- 14 Aug, 2011 28 commits
-
-
Bharata B Rao authored
Basic description of usage and effect for CFS Bandwidth Control. Signed-off-by:
Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by:
Paul Turner <pjt@google.com> Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110721184758.498036116@google.comSigned-off-by:
Ingo Molnar <mingo@elte.hu>
-
Paul Turner authored
When a local cfs_rq blocks we return the majority of its remaining quota to the global bandwidth pool for use by other runqueues. We do this only when the quota is current and there is more than min_cfs_rq_quota [1ms by default] of runtime remaining on the rq. In the case where there are throttled runqueues and we have sufficient bandwidth to meter out a slice, a second timer is kicked off to handle this delivery, unthrottling where appropriate. Using a 'worst case' antagonist which executes on each cpu for 1ms before moving onto the next on a fairly large machine: no quota generations: 197.47 ms /cgroup/a/cpuacct.usage 199.46 ms /cgroup/a/cpuacct.usage 205.46 ms /cgroup/a/cpuacct.usage 198.46 ms /cgroup/a/cpuacct.usage 208.39 ms /cgroup/a/cpuacct.usage Since we are allowed to use "stale" quota our usage is effectively bounded by the rate of input into the global pool and performance is relatively stable. with quota generations [1s increments]: 119.58 ms /cgroup/a/cpuacct.usage 119.65 ms /cgroup/a/cpuacct.usage 119.64 ms /cgroup/a/cpuacct.usage 119.63 ms /cgroup/a/cpuacct.usage 119.60 ms /cgroup/a/cpuacct.usage The large deficit here is due to quota generations (/intentionally/) preventing us from now using previously stranded slack quota. The cost is that this quota becomes unavailable. with quota generations and quota return: 200.09 ms /cgroup/a/cpuacct.usage 200.09 ms /cgroup/a/cpuacct.usage 198.09 ms /cgroup/a/cpuacct.usage 200.09 ms /cgroup/a/cpuacct.usage 200.06 ms /cgroup/a/cpuacct.usage By returning unused quota we're able to both stably consume our desired quota and prevent unintentional overages due to the abuse of slack quota from previous quota periods (especially on a large machine). Signed-off-by:
-
Nikhil Rao authored
This change introduces statistics exports for the cpu sub-system, these are added through the use of a stat file similar to that exported by other subsystems. The following exports are included: nr_periods: number of periods in which execution occurred nr_throttled: the number of periods above in which execution was throttle throttled_time: cumulative wall-time that any cpus have been throttled for this group Signed-off-by:
Nikhil Rao <ncrao@google.com> Signed-off-by:
Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> Signed-off-by:
-
Paul Turner authored
With the machinery in place to throttle and unthrottle entities, as well as handle their participation (or lack there of) we can now enable throttling. There are 2 points that we must check whether it's time to set throttled state: put_prev_entity() and enqueue_entity(). - put_prev_entity() is the typical throttle path, we reach it by exceeding our allocated run-time within update_curr()->account_cfs_rq_runtime() and going through a reschedule. - enqueue_entity() covers the case of a wake-up into an already throttled group. In this case we know the group cannot be on_rq and can throttle immediately. Checks are added at time of put_prev_entity() and enqueue_entity() Signed-off-by:
-
Paul Turner authored
Throttled tasks are invisisble to cpu-offline since they are not eligible for selection by pick_next_task(). The regular 'escape' path for a thread that is blocked at offline is via ttwu->select_task_rq, however this will not handle a throttled group since there are no individual thread wakeups on an unthrottle. Resolve this by unthrottling offline cpus so that threads can be migrated. Signed-off-by:
-
Paul Turner authored
Buddies allow us to select "on-rq" entities without actually selecting them from a cfs_rq's rb_tree. As a result we must ensure that throttled entities are not falsely nominated as buddies. The fact that entities are dequeued within throttle_entity is not sufficient for clearing buddy status as the nomination may occur after throttling. Signed-off-by:
-
Paul Turner authored
