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* fork: make whole stack_canary randomJann Horn2017-10-141-1/+1
| | | | | | | | | | | | | | | | On machines with sizeof(unsigned long)==8, this ensures that the more significant 32 bits of stack_canary are random, too. stack_canary is defined as unsigned long, all the architectures with stack protector support already pick the stack_canary of init as a random unsigned long, and get_random_long() should be as fast as get_random_int(), so there seems to be no good reason against this. This should help if someone tries to guess a stack canary with brute force. (This change has been made in PaX already, with a different RNG.) Signed-off-by: Jann Horn <jann@thejh.net> Acked-by: Kees Cook <keescook@chromium.org>
* CHROMIUM: remove Android's cgroup generic permissions checksDmitry Torokhov2017-09-302-50/+3
| | | | | | | | | | | | | | | | | | | | The implementation is utterly broken, resulting in all processes being allows to move tasks between sets (as long as they have access to the "tasks" attribute), and upstream is heading towards checking only capability anyway, so let's get rid of this code. BUG=b:31790445,chromium:647994 TEST=Boot android container, examine logcat Change-Id: I2f780a5992c34e52a8f2d0b3557fc9d490da2779 Signed-off-by: Dmitry Torokhov <dtor@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/394967 Reviewed-by: Ricky Zhou <rickyz@chromium.org> Reviewed-by: John Stultz <john.stultz@linaro.org> (cherry picked from commit 6895149f8bf0719aa70487e285fa6a8ad3d2692d) Reviewed-on: https://chromium-review.googlesource.com/399858 Reviewed-by: Guenter Roeck <groeck@chromium.org> Signed-off-by: Mister Oyster <oysterized@gmail.com>
* misc: replace __FUNCTION__ by __function__Moyster2017-09-233-4/+4
| | | | | result of : git grep -l '__FUNCTION__' | xargs sed -i 's/__FUNCTION__/__func__/g'
* drivers: merged Android Binder from 4.9Lukas06102017-09-161-9/+0
| | | | | Change-Id: I857ef86b2d502293fb8c37398383dceaa21dd29f Signed-off-by: Mister Oyster <oysterized@gmail.com>
* lib: vsprintf: whitelist stack tracesDave Weinstein2017-09-141-1/+1
| | | | | | | | | Use the %pP functionality to explicitly allow kernel pointers to be logged for stack traces BUG: 30368199 Change-Id: I495915465565293e9e4da5aa28fbd1d14538d99b Signed-off-by: Dave Weinstein <olorin@google.com>
* perf/core: Fix group {cpu,task} validationMark Rutland2017-09-111-20/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 64aee2a965cf2954a038b5522f11d2cd2f0f8f3e upstream. Regardless of which events form a group, it does not make sense for the events to target different tasks and/or CPUs, as this leaves the group inconsistent and impossible to schedule. The core perf code assumes that these are consistent across (successfully intialised) groups. Core perf code only verifies this when moving SW events into a HW context. Thus, we can violate this requirement for pure SW groups and pure HW groups, unless the relevant PMU driver happens to perform this verification itself. These mismatched groups subsequently wreak havoc elsewhere. For example, we handle watchpoints as SW events, and reserve watchpoint HW on a per-CPU basis at pmu::event_init() time to ensure that any event that is initialised is guaranteed to have a slot at pmu::add() time. However, the core code only checks the group leader's cpu filter (via event_filter_match()), and can thus install follower events onto CPUs violating thier (mismatched) CPU filters, potentially installing them into a CPU without sufficient reserved slots. This can be triggered with the below test case, resulting in warnings from arch backends. #define _GNU_SOURCE #include <linux/hw_breakpoint.h> #include <linux/perf_event.h> #include <sched.h> #include <stdio.h> #include <sys/prctl.h> #include <sys/syscall.h> #include <unistd.h> static int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu, int group_fd, unsigned long flags) { return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags); } char watched_char; struct perf_event_attr wp_attr = { .type = PERF_TYPE_BREAKPOINT, .bp_type = HW_BREAKPOINT_RW, .bp_addr = (unsigned long)&watched_char, .bp_len = 1, .size = sizeof(wp_attr), }; int main(int argc, char *argv[]) { int leader, ret; cpu_set_t cpus; /* * Force use of CPU0 to ensure our CPU0-bound events get scheduled. */ CPU_ZERO(&cpus); CPU_SET(0, &cpus); ret = sched_setaffinity(0, sizeof(cpus), &cpus); if (ret) { printf("Unable to set cpu affinity\n"); return 1; } /* open leader event, bound to this task, CPU0 only */ leader = perf_event_open(&wp_attr, 0, 0, -1, 0); if (leader < 0) { printf("Couldn't open leader: %d\n", leader); return 1; } /* * Open a follower event that is bound to the same task, but a * different CPU. This means that the group should never be possible to * schedule. */ ret = perf_event_open(&wp_attr, 0, 1, leader, 0); if (ret < 0) { printf("Couldn't open mismatched follower: %d\n", ret); return 1; } else { printf("Opened leader/follower with mismastched CPUs\n"); } /* * Open as many independent events as we can, all bound to the same * task, CPU0 only. */ do { ret = perf_event_open(&wp_attr, 0, 0, -1, 0); } while (ret >= 0); /* * Force enable/disble all events to trigger the erronoeous * installation of the follower event. */ printf("Opened all events. Toggling..\n"); for (;;) { prctl(PR_TASK_PERF_EVENTS_DISABLE, 0, 0, 0, 0); prctl(PR_TASK_PERF_EVENTS_ENABLE, 0, 0, 0, 0); } return 0; } Fix this by validating this requirement regardless of whether we're moving events. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Zhou Chengming <zhouchengming1@huawei.com> Link: http://lkml.kernel.org/r/1498142498-15758-1-git-send-email-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
* hrtimer: Prevent enqueue of hrtimer on dead CPUMichael Bohan2017-09-111-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Date Wed, 10 Apr 2013 14:07:48 -0700 When switching the hrtimer cpu_base, we briefly allow for preemption to become enabled by unlocking the cpu_base lock. During this time, the CPU corresponding to the new cpu_base that was selected may in fact go offline. In this scenario, the hrtimer is enqueued to a CPU that's not online, and therefore it never fires. As an example, consider this example: CPU #0 CPU #1 ---- ---- ... hrtimer_start() lock_hrtimer_base() switch_hrtimer_base() cpu = hrtimer_get_target() -> 1 spin_unlock(&cpu_base->lock) <migrate thread to CPU #0> <offline> spin_lock(&new_base->lock) this_cpu = 0 cpu != this_cpu enqueue_hrtimer(cpu_base #1) To prevent this scenario, verify that the CPU corresponding to the new cpu_base is indeed online before selecting it in hrtimer_switch_base(). If it's not online, fallback to using the base of the current CPU. Change-Id: I3aaf5b806a25d5a8b96d6ccea7a042d2718091f7 Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
