user/sven/linux.git/kernel/exit.c, branch v4.4.166

kernel/exit.c: avoid undefined behaviour when calling wait4()

2018-05-26T06:48:51Z

commit dd83c161fbcc5d8be637ab159c0de015cbff5ba4 upstream. wait4(-2147483648, 0x20, 0, 0xdd0000) triggers: UBSAN: Undefined behaviour in kernel/exit.c:1651:9 The related calltrace is as follows: negation of -2147483648 cannot be represented in type 'int': CPU: 9 PID: 16482 Comm: zj Tainted: G B ---- ------- 3.10.0-327.53.58.71.x86_64+ #66 Hardware name: Huawei Technologies Co., Ltd. Tecal RH2285 /BC11BTSA , BIOS CTSAV036 04/27/2011 Call Trace: dump_stack+0x19/0x1b ubsan_epilogue+0xd/0x50 __ubsan_handle_negate_overflow+0x109/0x14e SyS_wait4+0x1cb/0x1e0 system_call_fastpath+0x16/0x1b Exclude the overflow to avoid the UBSAN warning. Link: http://lkml.kernel.org/r/1497264618-20212-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhongjiang Cc: Oleg Nesterov Cc: David Rientjes Cc: Aneesh Kumar K.V Cc: Kirill A. Shutemov Cc: Xishi Qiu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

wait/ptrace: assume __WALL if the child is traced

2016-06-08T01:14:35Z

commit bf959931ddb88c4e4366e96dd22e68fa0db9527c upstream. 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: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

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

2015-11-04T02:03:50Z

Pull scheduler changes from Ingo Molnar: "The main changes in this cycle were: - sched/fair load tracking fixes and cleanups (Byungchul Park) - Make load tracking frequency scale invariant (Dietmar Eggemann) - sched/deadline updates (Juri Lelli) - stop machine fixes, cleanups and enhancements for bugs triggered by CPU hotplug stress testing (Oleg Nesterov) - scheduler preemption code rework: remove PREEMPT_ACTIVE and related cleanups (Peter Zijlstra) - Rework the sched_info::run_delay code to fix races (Peter Zijlstra) - Optimize per entity utilization tracking (Peter Zijlstra) - ... misc other fixes, cleanups and smaller updates" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (57 commits) sched: Don't scan all-offline ->cpus_allowed twice if !CONFIG_CPUSETS sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop() sched: Start stopper early stop_machine: Kill cpu_stop_threads->setup() and cpu_stop_unpark() stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark() stop_machine: Change cpu_stop_queue_two_works() to rely on stopper->enabled stop_machine: Introduce __cpu_stop_queue_work() and cpu_stop_queue_two_works() stop_machine: Ensure that a queued callback will be called before cpu_stop_park() sched/x86: Fix typo in __switch_to() comments sched/core: Remove a parameter in the migrate_task_rq() function sched/core: Drop unlikely behind BUG_ON() sched/core: Fix task and run queue sched_info::run_delay inconsistencies sched/numa: Fix task_tick_fair() from disabling numa_balancing sched/core: Add preempt_count invariant check sched/core: More notrace annotations sched/core: Kill PREEMPT_ACTIVE sched/core, sched/x86: Kill thread_info::saved_preempt_count sched/core: Simplify preempt_count tests sched/core: Robustify preemption leak checks sched/core: Stop setting PREEMPT_ACTIVE ...

rcu: Move preemption disabling out of __srcu_read_lock()

2015-10-06T18:15:43Z

Currently, __srcu_read_lock() cannot be invoked from restricted environments because it contains calls to preempt_disable() and preempt_enable(), both of which can invoke lockdep, which is a bad idea in some restricted execution modes. This commit therefore moves the preempt_disable() and preempt_enable() from __srcu_read_lock() to srcu_read_lock(). It also inserts the preempt_disable() and preempt_enable() around the call to __srcu_read_lock() in do_exit(). Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