From the perspective of load-balance and shares distribution, throttled entities should be invisible. However, both of these operations work on 'active' lists and are not inherently aware of what group hierarchies may be present. In some cases this may be side-stepped (e.g. we could sideload via tg_load_down in load balance) while in others (e.g. update_shares()) it is more difficult to compute without incurring some O(n^2) costs. Instead, track hierarchicaal throttled state at time of transition. This allows us to easily identify whether an entity belongs to a throttled hierarchy and avoid incorrect interactions with it. Also, when an entity leaves a throttled hierarchy we need to advance its time averaging for shares averaging so that the elapsed throttled time is not considered as part of the cfs_rq's operation. We also use this information to prevent buddy interactions in the wakeup and yield_to() paths. Signed-off-by:
-
Paul Turner authored
Extend walk_tg_tree to accept a positional argument static int walk_tg_tree_from(struct task_group *from, tg_visitor down, tg_visitor up, void *data) Existing semantics are preserved, caller must hold rcu_lock() or sufficient analogue. Signed-off-by:
-
Paul Turner authored
At the start of each period we refresh the global bandwidth pool. At this time we must also unthrottle any cfs_rq entities who are now within bandwidth once more (as quota permits). Unthrottled entities have their corresponding cfs_rq->throttled flag cleared and their entities re-enqueued. Signed-off-by:
-
Paul Turner authored
Now that consumption is tracked (via update_curr()) we add support to throttle group entities (and their corresponding cfs_rqs) in the case where this is no run-time remaining. Throttled entities are dequeued to prevent scheduling, additionally we mark them as throttled (using cfs_rq->throttled) to prevent them from becoming re-enqueued until they are unthrottled. A list of a task_group's throttled entities are maintained on the cfs_bandwidth structure. Note: While the machinery for throttling is added in this patch the act of throttling an entity exceeding its bandwidth is deferred until later within the series. Signed-off-by:
-
Paul Turner authored
Since quota is managed using a global state but consumed on a per-cpu basis we need to ensure that our per-cpu state is appropriately synchronized. Most importantly, runtime that is state (from a previous period) should not be locally consumable. We take advantage of existing sched_clock synchronization about the jiffy to efficiently detect whether we have (globally) crossed a quota boundary above. One catch is that the direction of spread on sched_clock is undefined, specifically, we don't know whether our local clock is behind or ahead of the one responsible for the current expiration time. Fortunately we can differentiate these by considering whether the global deadline has advanced. If it has not, then we assume our clock to be "fast" and advance our local expiration; otherwise, we know the deadline has truly passed and we expire our local runtime. Signed-off-by:
-
Paul Turner authored
This patch adds a per-task_group timer which handles the refresh of the global CFS bandwidth pool. Since the RT pool is using a similar timer there's some small refactoring to share this support. Signed-off-by:
-
Paul Turner authored
Account bandwidth usage on the cfs_rq level versus the task_groups to which they belong. Whether we are tracking bandwidth on a given cfs_rq is maintained under cfs_rq->runtime_enabled. cfs_rq's which belong to a bandwidth constrained task_group have their runtime accounted via the update_curr() path, which withdraws bandwidth from the global pool as desired. Updates involving the global pool are currently protected under cfs_bandwidth->lock, local runtime is protected by rq->lock. This patch only assigns and tracks quota, no action is taken in the case that cfs_rq->runtime_used exceeds cfs_rq->runtime_assigned. Signed-off-by:
-
Paul Turner authored
Add constraints validation for CFS bandwidth hierarchies. Validate that: max(child bandwidth) <= parent_bandwidth In a quota limited hierarchy, an unconstrained entity (e.g. bandwidth==RUNTIME_INF) inherits the bandwidth of its parent. This constraint is chosen over sum(child_bandwidth) as notion of over-commit is valuable within SCHED_OTHER. Some basic code from the RT case is re-factored for reuse. Signed-off-by:
-
Paul Turner authored
In this patch we introduce the notion of CFS bandwidth, partitioned into globally unassigned bandwidth, and locally claimed bandwidth. - The global bandwidth is per task_group, it represents a pool of unclaimed bandwidth that cfs_rqs can allocate from. - The local bandwidth is tracked per-cfs_rq, this represents allotments from the global pool bandwidth assigned to a specific cpu. Bandwidth is managed via cgroupfs, adding two new interfaces to the cpu subsystem: - cpu.cfs_period_us : the bandwidth period in usecs - cpu.cfs_quota_us : the cpu bandwidth (in usecs) that this tg will be allowed to consume over period above. Signed-off-by:
-
Paul Turner authored
Introduce hierarchical task accounting for the group scheduling case in CFS, as well as promoting the responsibility for maintaining rq->nr_running to the scheduling classes. The primary motivation for this is that with scheduling classes supporting bandwidth throttling it is possible for entities participating in throttled sub-trees to not have root visible changes in rq->nr_running across activate and de-activate operations. This in turn leads to incorrect idle and weight-per-task load balance decisions. This also allows us to make a small fixlet to the fastpath in pick_next_task() under group scheduling. Note: this issue also exists with the existing sched_rt throttling mechanism. This patch does not address that. Signed-off-by:
-
Yong Zhang authored
Since [sched/cpupri: Remove the vec->lock], member pri_active of struct cpupri is not needed any more, just remove it. Also clean stuff related to it. Signed-off-by:
Yong Zhang <yong.zhang0@gmail.com> Signed-off-by:
-
Steven Rostedt authored
[ This patch actually compiles. Thanks to Mike Galbraith for pointing that out. I compiled and booted this patch with no issues. ] Re-examining the cpupri patch, I see there's a possible race because the update of the two priorities vec->counts are not protected by a memory barrier. When a RT runqueue is overloaded and wants to push an RT task to another runqueue, it scans the RT priority vectors in a loop from lowest priority to highest. When we queue or dequeue an RT task that changes a runqueue's highest priority task, we update the vectors to show that a runqueue is rated at a different priority. To do this, we first set the new priority mask, and increment the vec->count, and then set the old priority mask by decrementing the vec->count. If we are lowering the runqueue's RT priority rating, it will trigger a RT pull, and we do not care if we miss pushing to this runqueue or not. But if we raise the priority, but the priority is still lower than an RT task that is looking to be pushed, we must make sure that this runqueue is still seen by the push algorithm (the loop). Because the loop reads from lowest to highest, and the new priority is set before the old one is cleared, we will either see the new or old priority set and the vector will be checked. But! Since there's no memory barrier between the updates of the two, the old count may be decremented first before the new count is incremented. This means the loop may see the old count of zero and skip it, and also the new count of zero before it was updated. A possible runqueue that the RT task could move to could be missed. A conditional memory barrier is placed between the vec->count updates and is only called when both updates are done. The smp_wmb() has also been changed to smp_mb__before_atomic_inc/dec(), as they are not needed by archs that already synchronize atomic_inc/dec(). The smp_rmb() has been moved to be called at every iteration of the loop so that the race between seeing the two updates is visible by each iteration of the loop, as an arch is free to optimize the reading of memory of the counters in the loop. Signed-off-by:
Steven Rostedt <rostedt@goodmis.org> Signed-off-by:
-
Steven Rostedt authored
sched/cpupri: Remove the vec->lock The cpupri vec->lock has been showing up as a top contention lately. This is because of the RT push/pull logic takes an agressive approach for migrating RT tasks. The cpupri logic is in place to improve the performance of the push/pull when dealing with large number CPU machines. The problem though is a vec->lock is required, where a vec is a global per RT priority structure. That is, if there are lots of RT tasks at the same priority, every time they are added or removed from the RT queue, this global vec->lock is taken. Now that more kernel threads are becoming RT (RCU boost and threaded interrupts) this is becoming much more of an issue. There are two variables that are being synced by the vec->lock. The cpupri bitmask, and the vec->counter. The cpupri bitmask is one bit per priority. If a RT priority vec has a process queued, then the vec->count is > 0 and the cpupri bitmask is set for that RT priority. If the cpupri bitmask gets out of sync with the vec->counter, we could end up pushing a low proirity RT task to a high priority queue. That RT task that could have run immediately could be queued on a run queue with a higher priority task indefinitely. The solution is not to use the cpupri bitmask and just look at the vec->count directly when doing a pull. The cpupri bitmask is just a fast way to scan the RT priorities when a pull is made. Instead of using the bitmask, and just examine all RT priorities, and look at the vec->counts, we could eliminate the vec->lock. The scan of RT tasks is to find a run queue that we can push an RT task to, and we do not push to a high priority queue, thus the scan only needs to go from 1 to RT task->prio, and not all 100 RT priorities. The push algorithm, which does the scan of RT priorities (and scan of the bitmask) only happens when we have an overloaded RT run queue (more than one RT task queued). The grabbing of the vec->lock happens every time any RT task is queued or dequeued on the run queue for that priority. The slowing down of the scan by not using a bitmask is negligible by the speed up of removing the vec->lock contention, and replacing it with an atomic counter and memory barrier. To prove this, I wrote a patch that times both the loop and the code that grabs the vec->locks. I passed the patches to various people (and companies) to test and show the results. I let everyone choose their own load to test, giving different loads on the system, for various different setups. Here's some of the results: (snipping to a few CPUs to not make this change log huge, but the results were consistent across the entire system). System 1 (24 CPUs) Before patch: CPU: Name Count Max Min Average Total ---- ---- ----- --- --- ------- ----- [...] cpu 20: loop 3057 1.766 0.061 0.642 1963.170 vec 6782949 90.469 0.089 0.414 2811760.503 cpu 21: loop 2617 1.723 0.062 0.641 1679.074 vec 6782810 90.499 0.089 0.291 1978499.900 cpu 22: loop 2212 1.863 0.063 0.699 1547.160 vec 6767244 85.685 0.089 0.435 2949676.898 cpu 23: loop 2320 2.013 0.062 0.594 1380.265 vec 6781694 87.923 0.088 0.431 2928538.224 After patch: cpu 20: loop 2078 1.579 0.061 0.533 1108.006 vec 6164555 5.704 0.060 0.143 885185.809 cpu 21: loop 2268 1.712 0.065 0.575 1305.248 vec 6153376 5.558 0.060 0.187 1154960.469 cpu 22: loop 1542 1.639 0.095 0.533 823.249 vec 6156510 5.720 0.060 0.190 1172727.232 cpu 23: loop 1650 1.733 0.068 0.545 900.781 vec 6170784 5.533 0.060 0.167 1034287.953 All times are in microseconds. The 'loop' is the amount of time spent doing the loop across the priorities (before patch uses bitmask). the 'vec' is the amount of time in the code that requires grabbing the vec->lock. The second patch just does not have the vec lock, but encompasses the same code. Amazingly the loop code even went down on average. The vec code went from .5 down to .18, that's more than half the time spent! Note, more than one test was run, but they all had the same results. System 2 (64 CPUs) Before patch: CPU: Name Count Max Min Average Total ---- ---- ----- --- --- ------- ----- cpu 60: loop 0 0 0 0 0 vec 5410840 277.954 0.084 0.782 4232895.727 cpu 61: loop 0 0 0 0 0 vec 4915648 188.399 0.084 0.570 2803220.301 cpu 62: loop 0 0 0 0 0 vec 5356076 276.417 0.085 0.786 4214544.548 cpu 63: loop 0 0 0 0 0 vec 4891837 170.531 0.085 0.799 3910948.833 After patch: cpu 60: loop 0 0 0 0 0 vec 5365118 5.080 0.021 0.063 340490.267 cpu 61: loop 0 0 0 0 0 vec 4898590 1.757 0.019 0.071 347903.615 cpu 62: loop 0 0 0 0 0 vec 5737130 3.067 0.021 0.119 687108.734 cpu 63: loop 0 0 0 0 0 vec 4903228 1.822 0.021 0.071 348506.477 The test run during the measurement did not have any (very few, from other CPUs) RT tasks pushing. But this shows that it helped out tremendously with the contention, as the contention happens because the vec->lock is taken only on queuing at an RT priority, and different CPUs that queue tasks at the same priority will have contention. I tested on my own 4 CPU machine with the following results: Before patch: CPU: Name Count Max Min Average Total ---- ---- ----- --- --- ------- ----- cpu 0: loop 2377 1.489 0.158 0.588 1398.395 vec 4484 770.146 2.301 4.396 19711.755 cpu 1: loop 2169 1.962 0.160 0.576 1250.110 vec 4425 152.769 2.297 4.030 17834.228 cpu 2: loop 2324 1.749 0.155 0.559 1299.799 vec 4368 779.632 2.325 4.665 20379.268 cpu 3: loop 2325 1.629 0.157 0.561 1306.113 vec 4650 408.782 2.394 4.348 20222.577 After patch: CPU: Name Count Max Min Average Total ---- ---- ----- --- --- ------- ----- cpu 0: loop 2121 1.616 0.113 0.636 1349.189 vec 4303 1.151 0.225 0.421 1811.966 cpu 1: loop 2130 1.638 0.178 0.644 1372.927 vec 4627 1.379 0.235 0.428 1983.648 cpu 2: loop 2056 1.464 0.165 0.637 1310.141 vec 4471 1.311 0.217 0.433 1937.927 cpu 3: loop 2154 1.481 0.162 0.601 1295.083 vec 4236 1.253 0.230 0.425 1803.008 This was running my migrate.c code that can be found at: http://lwn.net/Articles/425763/ The migrate code does stress the RT tasks a bit. This shows that the loop did increase a little after the patch, but not by much. The vec code dropped dramatically. From 4.3us down to .42us. That's a 10x improvement! Tested-by:Mike Galbraith <mgalbraith@suse.de> Tested-by:
Luis Claudio R. Gonçalves <lgoncalv@redhat.com> Tested-by: Matthew Hank Sabins<msabins@linux.vnet.ibm.com> Signed-off-by:
Gregory Haskins <gregory.haskins@gmail.com> Acked-by:
Hillf Danton <dhillf@gmail.com> Signed-off-by:
-
Steven Rostedt authored
Hillf Danton proposed a patch (see link) that cleaned up the sched_rt code that calculates the priority of the next highest priority task to be used in finding run queues to pull from. His patch removed the calculating of the next prio to just use the current prio when deteriming if we should examine a run queue to pull from. The problem with his patch was that it caused more false checks. Because we check a run queue for pushable tasks if the current priority of that run queue is higher in priority than the task about to run on our run queue. But after grabbing the locks and doing the real check, we find that there may not be a task that has a higher prio task to pull. Thus the locks were taken with nothing to do. I added some trace_printks() to record when and how many times the run queue locks were taken to check for pullable tasks, compared to how many times we pulled a task. With the current method, it was: 3806 locks taken vs 2812 pulled tasks With Hillf's patch: 6728 locks taken vs 2804 pulled tasks The number of times locks were taken to pull a task went up almost double with no more success rate. But his patch did get me thinking. When we look at the priority of the highest task to consider taking the locks to do a pull, a failure to pull can be one of the following: (in order of most likely) o RT task was pushed off already between the check and taking the lock o Waiting RT task can not be migrated o RT task's CPU affinity does not include the target run queue's CPU o RT task's priority changed between the check and taking the lock And with Hillf's patch, the thing that caused most of the failures, is the RT task to pull was not at the right priority to pull (not greater than the current RT task priority on the target run queue). Most of the above cases we can't help. But the current method does not check if the next highest prio RT task can be migrated or not, and if it can not, we still grab the locks to do the test (we don't find out about this fact until after we have the locks). I thought about this case, and realized that the pushable task plist that is maintained only holds RT tasks that can migrate. If we move the calculating of the next highest prio task from the inc/dec_rt_task() functions into the queuing of the pushable tasks, then we only measure the priorities of those tasks that we push, and we get this basically for free. Not only does this patch make the code a little more efficient, it cleans it up and makes it a little simpler. Thanks to Hillf Danton for inspiring me on this patch. Signed-off-by:
-
Steven Rostedt authored
When a new task is woken, the code to balance the RT task is currently skipped in the select_task_rq() call. But it will be pushed if the rq is currently overloaded with RT tasks anyway. The issue is that we already queued the task, and if it does get pushed, it will have to be dequeued and requeued on the new run queue. The advantage with pushing it first is that we avoid this requeuing as we are pushing it off before the task is ever queued. See commit 318e0893 ("sched: pre-route RT tasks on wakeup") for more details. The return of select_task_rq() when it is not a wake up has also been changed to return task_cpu() instead of smp_processor_id(). This is more of a sanity because the current only other user of select_task_rq() besides wake ups, is an exec, where task_cpu() should also be the same as smp_processor_id(). But if it is used for other purposes, lets keep the task on the same CPU. Why would we mant to migrate it to the current CPU? Signed-off-by:
-
Hillf Danton authored
There's no reason to clean the exec_start in put_prev_task_rt() as it is reset when the task gets back to the run queue. This saves us doing a store() in the fast path. Signed-off-by:
-
Hillf Danton authored