* hrtimer: Consider preemption when migrating hrtimer cpu_basesMichael Bohan2017-09-111-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Date Wed, 10 Apr 2013 14:07:47 -0700 When switching to a new cpu_base in switch_hrtimer_base(), we briefly enable preemption by unlocking the cpu_base lock in two places. During this interval it's possible for the running thread to be swapped to a different CPU. Consider the following example: CPU #0 CPU #1 ---- ---- hrtimer_start() ... lock_hrtimer_base() switch_hrtimer_base() this_cpu = 0; target_cpu_base = 0; raw_spin_unlock(&cpu_base->lock) <migrate to CPU 1> ... this_cpu == 0 cpu == this_cpu timer->base = CPU #0 timer->base != LOCAL_CPU Since the cached this_cpu is no longer accurate, we'll skip the hrtimer_check_target() check. Once we eventually go to program the hardware, we'll decide not to do so since it knows the real CPU that we're running on is not the same as the chosen base. As a consequence, we may end up missing the hrtimer's deadline. Fix this by updating the local CPU number each time we retake a cpu_base lock in switch_hrtimer_base(). Another possibility is to disable preemption across the whole of switch_hrtimer_base. This looks suboptimal since preemption would be disabled while waiting for lock(s). Change-Id: I46be5cf3069f8e6683ad8fff0841949bdb801684 Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
* sched: Micro-optimize the smart wake-affine logicPeter Zijlstra2017-09-113-2/+8
| | | | | | | | | | | | | | | | | | | | | Smart wake-affine is using node-size as the factor currently, but the overhead of the mask operation is high. Thus, this patch introduce the 'sd_llc_size' percpu variable, which will record the highest cache-share domain size, and make it to be the new factor, in order to reduce the overhead and make it more reasonable. Tested-by: Davidlohr Bueso <davidlohr.bueso@hp.com> Tested-by: Michael Wang <wangyun@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michael Wang <wangyun@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Link: http://lkml.kernel.org/r/51D5008E.6030102@linux.vnet.ibm.com [ Tidied up the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Change-Id: I8fb3ceac1e6944db078932172c99d544a4e304e4 Signed-off-by: Paul Reioux <reioux@gmail.com>
* sched: Implement smarter wake-affine logicMichael Wang2017-09-111-0/+47
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The wake-affine scheduler feature is currently always trying to pull the wakee close to the waker. In theory this should be beneficial if the waker's CPU caches hot data for the wakee, and it's also beneficial in the extreme ping-pong high context switch rate case. Testing shows it can benefit hackbench up to 15%. However, the feature is somewhat blind, from which some workloads such as pgbench suffer. It's also time-consuming algorithmically. Testing shows it can damage pgbench up to 50% - far more than the benefit it brings in the best case. So wake-affine should be smarter and it should realize when to stop its thankless effort at trying to find a suitable CPU to wake on. This patch introduces 'wakee_flips', which will be increased each time the task flips (switches) its wakee target. So a high 'wakee_flips' value means the task has more than one wakee, and the bigger the number, the higher the wakeup frequency. Now when making the decision on whether to pull or not, pay attention to the wakee with a high 'wakee_flips', pulling such a task may benefit the wakee. Also imply that the waker will face cruel competition later, it could be very cruel or very fast depends on the story behind 'wakee_flips', waker therefore suffers. Furthermore, if waker also has a high 'wakee_flips', that implies that multiple tasks rely on it, then waker's higher latency will damage all of them, so pulling wakee seems to be a bad deal. Thus, when 'waker->wakee_flips / wakee->wakee_flips' becomes higher and higher, the cost of pulling seems to be worse and worse. The patch therefore helps the wake-affine feature to stop its pulling work when: wakee->wakee_flips > factor && waker->wakee_flips > (factor * wakee->wakee_flips) The 'factor' here is the number of CPUs in the current CPU's NUMA node, so a bigger node will lead to more pulling since the trial becomes more severe. After applying the patch, pgbench shows up to 40% improvements and no regressions. Tested with 12 cpu x86 server and tip 3.10.0-rc7. The percentages in the final column highlight the areas with the biggest wins, all other areas improved as well: pgbench base smart | db_size | clients | tps | | tps | +---------+---------+-------+ +-------+ | 22 MB | 1 | 10598 | | 10796 | | 22 MB | 2 | 21257 | | 21336 | | 22 MB | 4 | 41386 | | 41622 | | 22 MB | 8 | 51253 | | 57932 | | 22 MB | 12 | 48570 | | 54000 | | 22 MB | 16 | 46748 | | 55982 | +19.75% | 22 MB | 24 | 44346 | | 55847 | +25.93% | 22 MB | 32 | 43460 | | 54614 | +25.66% | 7484 MB | 1 | 8951 | | 9193 | | 7484 MB | 2 | 19233 | | 19240 | | 7484 MB | 4 | 37239 | | 37302 | | 7484 MB | 8 | 46087 | | 50018 | | 7484 MB | 12 | 42054 | | 48763 | | 7484 MB | 16 | 40765 | | 51633 | +26.66% | 7484 MB | 24 | 37651 | | 52377 | +39.11% | 7484 MB | 32 | 37056 | | 51108 | +37.92% | 15 GB | 1 | 8845 | | 9104 | | 15 GB | 2 | 19094 | | 19162 | | 15 GB | 4 | 36979 | | 36983 | | 15 GB | 8 | 46087 | | 49977 | | 15 GB | 12 | 41901 | | 48591 | | 15 GB | 16 | 40147 | | 50651 | +26.16% | 15 GB | 24 | 37250 | | 52365 | +40.58% | 15 GB | 32 | 36470 | | 50015 | +37.14% Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/51D50057.9000809@linux.vnet.ibm.com [ Improved the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Change-Id: I70018a00435ea795121b70a576d74bbbd00b7464 Signed-off-by: Paul Reioux <reioux@gmail.com>
