linux/kernel/fork.c, branch v4.3

Revert "sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem"

2015-09-16T15:51:12Z

This reverts commit d59cfc09c32a2ae31f1c3bc2983a0cd79afb3f14. d59cfc09c32a ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem") and b5ba75b5fc0e ("cgroup: simplify threadgroup locking") changed how cgroup synchronizes against task fork and exits so that it uses global percpu_rwsem instead of per-process rwsem; unfortunately, the write [un]lock paths of percpu_rwsem always involve synchronize_rcu_expedited() which turned out to be too expensive. Improvements for percpu_rwsem are scheduled to be merged in the coming v4.4-rc1 merge window which alleviates this issue. For now, revert the two commits to restore per-process rwsem. They will be re-applied for the v4.4-rc1 merge window. Signed-off-by: Tejun Heo Link: http://lkml.kernel.org/g/55F8097A.7000206@de.ibm.com Reported-by: Christian Borntraeger Cc: Oleg Nesterov Cc: "Paul E. McKenney" Cc: Peter Zijlstra Cc: Paolo Bonzini Cc: stable@vger.kernel.org # v4.2+

userfaultfd: add VM_UFFD_MISSING and VM_UFFD_WP

2015-09-04T23:54:41Z

These two flags gets set in vma->vm_flags to tell the VM common code if the userfaultfd is armed and in which mode (only tracking missing faults, only tracking wrprotect faults or both). If neither flags is set it means the userfaultfd is not armed on the vma. Signed-off-by: Andrea Arcangeli Acked-by: Pavel Emelyanov Cc: Sanidhya Kashyap Cc: zhang.zhanghailiang@huawei.com Cc: "Kirill A. Shutemov" Cc: Andres Lagar-Cavilla Cc: Dave Hansen Cc: Paolo Bonzini Cc: Rik van Riel Cc: Mel Gorman Cc: Andy Lutomirski Cc: Hugh Dickins Cc: Peter Feiner Cc: "Dr. David Alan Gilbert" Cc: Johannes Weiner Cc: "Huangpeng (Peter)" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

userfaultfd: add vm_userfaultfd_ctx to the vm_area_struct

2015-09-04T23:54:41Z

This adds the vm_userfaultfd_ctx to the vm_area_struct. Signed-off-by: Andrea Arcangeli Acked-by: Pavel Emelyanov Cc: Sanidhya Kashyap Cc: zhang.zhanghailiang@huawei.com Cc: "Kirill A. Shutemov" Cc: Andres Lagar-Cavilla Cc: Dave Hansen Cc: Paolo Bonzini Cc: Rik van Riel Cc: Mel Gorman Cc: Andy Lutomirski Cc: Hugh Dickins Cc: Peter Feiner Cc: "Dr. David Alan Gilbert" Cc: Johannes Weiner Cc: "Huangpeng (Peter)" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2015-09-02T15:04:23Z

Pull cgroup updates from Tejun Heo: - a new PIDs controller is added. It turns out that PIDs are actually an independent resource from kmem due to the limited PID space. - more core preparations for the v2 interface. Once cpu side interface is settled, it should be ready for lifting the devel mask. for-4.3-unified-base was temporarily branched so that other trees (block) can pull cgroup core changes that blkcg changes depend on. - a non-critical idr_preload usage bug fix. * 'for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: pids: fix invalid get/put usage cgroup: introduce cgroup_subsys->legacy_name cgroup: don't print subsystems for the default hierarchy cgroup: make cftype->private a unsigned long cgroup: export cgrp_dfl_root cgroup: define controller file conventions cgroup: fix idr_preload usage cgroup: add documentation for the PIDs controller cgroup: implement the PIDs subsystem cgroup: allow a cgroup subsystem to reject a fork

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2015-09-01T23:13:25Z

Pull user namespace updates from Eric Biederman: "This finishes up the changes to ensure proc and sysfs do not start implementing executable files, as the there are application today that are only secure because such files do not exist. It akso fixes a long standing misfeature of /proc//mountinfo that did not show the proper source for files bind mounted from /proc//ns/*. It also straightens out the handling of clone flags related to user namespaces, fixing an unnecessary failure of unshare(CLONE_NEWUSER) when files such as /proc//environ are read while is calling unshare. This winds up fixing a minor bug in unshare flag handling that dates back to the first version of unshare in the kernel. Finally, this fixes a minor regression caused by the introduction of sysfs_create_mount_point, which broke someone's in house application, by restoring the size of /sys/fs/cgroup to 0 bytes. Apparently that application uses the directory size to determine if a tmpfs is mounted on /sys/fs/cgroup. The bind mount escape fixes are present in Al Viros for-next branch. and I expect them to come from there. The bind mount escape is the last of the user namespace related security bugs that I am aware of" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: fs: Set the size of empty dirs to 0. userns,pidns: Force thread group sharing, not signal handler sharing. unshare: Unsharing a thread does not require unsharing a vm nsfs: Add a show_path method to fix mountinfo mnt: fs_fully_visible enforce noexec and nosuid if !SB_I_NOEXEC vfs: Commit to never having exectuables on proc and sysfs.

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

2015-09-01T03:26:22Z

Pull scheduler updates from Ingo Molnar: "The biggest change in this cycle is the rewrite of the main SMP load balancing metric: the CPU load/utilization. The main goal was to make the metric more precise and more representative - see the changelog of this commit for the gory details: 9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking") It is done in a way that significantly reduces complexity of the code: 5 files changed, 249 insertions(+), 494 deletions(-) and the performance testing results are encouraging. Nevertheless we need to keep an eye on potential regressions, since this potentially affects every SMP workload in existence. This work comes from Yuyang Du. Other changes: - SCHED_DL updates. (Andrea Parri) - Simplify architecture callbacks by removing finish_arch_switch(). (Peter Zijlstra et al) - cputime accounting: guarantee stime + utime == rtime. (Peter Zijlstra) - optimize idle CPU wakeups some more - inspired by Facebook server loads. (Mike Galbraith) - stop_machine fixes and updates. (Oleg Nesterov) - Introduce the 'trace_sched_waking' tracepoint. (Peter Zijlstra) - sched/numa tweaks. (Srikar Dronamraju) - misc fixes and small cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (44 commits) sched/deadline: Fix comment in enqueue_task_dl() sched/deadline: Fix comment in push_dl_tasks() sched: Change the sched_class::set_cpus_allowed() calling context sched: Make sched_class::set_cpus_allowed() unconditional sched: Fix a race between __kthread_bind() and sched_setaffinity() sched: Ensure a task has a non-normalized vruntime when returning back to CFS sched/numa: Fix NUMA_DIRECT topology identification tile: Reorganize _switch_to() sched, sparc32: Update scheduler comments in copy_thread() sched: Remove finish_arch_switch() sched, tile: Remove finish_arch_switch sched, sh: Fold finish_arch_switch() into switch_to() sched, score: Remove finish_arch_switch() sched, avr32: Remove finish_arch_switch() sched, MIPS: Get rid of finish_arch_switch() sched, arm: Remove finish_arch_switch() sched/fair: Clean up load average references sched/fair: Provide runnable_load_avg back to cfs_rq sched/fair: Remove task and group entity load when they are dead sched/fair: Init cfs_rq's sched_entity load average ...

userns,pidns: Force thread group sharing, not signal handler sharing.

2015-08-12T19:55:28Z

The code that places signals in signal queues computes the uids, gids, and pids at the time the signals are enqueued. Which means that tasks that share signal queues must be in the same pid and user namespaces. Sharing signal handlers is fine, but bizarre. So make the code in fork and userns_install clearer by only testing for what is functionally necessary. Also update the comment in unshare about unsharing a user namespace to be a little more explicit and make a little more sense. Acked-by: Oleg Nesterov Signed-off-by: "Eric W. Biederman"

unshare: Unsharing a thread does not require unsharing a vm

2015-08-12T19:54:26Z

In the logic in the initial commit of unshare made creating a new thread group for a process, contingent upon creating a new memory address space for that process. That is wrong. Two separate processes in different thread groups can share a memory address space and clone allows creation of such proceses. This is significant because it was observed that mm_users > 1 does not mean that a process is multi-threaded, as reading /proc/PID/maps temporarily increments mm_users, which allows other processes to (accidentally) interfere with unshare() calls. Correct the check in check_unshare_flags() to test for !thread_group_empty() for CLONE_THREAD, CLONE_SIGHAND, and CLONE_VM. For sighand->count > 1 for CLONE_SIGHAND and CLONE_VM. For !current_is_single_threaded instead of mm_users > 1 for CLONE_VM. By using the correct checks in unshare this removes the possibility of an accidental denial of service attack. Additionally using the correct checks in unshare ensures that only an explicit unshare(CLONE_VM) can possibly trigger the slow path of current_is_single_threaded(). As an explict unshare(CLONE_VM) is pointless it is not expected there are many applications that make that call. Cc: stable@vger.kernel.org Fixes: b2e0d98705e60e45bbb3c0032c48824ad7ae0704 userns: Implement unshare of the user namespace Reported-by: Ricky Zhou Reported-by: Kees Cook Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman"

sched/cputime: Guarantee stime + utime == rtime

2015-08-03T10:21:21Z

While the current code guarantees monotonicity for stime and utime independently of one another, it does not guarantee that the sum of both is equal to the total time we started out with. This confuses things (and peoples) who look at this sum, like top, and will report >100% usage followed by a matching period of 0%. Rework the code to provide both individual monotonicity and a coherent sum. Suggested-by: Fredrik Markstrom Reported-by: Fredrik Markstrom Tested-by: Fredrik Markstrom Signed-off-by: Peter Zijlstra (Intel) Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Rik van Riel Cc: Stanislaw Gruszka Cc: Thomas Gleixner Cc: jason.low2@hp.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86

2015-07-18T01:42:51Z

Don't burden architectures without dynamic task_struct sizing with the overhead of dynamic sizing. Also optimize the x86 code a bit by caching task_struct_size. Acked-and-Tested-by: Dave Hansen Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1437128892-9831-3-git-send-email-mingo@kernel.org Signed-off-by: Ingo Molnar