uinput_release.
Remove uinput, which frees the records including the one that represents
uinput_release.
Load the uinput module again (and make sure it's at the same address).
This recreates the function records all with a ref count of zero,
including uinput_release.
Disable function tracing, which will decrement the ref count for uinput_release
which is now zero because of the module removal and reload, and we have
a mismatch (below zero ref count).
The solution is to check all currently tracing ftrace callbacks to see if any
are tracing any of the module's functions when a module is loaded (it already does
that with callbacks that trace all functions). If a callback happens to have
a module function being traced, it increments that records ref count and starts
tracing that function.
There may be a strange side effect with this, where tracing module functions
on unload and then reloading a new module may have that new module's functions
being traced. This may be something that confuses the user, but it's not
a big deal. Another approach is to disable all callback hashes on module unload,
but this leaves some ftrace callbacks that may not be registered, but can
still have hashes tracing the module's function where ftrace doesn't know about
it. That situation can cause the same bug. This solution solves that case too.
Another benefit of this solution, is it is possible to trace a module's
function on unload and load.
Link: http://lkml.kernel.org/r/20130705142629.GA325@redhat.com
Reported-by: Jörn Engel <joern@logfs.org>
Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Steve Hodgson <steve@purestorage.com>
Tested-by: Steve Hodgson <steve@purestorage.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit c6c2401d8bbaf9edc189b4c35a8cb2780b8b988e upstream.
Uprobes suffer the same problem that kprobes have. There's a race between
writing to the "enable" file and removing the probe. The probe checks for
it being in use and if it is not, goes about deleting the probe and the
event that represents it. But the problem with that is, after it checks
if it is in use it can be enabled, and the deletion of the event (access
to the probe) will fail, as it is in use. But the uprobe will still be
deleted. This is a problem as the event can reference the uprobe that
was deleted.
The fix is to remove the event first, and check to make sure the event
removal succeeds. Then it is safe to remove the probe.
When the event exists, either ftrace or perf can enable the probe and
prevent the event from being removed.
Link: http://lkml.kernel.org/r/20130704034038.991525256@goodmis.org
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 40c32592668b727cbfcf7b1c0567f581bd62a5e4 upstream.
When a probe is being removed, it cleans up the event files that correspond
to the probe. But there is a race between writing to one of these files
and deleting the probe. This is especially true for the "enable" file.
CPU 0 CPU 1
----- -----
fd = open("enable",O_WRONLY);
probes_open()
release_all_trace_probes()
unregister_trace_probe()
if (trace_probe_is_enabled(tp))
return -EBUSY
write(fd, "1", 1)
__ftrace_set_clr_event()
call->class->reg()
(kprobe_register)
enable_trace_probe(tp)
__unregister_trace_probe(tp);
list_del(&tp->list)
unregister_probe_event(tp) <-- fails!
free_trace_probe(tp)
write(fd, "0", 1)
__ftrace_set_clr_event()
call->class->unreg
(kprobe_register)
disable_trace_probe(tp) <-- BOOM!