* sched: reinitialize rq->next_balance when a CPU is hot-addedPaul Walmsley2017-09-111-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reinitialize rq->next_balance when a CPU is hot-added. Otherwise, scheduler domain rebalancing may be skipped if rq->next_balance was set to a future time when the CPU was last active, and the newly-re-added CPU is in idle_balance(). As a result, the newly-re-added CPU will remain idle with no tasks scheduled until the softlockup watchdog runs - potentially 4 seconds later. This can waste energy and reduce performance. This behavior can be observed in some SoC kernels, which use CPU hotplug to dynamically remove and add CPUs in response to load. In one case that triggered this behavior, 0. the system started with all cores enabled, running multi-threaded CPU-bound code; 1. the system entered some single-threaded code; 2. a CPU went idle and was hot-removed; 3. the system started executing a multi-threaded CPU-bound task; 4. the CPU from event 2 was re-added, to respond to the load. The time interval between events 2 and 4 was approximately 300 milliseconds. Of course, ideally CPU hotplug would not be used in this manner, but this patch does appear to fix a real bug. Nvidia folks: this patch is submitted as at least a partial fix for bug 1243368 ("[sched] Load-balancing not happening correctly after cores brought online") Change-Id: Iabac21e110402bb581b7db40c42babc951d378d0 Signed-off-by: Paul Walmsley <pwalmsley@nvidia.com> Cc: Peter Boonstoppel <pboonstoppel@nvidia.com> Reviewed-on: http://git-master/r/208927 Reviewed-by: Automatic_Commit_Validation_User Reviewed-by: Peter Zu <pzu@nvidia.com> Reviewed-by: Peter Boonstoppel <pboonstoppel@nvidia.com> GVS: Gerrit_Virtual_Submit Tested-by: Peter Zu <pzu@nvidia.com> Reviewed-by: Yu-Huan Hsu <yhsu@nvidia.com> Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
* PM / suspend: Remove unnecessary !!Viresh Kumar2017-09-111-1/+1
| | | | | | | | | | Double ! or !! are normally required to get 0 or 1 out of a expression. A comparision always returns 0 or 1 and hence there is no need to apply double ! over it again. Change-Id: Ia705389240381dd5cb04b81566021ea29af6b1d0 Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
* audit: Fix sleep in atomicJan Kara2017-08-311-2/+14
| | | | | | | | | | | | Audit tree code was happily adding new notification marks while holding spinlocks. Since fsnotify_add_mark() acquires group->mark_mutex this can lead to sleeping while holding a spinlock, deadlocks due to lock inversion, and probably other fun. Fix the problem by acquiring group->mark_mutex earlier. CC: Paul Moore <paul@paul-moore.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Paul Moore <paul@paul-moore.com>
* cputime: Fix jiffies based cputime assumption on steal accountingFrederic Weisbecker2017-08-311-5/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The steal guest time accounting code assumes that cputime_t is based on jiffies. So when CONFIG_NO_HZ_FULL=y, which implies that cputime_t is based on nsecs, steal_account_process_tick() passes the delta in jiffies to account_steal_time() which then accounts it as if it's a value in nsecs. As a result, accounting 1 second of steal time (with HZ=100 that would be 100 jiffies) is spuriously accounted as 100 nsecs. As such /proc/stat may report 0 values of steal time even when two guests have run concurrently for a few seconds on the same host and same CPU. In order to fix this, lets convert the nsecs based steal delta to cputime instead of jiffies by using the right conversion API. Given that the steal time is stored in cputime_t and this type can have a smaller granularity than nsecs, we only account the rounded converted value and leave the remaining nsecs for the next deltas. Reported-by: Huiqingding <huding@redhat.com> Reported-by: Marcelo Tosatti <mtosatti@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* BACKPORT: FROMLIST: pids: make task_tgid_nr_ns() safeOleg Nesterov2017-08-311-7/+4
| | | | | | | | | | | | | | | | | | | | | | This was reported many times, and this was even mentioned in commit 52ee2dfdd4f5 "pids: refactor vnr/nr_ns helpers to make them safe" but somehow nobody bothered to fix the obvious problem: task_tgid_nr_ns() is not safe because task->group_leader points to nowhere after the exiting task passes exit_notify(), rcu_read_lock() can not help. We really need to change __unhash_process() to nullify group_leader, parent, and real_parent, but this needs some cleanups. Until then we can turn task_tgid_nr_ns() into another user of __task_pid_nr_ns() and fix the problem. Reported-by: Troy Kensinger <tkensinger@google.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> (url: https://patchwork.kernel.org/patch/9913055/) Bug: 31495866 Change-Id: I5e67b02a77e805f71fa3a787249f13c1310f02e2
* sched/loadavg: Avoid loadavg spikes caused by delayed NO_HZ accountingMatt Fleming2017-08-311-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we crossed a sample window while in NO_HZ we will add LOAD_FREQ to the pending sample window time on exit, setting the next update not one window into the future, but two. This situation on exiting NO_HZ is described by: this_rq->calc_load_update < jiffies < calc_load_update In this scenario, what we should be doing is: this_rq->calc_load_update = calc_load_update [ next window ] But what we actually do is: this_rq->calc_load_update = calc_load_update + LOAD_FREQ [ next+1 window ] This has the effect of delaying load average updates for potentially up to ~9seconds. This can result in huge spikes in the load average values due to per-cpu uninterruptible task counts being out of sync when accumulated across all CPUs. It's safe to update the per-cpu active count if we wake between sample windows because any load that we left in 'calc_load_idle' will have been zero'd when the idle load was folded in calc_global_load(). This issue is easy to reproduce before, commit 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") just by forking short-lived process pipelines built from ps(1) and grep(1) in a loop. I'm unable to reproduce the spikes after that commit, but the bug still seems to be present from code review. Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Guittot <vincent.guittot@linaro.org> Fixes: commit 5167e8d ("sched/nohz: Rewrite and fix load-avg computation -- again") Link: http://lkml.kernel.org/r/20170217120731.11868-2-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org> [@nathanchance: Adjust for 3.10] Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
* sched/topology: Fix overlapping sched_group_maskPeter Zijlstra2017-08-311-1/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 73bb059f9b8a00c5e1bf2f7ca83138c05d05e600 upstream. The point of sched_group_mask is to select those CPUs from sched_group_cpus that can actually arrive at this balance domain. The current code gets it wrong, as can be readily demonstrated with a topology like: node 0 1 2 3 0: 10 20 30 20 1: 20 10 20 30 2: 30 20 10 20 3: 20 30 20 10 Where (for example) domain 1 on CPU1 ends up with a mask that includes CPU0: [] CPU1 attaching sched-domain: [] domain 0: span 0-2 level NUMA [] groups: 1 (mask: 1), 2, 0 [] domain 1: span 0-3 level NUMA [] groups: 0-2 (mask: 0-2) (cpu_capacity: 3072), 0,2-3 (cpu_capacity: 3072) This causes sched_balance_cpu() to compute the wrong CPU and consequently should_we_balance() will terminate early resulting in missed load-balance opportunities. The fixed topology looks like: [] CPU1 attaching sched-domain: [] domain 0: span 0-2 level NUMA [] groups: 1 (mask: 1), 2, 0 [] domain 1: span 0-3 level NUMA [] groups: 0-2 (mask: 1) (cpu_capacity: 3072), 0,2-3 (cpu_capacity: 3072) (note: this relies on OVERLAP domains to always have children, this is true because the regular topology domains are still here -- this is before degenerate trimming) Debugged-by: Lauro Ramos Venancio <lvenanci@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Fixes: e3589f6c81e4 ("sched: Allow for overlapping sched_domain spans") Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sched/topology: Optimize build_group_mask()Lauro Ramos Venancio2017-08-311-2/+2
| | | | | | | | | | | | | | | | | | | | commit f32d782e31bf079f600dcec126ed117b0577e85c upstream. The group mask is always used in intersection with the group CPUs. So, when building the group mask, we don't have to care about CPUs that are not part of the group. Signed-off-by: Lauro Ramos Venancio <lvenanci@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: lwang@redhat.com Cc: riel@redhat.com Link: http://lkml.kernel.org/r/1492717903-5195-2-git-send-email-lvenanci@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* alarmtimer: don't rate limit one-shot timersGreg Hackmann2017-08-311-1/+2
| | | | | | | | | | | | | | | Commit ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") sets a minimum bound on the alarm timer interval. This minimum bound shouldn't be applied if the interval is 0. Otherwise, one-shot timers will be converted into periodic ones. Fixes: ff86bf0c65f1 ("alarmtimer: Rate limit periodic intervals") Reported-by: Ben Fennema <fennema@google.com> Signed-off-by: Greg Hackmann <ghackmann@google.com> Cc: stable@vger.kernel.org Cc: John Stultz <john.stultz@linaro.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* alarmtimer: Rate limit periodic intervalsThomas Gleixner2017-08-311-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit ff86bf0c65f14346bf2440534f9ba5ac232c39a0 upstream. The alarmtimer code has another source of potentially rearming itself too fast. Interval timers with a very samll interval have a similar CPU hog effect as the previously fixed overflow issue. The reason is that alarmtimers do not implement the normal protection against this kind of problem which the other posix timer use: timer expires -> queue signal -> deliver signal -> rearm timer This scheme brings the rearming under scheduler control and prevents permanently firing timers which hog the CPU. Bringing this scheme to the alarm timer code is a major overhaul because it lacks all the necessary mechanisms completely. So for a quick fix limit the interval to one jiffie. This is not problematic in practice as alarmtimers are usually backed by an RTC for suspend which have 1 second resolution. It could be therefor argued that the resolution of this clock should be set to 1 second in general, but that's outside the scope of this fix. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kostya Serebryany <kcc@google.com> Cc: syzkaller <syzkaller@googlegroups.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Dmitry Vyukov <dvyukov@google.com> Link: http://lkml.kernel.org/r/20170530211655.896767100@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Revert "proc: smaps: Allow smaps access for CAP_SYS_RESOURCE"Daniel Mentz2017-07-111-2/+1
| | | | | | | | | | | | | | | This reverts commit d590b5b6953304edb000de90335a3b4838b2482c. This fixes CVE-2017-0710. SELinux allows more fine grained control: We grant processes that need access to smaps CAP_SYS_PTRACE but prohibit them from using ptrace attach(). Bug: 34951864 Bug: 36468447 Change-Id: I081033cf8fd7058b41cb464200b544e24651372d Signed-off-by: Daniel Mentz <danielmentz@google.com>
* uksm: remove Mtk aksm & uksm (because its fugly)Mister Oyster2017-07-041-2/+2
| | | | | | | | | | | | | | | | Revert "KSM: mediatek: implement Adaptive KSM" Revert "mm: uksm: fix maybe-uninitialized warning" Revert "UKSM: Add Governors for Higher CPU usage (HighCPU) for more merging, and low cpu usage (Battery) for less battery drain" Revert "uksm: use deferrable timer" Revert "mm: limit UKSM sleep time instead of failing" Revert "uksm: Fix warning" Revert "uksm: clean up and remove some (no)inlines" Revert "uksm: modify ema logic and tidy up" Revert "uksm: enhancements and cleanups" Revert "uksm: squashed fixups" Revert "UKSM: cast variable as const" Revert "UKSM: remove U64_MAX definition" Revert "add uksm 0.1.2.3 for v3.10 .ge.46.patch"