Do not call dequeue_pushable_task() when failing to push an eligible task, as it remains pushable, merely not at this particular moment. Signed-off-by:
Mike Galbraith <mgalbraith@gmx.de> Signed-off-by:
-
Hillf Danton authored
Checking for the validity of sd is removed, since it is already checked by the for_each_domain macro. Signed-off-by:
-
Hillf Danton authored
When computing the next priority for a given run-queue, the check for RT priority of the task determined by the pick_next_highest_task_rt() function could be removed, since only RT tasks are returned by the function. Reviewed-by:
-
Mike Galbraith authored
Setting child->prio = current->normal_prio _after_ SCHED_RESET_ON_FORK has been handled for an RT parent gives birth to a deranged mutant child with non-RT policy, but RT prio and sched_class. Move PI leakage protection up, always set priorities and weight, and if the child is leaving RT class, reset rt_priority to the proper value. Signed-off-by:
Mike Galbraith <efault@gmx.de> Signed-off-by:
-
Yong Zhang authored
Remove the WAKEUP_PREEMPT feature, disabling it doesn't make any sense and its outlived its use by a long long while. Signed-off-by:
-
Jan H. Schönherr authored
Since commit a2d47777 ("sched: fix stale value in average load per task") the variable rq->avg_load_per_task is no longer required. Remove it. Signed-off-by:
Jan H. Schönherr <schnhrr@cs.tu-berlin.de> Signed-off-by:
-
- 12 Aug, 2011 5 commits
-
-
git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparcLinus Torvalds authored
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: sparc: Don't do hypervisor calls on non-sun4v in DS driver.
-
David S. Miller authored
Reported-by:
Pieter-Paul Giesberts <pieterpg@broadcom.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
-
Boaz Harrosh authored
Just like files-layout, blocks & objects layouts are part of the NFS 4.1 protocol and should be automatically selected if NFS_4_1 is selected. The small problem is that these depend on other Kernel support being present, while files only depends on NFS itself. This patch removes from the user choice the presence of objects and blocks layout. But makes sure these are selected only if the depended subsystems are present in the Kernel. Signed-off-by:
Boaz Harrosh <bharrosh@panasas.com> Acked-by:
Peng Tao <peng_tao@emc.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
-
Eric Sandeen authored
Commit df5e6223 ("ext4: fix deadlock in ext4_symlink() in ENOSPC conditions") recalculated the number of credits needed for a long symlink, in the process of splitting it into two transactions. However, the first credit calculation under-counted because if selinux is enabled, credits are needed to create the selinux xattr as well. Overrunning the reservation will result in an OOPS in jbd2_journal_dirty_metadata() due to this assert: J_ASSERT_JH(jh, handle->h_buffer_credits > 0); Fix this by increasing the reservation size. Signed-off-by:
Eric Sandeen <sandeen@redhat.com> Reviewed-by:
Jan Kara <jack@suse.cz> Acked-by:
"Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org Signed-off-by:
-
Eric Sandeen authored
Commit ae54870a ("ext3: Fix lock inversion in ext3_symlink()") recalculated the number of credits needed for a long symlink, in the process of splitting it into two transactions. However, the first credit calculation under-counted because if selinux is enabled, credits are needed to create the selinux xattr as well. Overrunning the reservation will result in an OOPS in journal_dirty_metadata() due to this assert: J_ASSERT_JH(jh, handle->h_buffer_credits > 0); Fix this by increasing the reservation size. Signed-off-by:
-
- 11 Aug, 2011 6 commits
-
-
Vasiliy Kulikov authored
The patch http://lkml.org/lkml/2003/7/13/226 introduced an RLIMIT_NPROC check in set_user() to check for NPROC exceeding via setuid() and similar functions. Before the check there was a possibility to greatly exceed the allowed number of processes by an unprivileged user if the program relied on rlimit only. But the check created new security threat: many poorly written programs simply don't check setuid() return code and believe it cannot fail if executed with root privileges. So, the check is removed in this patch because of too often privilege escalations related to buggy programs. The NPROC can still be enforced in the common code flow of daemons spawning user processes. Most of daemons do fork()+setuid()+execve(). The check introduced in execve() (1) enforces the same limit as in setuid() and (2) doesn't create similar security issues. Neil Brown suggested to track what specific process has exceeded the limit by setting PF_NPROC_EXCEEDED process flag. With the change only this process would fail on execve(), and other processes' execve() behaviour is not changed. Solar Designer suggested to re-check whether NPROC limit is still exceeded at the moment of execve(). If the process was sleeping for days between set*uid() and execve(), and the NPROC counter step down under the limit, the defered execve() failure because NPROC limit was exceeded days ago would be unexpected. If the limit is not exceeded anymore, we clear the flag on successful calls to execve() and fork(). The flag is also cleared on successful calls to set_user() as the limit was exceeded for the previous user, not the current one. Similar check was introduced in -ow patches (without the process flag). v3 - clear PF_NPROC_EXCEEDED on successful calls to set_user(). Reviewed-by:
James Morris <jmorris@namei.org> Signed-off-by:
Vasiliy Kulikov <segoon@openwall.com> Acked-by:
NeilBrown <neilb@suse.de> Signed-off-by:
-
Linus Torvalds authored
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: perf symbols: Check '/tmp/perf-' symbol file ownership perf sched: Usage leftover from trace -> script rename perf sched: Do not delete session object prematurely perf tools: Check $HOME/.perfconfig ownership perf, x86: Add model 45 SandyBridge support perf tools: Add support to install perf python extension perf tools: do not look at ./config for configuration perf tools: Make clean leaves some files perf lock: Dropping unsupported ':r' modifier perf probe: Fix coredump introduced by probe module option jump label: Reduce the cycle count by changing the link order perf report: Use ui__warning in some more places perf python: Add PERF_RECORD_{LOST,READ,SAMPLE} routine tables perf evlist: Introduce 'disable' method trace events: Update version number reference to new 3.x scheme for EVENT_POWER_TRACING_DEPRECATED perf buildid-cache: Zero out buffer of filenames when adding/removing buildid
-
Tracey Dent authored
Change to new git tree - (git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git). Signed-off-by:
Tracey Dent <tdent48227@gmail.com> Acked-by:
WANG Cong <xiyou.wangcong@gmail.com> Signed-off-by:
-
Linus Torvalds authored
This reverts commit af9d220b. It turns out that one was meant to be applied on top of the edac.git tree in -next that has more i7core_edac changes, but that wasn't clear in the original email. Reported-by:
Stephen Rothwell <sfr@canb.auug.org.au> Acked-by:
Borislav Petkov <borislav.petkov@amd.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by:
-
Peng Tao authored
PNFS_BLOCK needs BLK_DEV_DM/MD, which is not a dependency for other pnfs layout drivers. Seperate it out so others can still build when BLK_DEV_DM/MD is not enabled. Also change select to depends on to avoid build failures. Reported-and-tested-by:
Randy Dunlap <rdunlap@xenotime.net> Signed-off-by:
Benny Halevy <bhalevy@tonian.com> Signed-off-by:
-
Linus Torvalds authored
* 'fixes' of master.kernel.org:/home/rmk/linux-2.6-arm: ARM: drop experimental status for ARM_PATCH_PHYS_VIRT ARM: 7008/1: alignment: Make SIGBUS sent to userspace POSIXly correct ARM: 7007/1: alignment: Prevent ignoring of faults with ARMv6 unaligned access model ARM: 7010/1: mm: fix invalid loop for poison_init_mem ARM: 7005/1: freshen up mm/proc-arm946.S dmaengine: PL08x: Fix trivial build error ARM: Fix build error for SMP=n builds
-
- 10 Aug, 2011 1 commit
-
-
git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpcLinus Torvalds authored
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: powerpc: Really fix build without CONFIG_PCI powerpc: Fix build without CONFIG_PCI powerpc/4xx: Fix build of PCI code on 405 powerpc/pseries: Simplify vpa deregistration functions powerpc/pseries: Cleanup VPA registration and deregistration errors powerpc/pseries: Fix kexec on recent firmware versions MAINTAINERS: change maintainership of mpc5xxx powerpc: Make KVM_GUEST default to n powerpc/kvm: Fix build errors with older toolchains powerpc: Lack of ibm,io-events not that important! powerpc: Move kdump default base address to half RMO size on 64bit powerpc/perf: Disable pagefaults during callchain stack read ppc: Remove duplicate definition of PV_POWER7 powerpc: pseries: Fix kexec on machines with more than 4TB of RAM powerpc: Jump label misalignment causes oops at boot powerpc: Clean up some panic messages in prom_init powerpc: Fix device tree claim code powerpc: Return the_cpu_ spec from identify_cpu powerpc: mtspr/mtmsr should take an unsigned long
-