A test program was written that used two threads to simulate the
above scenario adding a nanosleep() interval to change the timings
and after several thousand runs, it was able to trigger this bug
and crash:
BUG: unable to handle kernel paging request at 00000005000000f9
IP: [<ffffffff810dee70>] probes_open+0x3b/0xa7
PGD 7808a067 PUD 0
Oops: 0000 [#1] PREEMPT SMP
Dumping ftrace buffer:
---------------------------------
Modules linked in: ipt_MASQUERADE sunrpc ip6t_REJECT nf_conntrack_ipv6
CPU: 1 PID: 2070 Comm: test-kprobe-rem Not tainted 3.11.0-rc3-test+ #47
Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
task: ffff880077756440 ti: ffff880076e52000 task.ti: ffff880076e52000
RIP: 0010:[<ffffffff810dee70>] [<ffffffff810dee70>] probes_open+0x3b/0xa7
RSP: 0018:ffff880076e53c38 EFLAGS: 00010203
RAX: 0000000500000001 RBX: ffff88007844f440 RCX: 0000000000000003
RDX: 0000000000000003 RSI: 0000000000000003 RDI: ffff880076e52000
RBP: ffff880076e53c58 R08: ffff880076e53bd8 R09: 0000000000000000
R10: ffff880077756440 R11: 0000000000000006 R12: ffffffff810dee35
R13: ffff880079250418 R14: 0000000000000000 R15: ffff88007844f450
FS: 00007f87a276f700(0000) GS:ffff88007d480000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000005000000f9 CR3: 0000000077262000 CR4: 00000000000007e0
Stack:
ffff880076e53c58 ffffffff81219ea0 ffff88007844f440 ffffffff810dee35
ffff880076e53ca8 ffffffff81130f78 ffff8800772986c0 ffff8800796f93a0
ffffffff81d1b5d8 ffff880076e53e04 0000000000000000 ffff88007844f440
Call Trace:
[<ffffffff81219ea0>] ? security_file_open+0x2c/0x30
[<ffffffff810dee35>] ? unregister_trace_probe+0x4b/0x4b
[<ffffffff81130f78>] do_dentry_open+0x162/0x226
[<ffffffff81131186>] finish_open+0x46/0x54
[<ffffffff8113f30b>] do_last+0x7f6/0x996
[<ffffffff8113cc6f>] ? inode_permission+0x42/0x44
[<ffffffff8113f6dd>] path_openat+0x232/0x496
[<ffffffff8113fc30>] do_filp_open+0x3a/0x8a
[<ffffffff8114ab32>] ? __alloc_fd+0x168/0x17a
[<ffffffff81131f4e>] do_sys_open+0x70/0x102
[<ffffffff8108f06e>] ? trace_hardirqs_on_caller+0x160/0x197
[<ffffffff81131ffe>] SyS_open+0x1e/0x20
[<ffffffff81522742>] system_call_fastpath+0x16/0x1b
Code: e5 41 54 53 48 89 f3 48 83 ec 10 48 23 56 78 48 39 c2 75 6c 31 f6 48 c7
RIP [<ffffffff810dee70>] probes_open+0x3b/0xa7
RSP <ffff880076e53c38>
CR2: 00000005000000f9
---[ end trace 35f17d68fc569897 ]---
The unregister_trace_probe() must be done first, and if it fails it must
fail the removal of the kprobe.
Several changes have already been made by Oleg Nesterov and Masami Hiramatsu
to allow moving the unregister_probe_event() before the removal of
the probe and exit the function if it fails. This prevents the tp
structure from being used after it is freed.
Link: http://lkml.kernel.org/r/20130704034038.819592356@goodmis.org
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2816c551c796ec14620325b2c9ed75b9979d3125 upstream.
Change trace_remove_event_call(call) to return the error if this
call is active. This is what the callers assume but can't verify
outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c
need the additional changes, unregister_trace_probe() should abort
if trace_remove_event_call() fails.
The caller is going to free this call/file so we must ensure that
nobody can use them after trace_remove_event_call() succeeds.
debugfs should be fine after the previous changes and event_remove()
does TRACE_REG_UNREGISTER, but still there are 2 reasons why we need
the additional checks:
- There could be a perf_event(s) attached to this tp_event, so the
patch checks ->perf_refcount.
- TRACE_REG_UNREGISTER can be suppressed by FTRACE_EVENT_FL_SOFT_MODE,
so we simply check FTRACE_EVENT_FL_ENABLED protected by event_mutex.
Link: http://lkml.kernel.org/r/20130729175033.GB26284@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit bf682c3159c4d298d1126a56793ed3f5e80395f7 upstream.
Change remove_event_file_dir() to clear ->i_private for every
file we are going to remove.
We need to check file->dir != NULL because event_create_dir()
can fail. debugfs_remove_recursive(NULL) is fine but the patch
moves it under the same check anyway for readability.
spin_lock(d_lock) and "d_inode != NULL" check are not needed
afaics, but I do not understand this code enough.
tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete().
f_op->read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use ->i_private
under event_mutex.
Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.
Link: http://lkml.kernel.org/r/20130728183527.GB16723@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f6a84bdc75b5c11621dec58db73fe102cbaf40cc upstream.
Preparation for the next patch. Extract the common code from
remove_event_from_tracers() and __trace_remove_event_dirs()
into the new helper, remove_event_file_dir().
The patch looks more complicated than it actually is, it also
moves remove_subsystem() up to avoid the forward declaration.
Link: http://lkml.kernel.org/r/20130726172547.GA3629@redhat.com
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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