talos-obmc-linux/include/linux/sched.h, branch dev-4.13-fsi

pids: make task_tgid_nr_ns() safe

2017-08-21T19:47:31+00:00

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 Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds

Merge tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2017-07-19T15:55:18+00:00

Pull structure randomization updates from Kees Cook: "Now that IPC and other changes have landed, enable manual markings for randstruct plugin, including the task_struct. This is the rest of what was staged in -next for the gcc-plugins, and comes in three patches, largest first: - mark "easy" structs with __randomize_layout - mark task_struct with an optional anonymous struct to isolate the __randomize_layout section - mark structs to opt _out_ of automated marking (which will come later) And, FWIW, this continues to pass allmodconfig (normal and patched to enable gcc-plugins) builds of x86_64, i386, arm64, arm, powerpc, and s390 for me" * tag 'gcc-plugins-v4.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: randstruct: opt-out externally exposed function pointer structs task_struct: Allow randomized layout randstruct: Mark various structs for randomization

fault-inject: parse as natural 1-based value for fail-nth write interface

2017-07-14T22:05:13+00:00

The value written to fail-nth file is parsed as 0-based. Parsing as one-based is more natural to understand and it enables to cancel the previous setup by simply writing '0'. This change also converts task->fail_nth from signed to unsigned int. Link: http://lkml.kernel.org/r/1491490561-10485-3-git-send-email-akinobu.mita@gmail.com Signed-off-by: Akinobu Mita Cc: Dmitry Vyukov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fault-inject: support systematic fault injection

2017-07-12T23:26:01+00:00

Add /proc/self/task//fail-nth file that allows failing 0-th, 1-st, 2-nd and so on calls systematically. Excerpt from the added documentation: "Write to this file of integer N makes N-th call in the current task fail (N is 0-based). Read from this file returns a single char 'Y' or 'N' that says if the fault setup with a previous write to this file was injected or not, and disables the fault if it wasn't yet injected. Note that this file enables all types of faults (slab, futex, etc). This setting takes precedence over all other generic settings like probability, interval, times, etc. But per-capability settings (e.g. fail_futex/ignore-private) take precedence over it. This feature is intended for systematic testing of faults in a single system call. See an example below" Why add a new setting: 1. Existing settings are global rather than per-task. So parallel testing is not possible. 2. attr->interval is close but it depends on attr->count which is non reset to 0, so interval does not work as expected. 3. Trying to model this with existing settings requires manipulations of all of probability, interval, times, space, task-filter and unexposed count and per-task make-it-fail files. 4. Existing settings are per-failure-type, and the set of failure types is potentially expanding. 5. make-it-fail can't be changed by unprivileged user and aggressive stress testing better be done from an unprivileged user. Similarly, this would require opening the debugfs files to the unprivileged user, as he would need to reopen at least times file (not possible to pre-open before dropping privs). The proposed interface solves all of the above (see the example). We want to integrate this into syzkaller fuzzer. A prototype has found 10 bugs in kernel in first day of usage: https://groups.google.com/forum/#!searchin/syzkaller/%22FAULT_INJECTION%22%7Csort:relevance I've made the current interface work with all types of our sandboxes. For setuid the secret sauce was prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) to make /proc entries non-root owned. So I am fine with the current version of the code. [akpm@linux-foundation.org: fix build] Link: http://lkml.kernel.org/r/20170328130128.101773-1-dvyukov@google.com Signed-off-by: Dmitry Vyukov Cc: Akinobu Mita Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

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

2017-07-09T17:52:16+00:00

Pull scheduler fixes from Thomas Gleixner: "This scheduler update provides: - The (hopefully) final fix for the vtime accounting issues which were around for quite some time - Use types known to user space in UAPI headers to unbreak user space builds - Make load balancing respect the current scheduling domain again instead of evaluating unrelated CPUs" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/headers/uapi: Fix linux/sched/types.h userspace compilation errors sched/fair: Fix load_balance() affinity redo path sched/cputime: Accumulate vtime on top of nsec clocksource sched/cputime: Move the vtime task fields to their own struct sched/cputime: Rename vtime fields sched/cputime: Always set tsk->vtime_snap_whence after accounting vtime vtime, sched/cputime: Remove vtime_account_user() Revert "sched/cputime: Refactor the cputime_adjust() code"

mm, mempolicy: stop adjusting current->il_next in mpol_rebind_nodemask()

2017-07-06T23:24:34+00:00

The task->il_next variable stores the next allocation node id for task's MPOL_INTERLEAVE policy. mpol_rebind_nodemask() updates interleave and bind mempolicies due to changing cpuset mems. Currently it also tries to make sure that current->il_next is valid within the updated nodemask. This is bogus, because 1) we are updating potentially any task's mempolicy, not just current, and 2) we might be updating a per-vma mempolicy, not task one. The interleave_nodes() function that uses il_next can cope fine with the value not being within the currently allowed nodes, so this hasn't manifested as an actual issue. We can remove the need for updating il_next completely by changing it to il_prev and store the node id of the previous interleave allocation instead of the next id. Then interleave_nodes() can calculate the next id using the current nodemask and also store it as il_prev, except when querying the next node via do_get_mempolicy(). Link: http://lkml.kernel.org/r/20170517081140.30654-3-vbabka@suse.cz Signed-off-by: Vlastimil Babka Reviewed-by: Christoph Lameter Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Anshuman Khandual Cc: David Rientjes Cc: Dimitri Sivanich Cc: Hugh Dickins Cc: Li Zefan Cc: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched/cputime: Accumulate vtime on top of nsec clocksource

2017-07-05T07:54:15+00:00

Currently the cputime source used by vtime is jiffies. When we cross a context boundary and jiffies have changed since the last snapshot, the pending cputime is accounted to the switching out context. This system works ok if the ticks are not aligned across CPUs. If they instead are aligned (ie: all fire at the same time) and the CPUs run in userspace, the jiffies change is only observed on tick exit and therefore the user cputime is accounted as system cputime. This is because the CPU that maintains timekeeping fires its tick at the same time as the others. It updates jiffies in the middle of the tick and the other CPUs see that update on IRQ exit: CPU 0 (timekeeper) CPU 1 ------------------- ------------- jiffies = N ... run in userspace for a jiffy tick entry tick entry (sees jiffies = N) set jiffies = N + 1 tick exit tick exit (sees jiffies = N + 1) account 1 jiffy as stime Fix this with using a nanosec clock source instead of jiffies. The cputime is then accumulated and flushed everytime the pending delta reaches a jiffy in order to mitigate the accounting overhead. [ fweisbec: changelog, rebase on struct vtime, field renames, add delta on cputime readers, keep idle vtime as-is (low overhead accounting), harmonize clock sources. ] Suggested-by: Thomas Gleixner Reported-by: Luiz Capitulino Tested-by: Luiz Capitulino Signed-off-by: Wanpeng Li Signed-off-by: Frederic Weisbecker Reviewed-by: Thomas Gleixner Acked-by: Rik van Riel Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Wanpeng Li Link: http://lkml.kernel.org/r/1498756511-11714-6-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar

sched/cputime: Move the vtime task fields to their own struct

2017-07-05T07:54:15+00:00

We are about to add vtime accumulation fields to the task struct. Let's avoid more bloatification and gather vtime information to their own struct. Tested-by: Luiz Capitulino Signed-off-by: Frederic Weisbecker Reviewed-by: Thomas Gleixner Acked-by: Rik van Riel Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Wanpeng Li Link: http://lkml.kernel.org/r/1498756511-11714-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar

sched/cputime: Rename vtime fields

2017-07-05T07:54:14+00:00

The current "snapshot" based naming on vtime fields suggests we record some past event but that's a low level picture of their actual purpose which comes out blurry. The real point of these fields is to run a basic state machine that tracks down cputime entry while switching between contexts. So lets reflect that with more meaningful names. Tested-by: Luiz Capitulino Signed-off-by: Frederic Weisbecker Reviewed-by: Thomas Gleixner Acked-by: Rik van Riel Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Wanpeng Li Link: http://lkml.kernel.org/r/1498756511-11714-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar

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

2017-07-04T01:08:06+00:00

Pull SMP hotplug updates from Thomas Gleixner: "This update is primarily a cleanup of the CPU hotplug locking code. The hotplug locking mechanism is an open coded RWSEM, which allows recursive locking. The main problem with that is the recursive nature as it evades the full lockdep coverage and hides potential deadlocks. The rework replaces the open coded RWSEM with a percpu RWSEM and establishes full lockdep coverage that way. The bulk of the changes fix up recursive locking issues and address the now fully reported potential deadlocks all over the place. Some of these deadlocks have been observed in the RT tree, but on mainline the probability was low enough to hide them away." * 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (37 commits) cpu/hotplug: Constify attribute_group structures powerpc: Only obtain cpu_hotplug_lock if called by rtasd ARM/hw_breakpoint: Fix possible recursive locking for arch_hw_breakpoint_init cpu/hotplug: Remove unused check_for_tasks() function perf/core: Don't release cred_guard_mutex if not taken cpuhotplug: Link lock stacks for hotplug callbacks acpi/processor: Prevent cpu hotplug deadlock sched: Provide is_percpu_thread() helper cpu/hotplug: Convert hotplug locking to percpu rwsem s390: Prevent hotplug rwsem recursion arm: Prevent hotplug rwsem recursion arm64: Prevent cpu hotplug rwsem recursion kprobes: Cure hotplug lock ordering issues jump_label: Reorder hotplug lock and jump_label_lock perf/tracing/cpuhotplug: Fix locking order ACPI/processor: Use cpu_hotplug_disable() instead of get_online_cpus() PCI: Replace the racy recursion prevention PCI: Use cpu_hotplug_disable() instead of get_online_cpus() perf/x86/intel: Drop get_online_cpus() in intel_snb_check_microcode() x86/perf: Drop EXPORT of perf_check_microcode ...