* printk: use rcuidle console tracepointSergey Senozhatsky2017-07-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit fc98c3c8c9dcafd67adcce69e6ce3191d5306c9c upstream. Use rcuidle console tracepoint because, apparently, it may be issued from an idle CPU: hw-breakpoint: Failed to enable monitor mode on CPU 0. hw-breakpoint: CPU 0 failed to disable vector catch =============================== [ ERR: suspicious RCU usage. ] 4.10.0-rc8-next-20170215+ #119 Not tainted ------------------------------- ./include/trace/events/printk.h:32 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 2, debug_locks = 0 RCU used illegally from extended quiescent state! 2 locks held by swapper/0/0: #0: (cpu_pm_notifier_lock){......}, at: [<c0237e2c>] cpu_pm_exit+0x10/0x54 #1: (console_lock){+.+.+.}, at: [<c01ab350>] vprintk_emit+0x264/0x474 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.10.0-rc8-next-20170215+ #119 Hardware name: Generic OMAP4 (Flattened Device Tree) console_unlock vprintk_emit vprintk_default printk reset_ctrl_regs dbg_cpu_pm_notify notifier_call_chain cpu_pm_exit omap_enter_idle_coupled cpuidle_enter_state cpuidle_enter_state_coupled do_idle cpu_startup_entry start_kernel This RCU warning, however, is suppressed by lockdep_off() in printk(). lockdep_off() increments the ->lockdep_recursion counter and thus disables RCU_LOCKDEP_WARN() and debug_lockdep_rcu_enabled(), which want lockdep to be enabled "current->lockdep_recursion == 0". Link: http://lkml.kernel.org/r/20170217015932.11898-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reported-by: Tony Lindgren <tony@atomide.com> Tested-by: Tony Lindgren <tony@atomide.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Lindgren <tony@atomide.com> Cc: Russell King <rmk@armlinux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> [wt: changes are in kernel/printk.c in 3.10] Signed-off-by: Willy Tarreau <w@1wt.eu>
* padata: avoid race in reorderingJason A. Donenfeld2017-07-041-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit de5540d088fe97ad583cc7d396586437b32149a5 upstream. Under extremely heavy uses of padata, crashes occur, and with list debugging turned on, this happens instead: [87487.298728] WARNING: CPU: 1 PID: 882 at lib/list_debug.c:33 __list_add+0xae/0x130 [87487.301868] list_add corruption. prev->next should be next (ffffb17abfc043d0), but was ffff8dba70872c80. (prev=ffff8dba70872b00). [87487.339011] [<ffffffff9a53d075>] dump_stack+0x68/0xa3 [87487.342198] [<ffffffff99e119a1>] ? console_unlock+0x281/0x6d0 [87487.345364] [<ffffffff99d6b91f>] __warn+0xff/0x140 [87487.348513] [<ffffffff99d6b9aa>] warn_slowpath_fmt+0x4a/0x50 [87487.351659] [<ffffffff9a58b5de>] __list_add+0xae/0x130 [87487.354772] [<ffffffff9add5094>] ? _raw_spin_lock+0x64/0x70 [87487.357915] [<ffffffff99eefd66>] padata_reorder+0x1e6/0x420 [87487.361084] [<ffffffff99ef0055>] padata_do_serial+0xa5/0x120 padata_reorder calls list_add_tail with the list to which its adding locked, which seems correct: spin_lock(&squeue->serial.lock); list_add_tail(&padata->list, &squeue->serial.list); spin_unlock(&squeue->serial.lock); This therefore leaves only place where such inconsistency could occur: if padata->list is added at the same time on two different threads. This pdata pointer comes from the function call to padata_get_next(pd), which has in it the following block: next_queue = per_cpu_ptr(pd->pqueue, cpu); padata = NULL; reorder = &next_queue->reorder; if (!list_empty(&reorder->list)) { padata = list_entry(reorder->list.next, struct padata_priv, list); spin_lock(&reorder->lock); list_del_init(&padata->list); atomic_dec(&pd->reorder_objects); spin_unlock(&reorder->lock); pd->processed++; goto out; } out: return padata; I strongly suspect that the problem here is that two threads can race on reorder list. Even though the deletion is locked, call to list_entry is not locked, which means it's feasible that two threads pick up the same padata object and subsequently call list_add_tail on them at the same time. The fix is thus be hoist that lock outside of that block. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Acked-by: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Willy Tarreau <w@1wt.eu>
* futex: Add missing error handling to FUTEX_REQUEUE_PIPeter Zijlstra2017-07-041-0/+2
| | | | | | | | | | | | | | | | | | | | | | commit 9bbb25afeb182502ca4f2c4f3f88af0681b34cae upstream. Thomas spotted that fixup_pi_state_owner() can return errors and we fail to unlock the rt_mutex in that case. Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Darren Hart <dvhart@linux.intel.com> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: dvhart@infradead.org Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170304093558.867401760@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Willy Tarreau <w@1wt.eu>
* futex: Fix potential use-after-free in FUTEX_REQUEUE_PIPeter Zijlstra2017-07-041-9/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c236c8e95a3d395b0494e7108f0d41cf36ec107c upstream. While working on the futex code, I stumbled over this potential use-after-free scenario. Dmitry triggered it later with syzkaller. pi_mutex is a pointer into pi_state, which we drop the reference on in unqueue_me_pi(). So any access to that pointer after that is bad. Since other sites already do rt_mutex_unlock() with hb->lock held, see for example futex_lock_pi(), simply move the unlock before unqueue_me_pi(). Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Darren Hart <dvhart@linux.intel.com> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: dvhart@infradead.org Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170304093558.801744246@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Willy Tarreau <w@1wt.eu>
* futex: Move futex_init() to core_initcallYang Yang2017-07-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 25f71d1c3e98ef0e52371746220d66458eac75bc upstream. The UEVENT user mode helper is enabled before the initcalls are executed and is available when the root filesystem has been mounted. The user mode helper is triggered by device init calls and the executable might use the futex syscall. futex_init() is marked __initcall which maps to device_initcall, but there is no guarantee that futex_init() is invoked _before_ the first device init call which triggers the UEVENT user mode helper. If the user mode helper uses the futex syscall before futex_init() then the syscall crashes with a NULL pointer dereference because the futex subsystem has not been initialized yet. Move futex_init() to core_initcall so futexes are initialized before the root filesystem is mounted and the usermode helper becomes available. [ tglx: Rewrote changelog ] Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Cc: jiang.biao2@zte.com.cn Cc: jiang.zhengxiong@zte.com.cn Cc: zhong.weidong@zte.com.cn Cc: deng.huali@zte.com.cn Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1483085875-6130-1-git-send-email-yang.yang29@zte.com.cn Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Willy Tarreau <w@1wt.eu>
* sched/debug: Don't dump sched debug info in SysRq-WRabin Vincent2017-07-041-1/+2
| | | | | | | | | | | | | | | | | | | commit fb90a6e93c0684ab2629a42462400603aa829b9c upstream. sysrq_sched_debug_show() can dump a lot of information. Don't print out all that if we're just trying to get a list of blocked tasks (SysRq-W). The information is still accessible with SysRq-T. Signed-off-by: Rabin Vincent <rabinv@axis.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1459777322-30902-1-git-send-email-rabin.vincent@axis.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Nikolay Borisov <n.borisov.lkml@gmail.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Willy Tarreau <w@1wt.eu>
* sysctl: fix proc_doulongvec_ms_jiffies_minmax()Eric Dumazet2017-07-041-0/+1
| | | | | | | | | | | | | | | commit ff9f8a7cf935468a94d9927c68b00daae701667e upstream. We perform the conversion between kernel jiffies and ms only when exporting kernel value to user space. We need to do the opposite operation when value is written by user. Only matters when HZ != 1000 Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
* tick/broadcast: Prevent NULL pointer dereferenceThomas Gleixner2017-07-041-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | commit c1a9eeb938b5433947e5ea22f89baff3182e7075 upstream. When a disfunctional timer, e.g. dummy timer, is installed, the tick core tries to setup the broadcast timer. If no broadcast device is installed, the kernel crashes with a NULL pointer dereference in tick_broadcast_setup_oneshot() because the function has no sanity check. Reported-by: Mason <slash.tmp@free.fr> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> Cc: Richard Cochran <rcochran@linutronix.de> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org>, Cc: Sebastian Frias <sf84@laposte.net> Cc: Thibaud Cornic <thibaud_cornic@sigmadesigns.com> Cc: Robin Murphy <robin.murphy@arm.com> Link: http://lkml.kernel.org/r/1147ef90-7877-e4d2-bb2b-5c4fa8d3144b@free.fr Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Willy Tarreau <w@1wt.eu>
* ring-buffer: Have ring_buffer_iter_empty() return true when emptySteven Rostedt (VMware)2017-06-171-2/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 78f7a45dac2a2d2002f98a3a95f7979867868d73 upstream. I noticed that reading the snapshot file when it is empty no longer gives a status. It suppose to show the status of the snapshot buffer as well as how to allocate and use it. For example: ># cat snapshot # tracer: nop # # # * Snapshot is allocated * # # Snapshot commands: # echo 0 > snapshot : Clears and frees snapshot buffer # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated. # Takes a snapshot of the main buffer. # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free) # (Doesn't have to be '2' works with any number that # is not a '0' or '1') But instead it just showed an empty buffer: ># cat snapshot # tracer: nop # # entries-in-buffer/entries-written: 0/0 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | What happened was that it was using the ring_buffer_iter_empty() function to see if it was empty, and if it was, it showed the status. But that function was returning false when it was empty. The reason was that the iter header page was on the reader page, and the reader page was empty, but so was the buffer itself. The check only tested to see if the iter was on the commit page, but the commit page was no longer pointing to the reader page, but as all pages were empty, the buffer is also. Fixes: 651e22f2701b ("ring-buffer: Always reset iterator to reader page") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
* tracing: Allocate the snapshot buffer before enabling probeSteven Rostedt (VMware)2017-06-171-3/+5
| | | | | | | | | | | | | | | | | commit df62db5be2e5f070ecd1a5ece5945b590ee112e0 upstream. Currently the snapshot trigger enables the probe and then allocates the snapshot. If the probe triggers before the allocation, it could cause the snapshot to fail and turn tracing off. It's best to allocate the snapshot buffer first, and then enable the trigger. If something goes wrong in the enabling of the trigger, the snapshot buffer is still allocated, but it can also be freed by the user by writting zero into the snapshot buffer file. Also add a check of the return status of alloc_snapshot(). Fixes: 77fd5c15e3 ("tracing: Add snapshot trigger to function probes") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
* ring-buffer: Fix return value check in test_ringbuffer()Wei Yongjun2017-06-171-4/+4
| | | | | | | | | | | | | | | commit 62277de758b155dc04b78f195a1cb5208c37b2df upstream. In case of error, the function kthread_run() returns ERR_PTR() and never returns NULL. The NULL test in the return value check should be replaced with IS_ERR(). Link: http://lkml.kernel.org/r/1466184839-14927-1-git-send-email-weiyj_lk@163.com Fixes: 6c43e554a ("ring-buffer: Add ring buffer startup selftest") Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
* ptrace: fix PTRACE_LISTEN race corrupting task->statebsegall@google.com2017-06-171-4/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 5402e97af667e35e54177af8f6575518bf251d51 upstream. In PT_SEIZED + LISTEN mode STOP/CONT signals cause a wakeup against __TASK_TRACED. If this races with the ptrace_unfreeze_traced at the end of a PTRACE_LISTEN, this can wake the task /after/ the check against __TASK_TRACED, but before the reset of state to TASK_TRACED. This causes it to instead clobber TASK_WAKING, allowing a subsequent wakeup against TRACED while the task is still on the rq wake_list, corrupting it. Oleg said: "The kernel can crash or this can lead to other hard-to-debug problems. In short, "task->state = TASK_TRACED" in ptrace_unfreeze_traced() assumes that nobody else can wake it up, but PTRACE_LISTEN breaks the contract. Obviusly it is very wrong to manipulate task->state if this task is already running, or WAKING, or it sleeps again" [akpm@linux-foundation.org: coding-style fixes] Fixes: 9899d11f ("ptrace: ensure arch_ptrace/ptrace_request can never race with SIGKILL") Link: http://lkml.kernel.org/r/xm26y3vfhmkp.fsf_-_@bsegall-linux.mtv.corp.google.com Signed-off-by: Ben Segall <bsegall@google.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
* perf/core: Fix event inheritance on fork()Peter Zijlstra2017-06-171-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit e7cc4865f0f31698ef2f7aac01a50e78968985b7 upstream. While hunting for clues to a use-after-free, Oleg spotted that perf_event_init_context() can loose an error value with the result that fork() can succeed even though we did not fully inherit the perf event context. Spotted-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: oleg@redhat.com Fixes: 889ff0150661 ("perf/core: Split context's event group list into pinned and non-pinned lists") Link: http://lkml.kernel.org/r/20170316125823.190342547@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Willy Tarreau <w@1wt.eu>
* locking/static_keys: Add static_key_{en,dis}able() helpersPeter Zijlstra2017-06-171-4/+2
| | | | | | | | | | | | | | | | | | | | | | | commit e33886b38cc82a9fc3b2d655dfc7f50467594138 upstream. Add two helpers to make it easier to treat the refcount as boolean. [js] do not involve WARN_ON_ONCE as it causes build failures Suggested-by: Jason Baron <jasonbaron0@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz> [wt: only backported for use in next fix ; s/static_key_count(key)/atomic_read(&key->enabled)/] Signed-off-by: Willy Tarreau <w@1wt.eu>
* hotplug: Make register and unregister notifier API symmetricMichal Hocko2017-06-171-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 777c6e0daebb3fcefbbd6f620410a946b07ef6d0 upstream. Yu Zhao has noticed that __unregister_cpu_notifier only unregisters its notifiers when HOTPLUG_CPU=y while the registration might succeed even when HOTPLUG_CPU=n if MODULE is enabled. This means that e.g. zswap might keep a stale notifier on the list on the manual clean up during the pool tear down and thus corrupt the list. Resulting in the following [ 144.964346] BUG: unable to handle kernel paging request at ffff880658a2be78 [ 144.971337] IP: [<ffffffffa290b00b>] raw_notifier_chain_register+0x1b/0x40 <snipped> [ 145.122628] Call Trace: [ 145.125086] [<ffffffffa28e5cf8>] __register_cpu_notifier+0x18/0x20 [ 145.131350] [<ffffffffa2a5dd73>] zswap_pool_create+0x273/0x400 [ 145.137268] [<ffffffffa2a5e0fc>] __zswap_param_set+0x1fc/0x300 [ 145.143188] [<ffffffffa2944c1d>] ? trace_hardirqs_on+0xd/0x10 [ 145.149018] [<ffffffffa2908798>] ? kernel_param_lock+0x28/0x30 [ 145.154940] [<ffffffffa2a3e8cf>] ? __might_fault+0x4f/0xa0 [ 145.160511] [<ffffffffa2a5e237>] zswap_compressor_param_set+0x17/0x20 [ 145.167035] [<ffffffffa2908d3c>] param_attr_store+0x5c/0xb0 [ 145.172694] [<ffffffffa290848d>] module_attr_store+0x1d/0x30 [ 145.178443] [<ffffffffa2b2b41f>] sysfs_kf_write+0x4f/0x70 [ 145.183925] [<ffffffffa2b2a5b9>] kernfs_fop_write+0x149/0x180 [ 145.189761] [<ffffffffa2a99248>] __vfs_write+0x18/0x40 [ 145.194982] [<ffffffffa2a9a412>] vfs_write+0xb2/0x1a0 [ 145.200122] [<ffffffffa2a9a732>] SyS_write+0x52/0xa0 [ 145.205177] [<ffffffffa2ff4d97>] entry_SYSCALL_64_fastpath+0x12/0x17 This can be even triggered manually by changing /sys/module/zswap/parameters/compressor multiple times. Fix this issue by making unregister APIs symmetric to the register so there are no surprises. [js] backport to 3.12 Fixes: 47e627bc8c9a ("[PATCH] hotplug: Allow modules to use the cpu hotplug notifiers even if !CONFIG_HOTPLUG_CPU") Reported-and-tested-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: linux-mm@kvack.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Streetman <ddstreet@ieee.org> Link: http://lkml.kernel.org/r/20161207135438.4310-1-mhocko@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Willy Tarreau <w@1wt.eu>
* locking/rtmutex: Prevent dequeue vs. unlock raceThomas Gleixner2017-06-171-2/+66
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit dbb26055defd03d59f678cb5f2c992abe05b064a upstream. David reported a futex/rtmutex state corruption. It's caused by the following problem: CPU0 CPU1 CPU2 l->owner=T1 rt_mutex_lock(l) lock(l->wait_lock) l->owner = T1 | HAS_WAITERS; enqueue(T2) boost() unlock(l->wait_lock) schedule() rt_mutex_lock(l) lock(l->wait_lock) l->owner = T1 | HAS_WAITERS; enqueue(T3) boost() unlock(l->wait_lock) schedule() signal(->T2) signal(->T3) lock(l->wait_lock) dequeue(T2) deboost() unlock(l->wait_lock) lock(l->wait_lock) dequeue(T3) ===> wait list is now empty deboost() unlock(l->wait_lock) lock(l->wait_lock) fixup_rt_mutex_waiters() if (wait_list_empty(l)) { owner = l->owner & ~HAS_WAITERS; l->owner = owner ==> l->owner = T1 } lock(l->wait_lock) rt_mutex_unlock(l) fixup_rt_mutex_waiters() if (wait_list_empty(l)) { owner = l->owner & ~HAS_WAITERS; cmpxchg(l->owner, T1, NULL) ===> Success (l->owner = NULL) l->owner = owner ==> l->owner = T1 } That means the problem is caused by fixup_rt_mutex_waiters() which does the RMW to clear the waiters bit unconditionally when there are no waiters in the rtmutexes rbtree. This can be fatal: A concurrent unlock can release the rtmutex in the fastpath because the waiters bit is not set. If the cmpxchg() gets in the middle of the RMW operation then the previous owner, which just unlocked the rtmutex is set as the owner again when the write takes place after the successfull cmpxchg(). The solution is rather trivial: verify that the owner member of the rtmutex has the waiters bit set before clearing it. This does not require a cmpxchg() or other atomic operations because the waiters bit can only be set and cleared with the rtmutex wait_lock held. It's also safe against the fast path unlock attempt. The unlock attempt via cmpxchg() will either see the bit set and take the slowpath or see the bit cleared and release it atomically in the fastpath. It's remarkable that the test program provided by David triggers on ARM64 and MIPS64 really quick, but it refuses to reproduce on x86-64, while the problem exists there as well. That refusal might explain that this got not discovered earlier despite the bug existing from day one of the rtmutex implementation more than 10 years ago. Thanks to David for meticulously instrumenting the code and providing the information which allowed to decode this subtle problem. Reported-by: David Daney <ddaney@caviumnetworks.com> Tested-by: David Daney <david.daney@cavium.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Fixes: 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") Link: http://lkml.kernel.org/r/20161130210030.351136722@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> [wt: s/{READ,WRITE}_ONCE/ACCESS_ONCE/] Signed-off-by: Willy Tarreau <w@1wt.eu>
* Revert "jiffies conversions: Use compile time constants when possible"Mister Oyster2017-06-021-12/+94
| | | | | Build breaks when any of this code is included This reverts commit 9722cd7360077819a5af4937c0f742149fcec82c.
