user/sven/linux.git/kernel/sched/fair.c, branch v3.4.70

sched/fair: Fix small race where child->se.parent,cfs_rq might point to invalid ones

2013-10-01T16:10:51Z

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: [] sched_slice+0x6e/0xa0 [...] Call Trace: [] place_entity+0x75/0xa0 [] task_fork_fair+0xaa/0x160 [] sched_fork+0x6b/0x140 [] copy_process+0x5b2/0x1450 [] ? wake_up_new_task+0xd9/0x130 [] do_fork+0x94/0x460 [] ? sys_wait4+0xae/0x100 [] sys_clone+0x28/0x30 [] stub_clone+0x13/0x20 [] ? system_call_fastpath+0x16/0x1b Signed-off-by: Daisuke Nishimura Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/039601ceae06$733d3130$59b79390$@mxp.nes.nec.co.jp Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sched: Fix the broken sched_rr_get_interval()

2013-08-11T22:38:43Z

commit a59f4e079d19464eebb9b06513a1d4f55fdae5ba upstream. The caller of sched_sliced() should pass se.cfs_rq and se as the arguments, however in sched_rr_get_interval() we gave it rq.cfs_rq and se, which made the following computation obviously wrong. The change was introduced by commit: 77034937dc45 sched: fix crash in sys_sched_rr_get_interval() ... 5 years ago, while it had been the correct 'cfs_rq_of' before the commit. The change seems to be irrelevant to the commit msg, which was to return a 0 timeslice for tasks that are on an idle runqueue. So I believe that was just a plain typo. Signed-off-by: Zhu Yanhai Cc: Peter Zijlstra Cc: Paul Turner Cc: Thomas Gleixner Cc: Steven Rostedt Cc: Andrew Morton Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1357621012-15039-1-git-send-email-gaoyang.zyh@taobao.com [ Since this is an ABI and an old bug, we'll test this via a slow upstream route, to hopefully discover any app breakage. ] Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

sched: Fix more load-balancing fallout

2012-04-26T10:54:52Z

Commits 367456c756a6 ("sched: Ditch per cgroup task lists for load-balancing") and 5d6523ebd ("sched: Fix load-balance wreckage") left some more wreckage. By setting loop_max unconditionally to ->nr_running load-balancing could take a lot of time on very long runqueues (hackbench!). So keep the sysctl as max limit of the amount of tasks we'll iterate. Furthermore, the min load filter for migration completely fails with cgroups since inequality in per-cpu state can easily lead to such small loads :/ Furthermore the change to add new tasks to the tail of the queue instead of the head seems to have some effect.. not quite sure I understand why. Combined these fixes solve the huge hackbench regression reported by Tim when hackbench is ran in a cgroup. Reported-by: Tim Chen Acked-by: Tim Chen Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/1335365763.28150.267.camel@twins [ got rid of the CONFIG_PREEMPT tuning and made small readability edits ] Signed-off-by: Ingo Molnar

Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-03-29T21:46:05Z

Pull scheduler fixes from Ingo Molnar. * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpusets: Remove an unused variable sched/rt: Improve pick_next_highest_task_rt() sched: Fix select_fallback_rq() vs cpu_active/cpu_online sched/x86/smp: Do not enable IRQs over calibrate_delay() sched: Fix compiler warning about declared inline after use MAINTAINERS: Update email address for SCHEDULER and PERF EVENTS

sched: Fix compiler warning about declared inline after use

2012-03-23T09:39:28Z

kernel/sched/fair.c:420: warning: 'account_cfs_rq_runtime' declared inline after being called kernel/sched/fair.c:420: warning: previous declaration of 'account_cfs_rq_runtime' was here kernel/sched/fair.c:1165: warning: 'return_cfs_rq_runtime' declared inlineafter being called kernel/sched/fair.c:1165: warning: previous declaration of 'return_cfs_rq_runtime' was here Reported-by: Andrew Morton Signed-off-by: Peter Zijlstra Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20120321200717.49BB4A024E@akpm.mtv.corp.google.com Signed-off-by: Ingo Molnar

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-03-20T17:31:44Z

Pull scheduler changes for v3.4 from Ingo Molnar * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) printk: Make it compile with !CONFIG_PRINTK sched/x86: Fix overflow in cyc2ns_offset sched: Fix nohz load accounting -- again! sched: Update yield() docs printk/sched: Introduce special printk_sched() for those awkward moments sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer sched: Cleanup cpu_active madness sched: Fix load-balance wreckage sched: Clean up parameter passing of proc_sched_autogroup_set_nice() sched: Ditch per cgroup task lists for load-balancing sched: Rename load-balancing fields sched: Move load-balancing arguments into helper struct sched/rt: Do not submit new work when PI-blocked sched/rt: Prevent idle task boosting sched/wait: Add __wake_up_all_locked() API sched/rt: Document scheduler related skip-resched-check sites sched/rt: Use schedule_preempt_disabled() sched/rt: Add schedule_preempt_disabled() sched/rt: Do not throttle when PI boosting sched/rt: Keep period timer ticking when rt throttling is active ...

sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer

2012-03-12T19:43:16Z

The 'next_balance' field of 'nohz' idle balancer must be initialized to jiffies. Since jiffies is initialized to negative 300 seconds the 'nohz' idle balancer does not run for the first 300s (5mins) after bootup. If no new processes are spawed or no idle cycles happen, the load on the cpus will remain unbalanced for that duration. Signed-off-by: Diwakar Tundlam Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1DD7BFEDD3147247B1355BEFEFE4665237994F30EF@HQMAIL04.nvidia.com Signed-off-by: Ingo Molnar

sched: Fix load-balance wreckage

2012-03-12T19:43:15Z

Commit 367456c ("sched: Ditch per cgroup task lists for load-balancing") completely wrecked load-balancing due to a few silly mistakes. Correct those and remove more pointless code. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/n/tip-zk04ihygwxn7qqrlpaf73b0r@git.kernel.org Signed-off-by: Ingo Molnar

Merge branch 'perf/urgent' into perf/core

2012-03-05T08:20:08Z

Conflicts: tools/perf/builtin-record.c tools/perf/builtin-top.c tools/perf/perf.h tools/perf/util/top.h Merge reason: resolve these cherry-picking conflicts. Signed-off-by: Ingo Molnar

sched: Ditch per cgroup task lists for load-balancing

2012-03-01T12:08:37Z

Per cgroup load-balance has numerous problems, chief amongst them that there is no real sane order in them. So stop pretending it makes sense and enqueue all tasks on a single list. This also allows us to more easily fix the fwd progress issue uncovered by the lock-break stuff. Rotate the list on failure to migreate and limit the total iterations to nr_running (which with releasing the lock isn't strictly accurate but close enough). Also add a filter that skips very light tasks on the first attempt around the list, this attempts to avoid shooting whole cgroups around without affecting over balance. Signed-off-by: Peter Zijlstra Cc: pjt@google.com Link: http://lkml.kernel.org/n/tip-tx8yqydc7eimgq7i4rkc3a4g@git.kernel.org Signed-off-by: Ingo Molnar