user/sven/linux.git/kernel/exit.c, branch v4.9.53

sched/autogroup: Do not use autogroup->tg in zombie threads

2016-11-22T11:33:43Z

Exactly because for_each_thread() in autogroup_move_group() can't see it and update its ->sched_task_group before _put() and possibly free(). So the exiting task needs another sched_move_task() before exit_notify() and we need to re-introduce the PF_EXITING (or similar) check removed by the previous change for another reason. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: hartsjc@redhat.com Cc: vbendel@redhat.com Cc: vlovejoy@redhat.com Link: http://lkml.kernel.org/r/20161114184612.GA15968@redhat.com Signed-off-by: Ingo Molnar

mm, oom: enforce exit_oom_victim on current task

2016-10-08T01:46:28Z

There are no users of exit_oom_victim on !current task anymore so enforce the API to always work on the current. Link: http://lkml.kernel.org/r/1472119394-11342-8-git-send-email-mhocko@kernel.org Signed-off-by: Tetsuo Handa Signed-off-by: Michal Hocko Cc: Oleg Nesterov Cc: David Rientjes Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched/core: Optimize __schedule()

2016-09-22T12:53:45Z

Oleg noted that by making do_exit() use __schedule() for the TASK_DEAD context switch, we can avoid the TASK_DEAD special case currently in __schedule() because that avoids the extra preempt_disable() from schedule(). In order to facilitate this, create a do_task_dead() helper which we place in the scheduler code, such that it can access __schedule(). Also add some __noreturn annotations to the functions, there's no coming back from do_exit(). Suggested-by: Oleg Nesterov Signed-off-by: Peter Zijlstra (Intel) Cc: Cheng Chao Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: akpm@linux-foundation.org Cc: chris@chris-wilson.co.uk Cc: tj@kernel.org Link: http://lkml.kernel.org/r/20160913163729.GB5012@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar

mm, mempolicy: task->mempolicy must be NULL before dropping final reference

2016-09-02T00:52:01Z

KASAN allocates memory from the page allocator as part of kmem_cache_free(), and that can reference current->mempolicy through any number of allocation functions. It needs to be NULL'd out before the final reference is dropped to prevent a use-after-free bug: BUG: KASAN: use-after-free in alloc_pages_current+0x363/0x370 at addr ffff88010b48102c CPU: 0 PID: 15425 Comm: trinity-c2 Not tainted 4.8.0-rc2+ #140 ... Call Trace: dump_stack kasan_object_err kasan_report_error __asan_report_load2_noabort alloc_pages_current <-- use after free depot_save_stack save_stack kasan_slab_free kmem_cache_free __mpol_put <-- free do_exit This patch sets current->mempolicy to NULL before dropping the final reference. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1608301442180.63329@chino.kir.corp.google.com Fixes: cd11016e5f52 ("mm, kasan: stackdepot implementation. Enable stackdepot for SLAB") Signed-off-by: David Rientjes Reported-by: Vegard Nossum Acked-by: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: [4.6+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/exit.c: quieten greatest stack depth printk

2016-08-02T23:35:23Z

Many targets enable CONFIG_DEBUG_STACK_USAGE, and while the information is useful, it isn't worthy of pr_warn(). Reduce it to pr_info(). Link: http://lkml.kernel.org/r/1466982072-29836-1-git-send-email-anton@ozlabs.org Signed-off-by: Anton Blanchard Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

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

2016-07-25T20:59:34Z

Pull scheduler updates from Ingo Molnar: - introduce and use task_rcu_dereference()/try_get_task_struct() to fix and generalize task_struct handling (Oleg Nesterov) - do various per entity load tracking (PELT) fixes and optimizations (Peter Zijlstra) - cputime virt-steal time accounting enhancements/fixes (Wanpeng Li) - introduce consolidated cputime output file cpuacct.usage_all and related refactorings (Zhao Lei) - ... plus misc fixes and enhancements * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Panic on scheduling while atomic bugs if kernel.panic_on_warn is set sched/cpuacct: Introduce cpuacct.usage_all to show all CPU stats together sched/cpuacct: Use loop to consolidate code in cpuacct_stats_show() sched/cpuacct: Merge cpuacct_usage_index and cpuacct_stat_index enums sched/fair: Rework throttle_count sync sched/core: Fix sched_getaffinity() return value kerneldoc comment sched/fair: Reorder cgroup creation code sched/fair: Apply more PELT fixes sched/fair: Fix PELT integrity for new tasks sched/cgroup: Fix cpu_cgroup_fork() handling sched/fair: Fix PELT integrity for new groups sched/fair: Fix and optimize the fork() path sched/cputime: Add steal time support to full dynticks CPU time accounting sched/cputime: Fix prev steal time accouting during CPU hotplug KVM: Fix steal clock warp during guest CPU hotplug sched/debug: Always show 'nr_migrations' sched/fair: Use task_rcu_dereference() sched/api: Introduce task_rcu_dereference() and try_get_task_struct() sched/idle: Optimize the generic idle loop sched/fair: Fix the wrong throttled clock time for cfs_rq_clock_task()

locking/spinlock: Update spin_unlock_wait() users

2016-06-14T09:55:15Z

With the modified semantics of spin_unlock_wait() a number of explicit barriers can be removed. Also update the comment for the do_exit() usecase, as that was somewhat stale/obscure. Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/api: Introduce task_rcu_dereference() and try_get_task_struct()

2016-06-03T07:18:57Z

Generally task_struct is only protected by RCU if it was found on a RCU protected list (say, for_each_process() or find_task_by_vpid()). As Kirill pointed out rq->curr isn't protected by RCU, the scheduler drops the (potentially) last reference without RCU gp, this means that we need to fix the code which uses foreign_rq->curr under rcu_read_lock(). Add a new helper which can be used to dereference rq->curr or any other pointer to task_struct assuming that it should be cleared or updated before the final put_task_struct(). It returns non-NULL only if this task can't go away before rcu_read_unlock(). ( Also add try_get_task_struct() to make it easier to use this API correctly. ) Suggested-by: Kirill Tkhai Signed-off-by: Oleg Nesterov [ Updated comments; added try_get_task_struct()] Signed-off-by: Peter Zijlstra (Intel) Cc: Chris Metcalf Cc: Christoph Lameter Cc: Kirill Tkhai Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Vladimir Davydov Link: http://lkml.kernel.org/r/20160518170218.GY3192@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar

wait: allow sys_waitid() to accept WNOTHREAD/WCLONE/__WALL

2016-05-24T00:04:14Z

I see no reason why waitid() can't support other linux-specific flags allowed in sys_wait4(). In particular this change can help if we reconsider the previous change ("wait/ptrace: assume __WALL if the child is traced") which adds the "automagical" __WALL for debugger. Signed-off-by: Oleg Nesterov Cc: Dmitry Vyukov Cc: Denys Vlasenko Cc: Jan Kratochvil Cc: "Michael Kerrisk (man-pages)" Cc: Pedro Alves Cc: Roland McGrath Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

wait/ptrace: assume __WALL if the child is traced

2016-05-24T00:04:14Z

The following program (simplified version of generated by syzkaller) #include #include #include #include #include void *thread_func(void *arg) { ptrace(PTRACE_TRACEME, 0,0,0); return 0; } int main(void) { pthread_t thread; if (fork()) return 0; while (getppid() != 1) ; pthread_create(&thread, NULL, thread_func, NULL); pthread_join(thread, NULL); return 0; } creates an unreapable zombie if /sbin/init doesn't use __WALL. This is not a kernel bug, at least in a sense that everything works as expected: debugger should reap a traced sub-thread before it can reap the leader, but without __WALL/__WCLONE do_wait() ignores sub-threads. Unfortunately, it seems that /sbin/init in most (all?) distributions doesn't use it and we have to change the kernel to avoid the problem. Note also that most init's use sys_waitid() which doesn't allow __WALL, so the necessary user-space fix is not that trivial. This patch just adds the "ptrace" check into eligible_child(). To some degree this matches the "tsk->ptrace" in exit_notify(), ->exit_signal is mostly ignored when the tracee reports to debugger. Or WSTOPPED, the tracer doesn't need to set this flag to wait for the stopped tracee. This obviously means the user-visible change: __WCLONE and __WALL no longer have any meaning for debugger. And I can only hope that this won't break something, but at least strace/gdb won't suffer. We could make a more conservative change. Say, we can take __WCLONE into account, or !thread_group_leader(). But it would be nice to not complicate these historical/confusing checks. Signed-off-by: Oleg Nesterov Reported-by: Dmitry Vyukov Cc: Denys Vlasenko Cc: Jan Kratochvil Cc: "Michael Kerrisk (man-pages)" Cc: Pedro Alves Cc: Roland McGrath Cc: Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

user/sven/linux.git/kernel/exit.c, branch v4.9.53

sched/autogroup: Do not use autogroup->tg in zombie threads

mm, oom: enforce exit_oom_victim on current task

sched/core: Optimize __schedule()

mm, mempolicy: task->mempolicy must be NULL before dropping final reference

kernel/exit.c: quieten greatest stack depth printk

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

locking/spinlock: Update spin_unlock_wait() users

sched/api: Introduce task_rcu_dereference() and try_get_task_struct()

wait: allow sys_waitid() to accept __WNOTHREAD/__WCLONE/__WALL

wait/ptrace: assume __WALL if the child is traced

wait: allow sys_waitid() to accept WNOTHREAD/WCLONE/__WALL