* fs: add dirtytime_expire_seconds sysctlTheodore Ts'o2017-05-291-0/+8
| | | | | | | | Add a tuning knob so we can adjust the dirtytime expiration timeout, which is very useful for testing lazytime. Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz>
* sched: add bit_wait_io for 3.18 ext4 backportTheodore Ts'o2017-05-271-0/+9
| | | | | | | Excerpted from commit 743162013: "sched: Remove proliferation of wait_on_bit() action functions" Signed-off-by: Theodore Ts'o <tytso@mit.edu>
* nohz: Avoid tick's double reprogramming in highres modeViresh Kumar2017-05-241-0/+4
| | | | | | | | | | | | | | | | | | | | | In highres mode, the tick reschedules itself unconditionally to the next jiffies. However while this clock reprogramming is relevant when the tick is in periodic mode, it's not that interesting when we run in dynticks mode because irq exit is likely going to overwrite the next tick to some randomly deferred future. So lets just get rid of this tick self rescheduling in dynticks mode. This way we can avoid some clockevents double write in favourable scenarios like when we stop the tick completely in idle while no other hrtimer is pending. Change-Id: I4e73da9bffbcac49789e5f279b67873f414b22a8 Suggested-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* nohz: Fix spurious periodic tick behaviour in low-res dynticks modeViresh Kumar2017-05-241-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we reach the end of the tick handler, we unconditionally reschedule the next tick to the next jiffy. Then on irq exit, the nohz code overrides that setting if needed and defers the next tick as far away in the future as possible. Now in the best dynticks case, when we actually don't need any tick in the future (ie: expires == KTIME_MAX), low-res and high-res behave differently. What we want in this case is to cancel the next tick programmed by the previous one. That's what we do in high-res mode. OTOH we lack a low-res mode equivalent of hrtimer_cancel() so we simply don't do anything in this case and the next tick remains scheduled to jiffies + 1. As a result, in low-res mode, when the dynticks code determines that no tick is needed in the future, we can recursively get a spurious tick every jiffy because then the next tick is always reprogrammed from the tick handler and is never cancelled. And this can happen indefinetly until some subsystem actually needs a precise tick in the future and only then we eventually overwrite the previous tick handler setting to defer the next tick. We are fixing this by introducing the ONESHOT_STOPPED mode which will let us pause a clockevent when no further interrupt is needed. Meanwhile we can't expect all drivers to support this new mode. So lets reduce much of the symptoms by skipping the nohz-blind tick rescheduling from the tick-handler when the CPU is in dynticks mode. That tick rescheduling wrongly assumed periodicity and the low-res dynticks code can't cancel such decision. This breaks the recursive (and thus the worst) part of the problem. In the worst case now, we'll get only one extra tick due to uncancelled tick scheduled before we entered dynticks mode. This also removes a needless clockevent write on idle ticks. Since those clock write are usually considered to be slow, it's a general win. Change-Id: Id416f55d0356c0f3d178e87d9821ea50d2e1ed69 Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* nohz: Get timekeeping max deferment outside jiffies_lockFrederic Weisbecker2017-05-241-1/+2
| | | | | | | | | | | | | | | | | | | | | We don't need to fetch the timekeeping max deferment under the jiffies_lock seqlock. If the clocksource is updated concurrently while we stop the tick, stop machine is called and the tick will be reevaluated again along with uptodate jiffies and its related values. Change-Id: I2889f0b3da1be1b78dfc74e62986deaafd27b679 Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alex Shi <alex.shi@linaro.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Kevin Hilman <khilman@linaro.org> Link: http://lkml.kernel.org/r/1387320692-28460-9-git-send-email-fweisbec@gmail.com Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
* kernel: Only expose su when daemon is runningTom Marshall2017-05-213-0/+39
| | | | | | | | | | | | | | It has been claimed that the PG implementation of 'su' has security vulnerabilities even when disabled. Unfortunately, the people that find these vulnerabilities often like to keep them private so they can profit from exploits while leaving users exposed to malicious hackers. In order to reduce the attack surface for vulnerabilites, it is therefore necessary to make 'su' completely inaccessible when it is not in use (except by the root and system users). Change-Id: I79716c72f74d0b7af34ec3a8054896c6559a181d
* UPSTREAM: tracing: Fix trace_printk() to print when not using bprintk()Joe Maples2017-05-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The trace_printk() code will allocate extra buffers if the compile detects that a trace_printk() is used. To do this, the format of the trace_printk() is saved to the __trace_printk_fmt section, and if that section is bigger than zero, the buffers are allocated (along with a message that this has happened). If trace_printk() uses a format that is not a constant, and thus something not guaranteed to be around when the print happens, the compiler optimizes the fmt out, as it is not used, and the __trace_printk_fmt section is not filled. This means the kernel will not allocate the special buffers needed for the trace_printk() and the trace_printk() will not write anything to the tracing buffer. Adding a "__used" to the variable in the __trace_printk_fmt section will keep it around, even though it is set to NULL. This will keep the string from being printed in the debugfs/tracing/printk_formats section as it is not needed. Reported-by: Vlastimil Babka <vbabka@suse.cz> Fixes: 07d777fe8c398 "tracing: Add percpu buffers for trace_printk()" Cc: stable@vger.kernel.org # v3.5+ Bug: 34277115 Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Change-Id: I10ce56caa41c7644d9d290d9ed272a6d156c938c Signed-off-by: Joe Maples <joe@frap129.org>
* perf: don't leave group_entry on sibling list (use-after-free)John Dias2017-05-071-0/+7
| | | | | | | | | | | | | When perf_group_detach is called on a group leader, it should empty its sibling list. Otherwise, when a sibling is later deallocated, list_del_event() removes the sibling's group_entry from its current list, which can be the now-deallocated group leader's sibling list (use-after-free bug). Bug: 32402548 Change-Id: I99f6bc97c8518df1cb0035814368012ba72ab1f1 Signed-off-by: John Dias <joaodias@google.com>
* um: fix buildMister Oyster2017-05-041-0/+2
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* BACKPORT: trace: resolve stack corruption due to string copyAmey Telawane2017-05-021-1/+1
| | | | | | | | | | | Strcpy has no limit on string being copied which causes stack corruption leading to kernel panic. Use strlcpy to resolve the issue by providing length of string to be copied. CRs-fixed: 1048480 Bug: 35399704 Change-Id: Ib290b25f7e0ff96927b8530e5c078869441d409f Signed-off-by: Amey Telawane <ameyt@codeaurora.org>
* tracing: do not leak kernel addressesNick Desaulniers2017-05-021-1/+1
| | | | | | | | This likely breaks tracing tools like trace-cmd. It logs in the same format but now addresses are all 0x0. Bug: 34277115 Change-Id: Ifb0d4d2a184bf0d95726de05b1acee0287a375d9
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