sched/core: Robustify preemption leak checks

2015-10-06T15:08:17Z

When we warn about a preempt_count leak; reset the preempt_count to the known good value such that the problem does not ripple forward. This is most important on x86 which has a per cpu preempt_count that is not saved/restored (after this series). So if you schedule with an invalid (!2*PREEMPT_DISABLE_OFFSET) preempt_count the next task is messed up too. Enforcing this invariant limits the borkage to just the one task. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Frederic Weisbecker Reviewed-by: Thomas Gleixner Reviewed-by: Steven Rostedt Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

kernel: exit: fix typo in comment

2015-08-07T11:59:49Z

s,critiera,criteria, While at it, add a comma, because it makes sense grammatically. Signed-off-by: Frans Klaver Signed-off-by: Jiri Kosina

exit,stats: /* obey this comment */

2015-06-26T00:00:43Z

There is a helpful comment in do_exit() that states we sync the mm's RSS info before statistics gathering. The function that does the statistics gathering is called right above that comment. Change the code to obey the comment. Signed-off-by: Rik van Riel Cc: Oleg Nesterov Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: oom_kill: clean up victim marking and exiting interfaces

2015-06-25T00:49:43Z

Rename unmark_oom_victim() to exit_oom_victim(). Marking and unmarking are related in functionality, but the interface is not symmetrical at all: one is an internal OOM killer function used during the killing, the other is for an OOM victim to signal its own death on exit later on. This has locking implications, see follow-up changes. While at it, rename mark_tsk_oom_victim() to mark_oom_victim(), which is easier on the eye. Signed-off-by: Johannes Weiner Acked-by: David Rientjes Acked-by: Michal Hocko Cc: Tetsuo Handa Cc: Andrea Arcangeli Cc: Dave Chinner Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Remove execution domain support

2015-04-12T18:58:24Z

All users of exec_domain are gone, now we can get rid of that abandoned feature. To not break existing userspace we keep a dummy /proc/execdomains file which will always contain "0-0 Linux [kernel]". Signed-off-by: Richard Weinberger

oom, PM: make OOM detection in the freezer path raceless

2015-02-12T01:06:03Z

Commit 5695be142e20 ("OOM, PM: OOM killed task shouldn't escape PM suspend") has left a race window when OOM killer manages to note_oom_kill after freeze_processes checks the counter. The race window is quite small and really unlikely and partial solution deemed sufficient at the time of submission. Tejun wasn't happy about this partial solution though and insisted on a full solution. That requires the full OOM and freezer's task freezing exclusion, though. This is done by this patch which introduces oom_sem RW lock and turns oom_killer_disable() into a full OOM barrier. oom_killer_disabled check is moved from the allocation path to the OOM level and we take oom_sem for reading for both the check and the whole OOM invocation. oom_killer_disable() takes oom_sem for writing so it waits for all currently running OOM killer invocations. Then it disable all the further OOMs by setting oom_killer_disabled and checks for any oom victims. Victims are counted via mark_tsk_oom_victim resp. unmark_oom_victim. The last victim wakes up all waiters enqueued by oom_killer_disable(). Therefore this function acts as the full OOM barrier. The page fault path is covered now as well although it was assumed to be safe before. As per Tejun, "We used to have freezing points deep in file system code which may be reacheable from page fault." so it would be better and more robust to not rely on freezing points here. Same applies to the memcg OOM killer. out_of_memory tells the caller whether the OOM was allowed to trigger and the callers are supposed to handle the situation. The page allocation path simply fails the allocation same as before. The page fault path will retry the fault (more on that later) and Sysrq OOM trigger will simply complain to the log. Normally there wouldn't be any unfrozen user tasks after try_to_freeze_tasks so the function will not block. But if there was an OOM killer racing with try_to_freeze_tasks and the OOM victim didn't finish yet then we have to wait for it. This should complete in a finite time, though, because - the victim cannot loop in the page fault handler (it would die on the way out from the exception) - it cannot loop in the page allocator because all the further allocation would fail and __GFP_NOFAIL allocations are not acceptable at this stage - it shouldn't be blocked on any locks held by frozen tasks (try_to_freeze expects lockless context) and kernel threads and work queues are not frozen yet Signed-off-by: Michal Hocko Suggested-by: Tejun Heo Cc: David Rientjes Cc: Johannes Weiner Cc: Oleg Nesterov Cc: Cong Wang Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds