user/sven/linux.git/include/linux/sched, branch v5.0.19

ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK

2019-05-04T07:21:23Z

[ Upstream commit fcfc2aa0185f4a731d05a21e9f359968fdfd02e7 ] There are a few system calls (pselect, ppoll, etc) which replace a task sigmask while they are running in a kernel-space When a task calls one of these syscalls, the kernel saves a current sigmask in task->saved_sigmask and sets a syscall sigmask. On syscall-exit-stop, ptrace traps a task before restoring the saved_sigmask, so PTRACE_GETSIGMASK returns the syscall sigmask and PTRACE_SETSIGMASK does nothing, because its sigmask is replaced by saved_sigmask, when the task returns to user-space. This patch fixes this problem. PTRACE_GETSIGMASK returns saved_sigmask if it's set. PTRACE_SETSIGMASK drops the TIF_RESTORE_SIGMASK flag. Link: http://lkml.kernel.org/r/20181120060616.6043-1-avagin@gmail.com Fixes: 29000caecbe8 ("ptrace: add ability to get/set signal-blocked mask") Signed-off-by: Andrei Vagin Acked-by: Oleg Nesterov Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin (Microsoft)

coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping

2019-04-27T07:37:41Z

commit 04f5866e41fb70690e28397487d8bd8eea7d712a upstream. The core dumping code has always run without holding the mmap_sem for writing, despite that is the only way to ensure that the entire vma layout will not change from under it. Only using some signal serialization on the processes belonging to the mm is not nearly enough. This was pointed out earlier. For example in Hugh's post from Jul 2017: https://lkml.kernel.org/r/alpine.LSU.2.11.1707191716030.2055@eggly.anvils "Not strictly relevant here, but a related note: I was very surprised to discover, only quite recently, how handle_mm_fault() may be called without down_read(mmap_sem) - when core dumping. That seems a misguided optimization to me, which would also be nice to correct" In particular because the growsdown and growsup can move the vm_start/vm_end the various loops the core dump does around the vma will not be consistent if page faults can happen concurrently. Pretty much all users calling mmget_not_zero()/get_task_mm() and then taking the mmap_sem had the potential to introduce unexpected side effects in the core dumping code. Adding mmap_sem for writing around the ->core_dump invocation is a viable long term fix, but it requires removing all copy user and page faults and to replace them with get_dump_page() for all binary formats which is not suitable as a short term fix. For the time being this solution manually covers the places that can confuse the core dump either by altering the vma layout or the vma flags while it runs. Once ->core_dump runs under mmap_sem for writing the function mmget_still_valid() can be dropped. Allowing mmap_sem protected sections to run in parallel with the coredump provides some minor parallelism advantage to the swapoff code (which seems to be safe enough by never mangling any vma field and can keep doing swapins in parallel to the core dumping) and to some other corner case. In order to facilitate the backporting I added "Fixes: 86039bd3b4e6" however the side effect of this same race condition in /proc/pid/mem should be reproducible since before 2.6.12-rc2 so I couldn't add any other "Fixes:" because there's no hash beyond the git genesis commit. Because find_extend_vma() is the only location outside of the process context that could modify the "mm" structures under mmap_sem for reading, by adding the mmget_still_valid() check to it, all other cases that take the mmap_sem for reading don't need the new check after mmget_not_zero()/get_task_mm(). The expand_stack() in page fault context also doesn't need the new check, because all tasks under core dumping are frozen. Link: http://lkml.kernel.org/r/20190325224949.11068-1-aarcange@redhat.com Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") Signed-off-by: Andrea Arcangeli Reported-by: Jann Horn Suggested-by: Oleg Nesterov Acked-by: Peter Xu Reviewed-by: Mike Rapoport Reviewed-by: Oleg Nesterov Reviewed-by: Jann Horn Acked-by: Jason Gunthorpe Acked-by: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

sched/topology: Fix percpu data types in struct sd_data & struct s_data

2019-04-05T20:34:40Z

[ Upstream commit 99687cdbb3f6c8e32bcc7f37496e811f30460e48 ] The percpu members of struct sd_data and s_data are declared as: struct ... ** __percpu member; So their type is: __percpu pointer to pointer to struct ... But looking at how they're used, their type should be: pointer to __percpu pointer to struct ... and they should thus be declared as: struct ... * __percpu *member; So fix the placement of '__percpu' in the definition of these structures. This addresses a bunch of Sparse's warnings like: warning: incorrect type in initializer (different address spaces) expected void const [noderef] *__vpp_verify got struct sched_domain ** Signed-off-by: Luc Van Oostenryck Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190118144936.79158-1-luc.vanoostenryck@gmail.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin

oom, oom_reaper: do not enqueue same task twice

2019-02-01T23:46:23Z

Arkadiusz reported that enabling memcg's group oom killing causes strange memcg statistics where there is no task in a memcg despite the number of tasks in that memcg is not 0. It turned out that there is a bug in wake_oom_reaper() which allows enqueuing same task twice which makes impossible to decrease the number of tasks in that memcg due to a refcount leak. This bug existed since the OOM reaper became invokable from task_will_free_mem(current) path in out_of_memory() in Linux 4.7, T1@P1 |T2@P1 |T3@P1 |OOM reaper ----------+----------+----------+------------ # Processing an OOM victim in a different memcg domain. try_charge() mem_cgroup_out_of_memory() mutex_lock(&oom_lock) try_charge() mem_cgroup_out_of_memory() mutex_lock(&oom_lock) try_charge() mem_cgroup_out_of_memory() mutex_lock(&oom_lock) out_of_memory() oom_kill_process(P1) do_send_sig_info(SIGKILL, @P1) mark_oom_victim(T1@P1) wake_oom_reaper(T1@P1) # T1@P1 is enqueued. mutex_unlock(&oom_lock) out_of_memory() mark_oom_victim(T2@P1) wake_oom_reaper(T2@P1) # T2@P1 is enqueued. mutex_unlock(&oom_lock) out_of_memory() mark_oom_victim(T1@P1) wake_oom_reaper(T1@P1) # T1@P1 is enqueued again due to oom_reaper_list == T2@P1 && T1@P1->oom_reaper_list == NULL. mutex_unlock(&oom_lock) # Completed processing an OOM victim in a different memcg domain. spin_lock(&oom_reaper_lock) # T1P1 is dequeued. spin_unlock(&oom_reaper_lock) but memcg's group oom killing made it easier to trigger this bug by calling wake_oom_reaper() on the same task from one out_of_memory() request. Fix this bug using an approach used by commit 855b018325737f76 ("oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task"). As a side effect of this patch, this patch also avoids enqueuing multiple threads sharing memory via task_will_free_mem(current) path. Link: http://lkml.kernel.org/r/e865a044-2c10-9858-f4ef-254bc71d6cc2@i-love.sakura.ne.jp Link: http://lkml.kernel.org/r/5ee34fc6-1485-34f8-8790-903ddabaa809@i-love.sakura.ne.jp Fixes: af8e15cc85a25315 ("oom, oom_reaper: do not enqueue task if it is on the oom_reaper_list head") Signed-off-by: Tetsuo Handa Reported-by: Arkadiusz Miskiewicz Tested-by: Arkadiusz Miskiewicz Acked-by: Michal Hocko Acked-by: Roman Gushchin Cc: Tejun Heo Cc: Aleksa Sarai Cc: Jay Kamat Cc: Johannes Weiner Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched/wake_q: Document wake_q_add()

2019-01-21T10:15:36Z

The only guarantee provided by wake_q_add() is that a wakeup will happen after it, it does _NOT_ guarantee the wakeup will be delayed until the matching wake_up_q(). If wake_q_add() fails the cmpxchg() a concurrent wakeup is pending and that can happen at any time after the cmpxchg(). This means we should not rely on the wakeup happening at wake_q_up(), but should be ready for wake_q_add() to issue the wakeup. The delay; if provided (most likely); should only result in more efficient behaviour. Reported-by: Yongji Xie Signed-off-by: Peter Zijlstra (Intel) Cc: Davidlohr Bueso Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Waiman Long Cc: Will Deacon Signed-off-by: Ingo Molnar

fork: fix some -Wmissing-prototypes warnings

2019-01-04T21:13:47Z

We get a warning when building kernel with W=1: kernel/fork.c:167:13: warning: no previous prototype for `arch_release_thread_stack' [-Wmissing-prototypes] kernel/fork.c:779:13: warning: no previous prototype for `fork_init' [-Wmissing-prototypes] Add the missing declaration in head file to fix this. Also, remove arch_release_thread_stack() completely because no arch seems to implement it since bb9d81264 (arch: remove tile port). Link: http://lkml.kernel.org/r/1542170087-23645-1-git-send-email-wang.yi59@zte.com.cn Signed-off-by: Yi Wang Acked-by: Michal Hocko Acked-by: Mike Rapoport Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sched/cpufreq: Prepare schedutil for Energy Aware Scheduling

2018-12-11T14:16:58Z

Schedutil requests frequency by aggregating utilization signals from the scheduler (CFS, RT, DL, IRQ) and applying a 25% margin on top of them. Since Energy Aware Scheduling (EAS) needs to be able to predict the frequency requests, it needs to forecast the decisions made by the governor. In order to prepare the introduction of EAS, introduce schedutil_freq_util() to centralize the aforementioned signal aggregation and make it available to both schedutil and EAS. Since frequency selection and energy estimation still need to deal with RT and DL signals slightly differently, schedutil_freq_util() is called with a different 'type' parameter in those two contexts, and returns an aggregated utilization signal accordingly. While at it, introduce the map_util_freq() function which is designed to make schedutil's 25% margin usable easily for both sugov and EAS. As EAS will be able to predict schedutil's frequency requests more accurately than any other governor by design, it'd be sensible to make sure EAS cannot be used without schedutil. This will be done later, once EAS has actually been introduced. Suggested-by: Peter Zijlstra Signed-off-by: Quentin Perret Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Thomas Gleixner Cc: adharmap@codeaurora.org Cc: chris.redpath@arm.com Cc: currojerez@riseup.net Cc: dietmar.eggemann@arm.com Cc: edubezval@gmail.com Cc: gregkh@linuxfoundation.org Cc: javi.merino@kernel.org Cc: joel@joelfernandes.org Cc: juri.lelli@redhat.com Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: pkondeti@codeaurora.org Cc: rjw@rjwysocki.net Cc: skannan@codeaurora.org Cc: smuckle@google.com Cc: srinivas.pandruvada@linux.intel.com Cc: thara.gopinath@linaro.org Cc: tkjos@google.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Cc: viresh.kumar@linaro.org Link: https://lkml.kernel.org/r/20181203095628.11858-3-quentin.perret@arm.com Signed-off-by: Ingo Molnar

sched/topology: Relocate arch_scale_cpu_capacity() to the internal header

2018-12-11T14:16:58Z

By default, arch_scale_cpu_capacity() is only visible from within the kernel/sched folder. Relocate it to include/linux/sched/topology.h to make it visible to other clients needing to know about the capacity of CPUs, such as the Energy Model framework. This also shrinks the public header. Signed-off-by: Quentin Perret Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: adharmap@codeaurora.org Cc: chris.redpath@arm.com Cc: currojerez@riseup.net Cc: dietmar.eggemann@arm.com Cc: edubezval@gmail.com Cc: gregkh@linuxfoundation.org Cc: javi.merino@kernel.org Cc: joel@joelfernandes.org Cc: juri.lelli@redhat.com Cc: morten.rasmussen@arm.com Cc: patrick.bellasi@arm.com Cc: pkondeti@codeaurora.org Cc: rjw@rjwysocki.net Cc: skannan@codeaurora.org Cc: smuckle@google.com Cc: srinivas.pandruvada@linux.intel.com Cc: thara.gopinath@linaro.org Cc: tkjos@google.com Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Cc: viresh.kumar@linaro.org Link: https://lkml.kernel.org/r/20181203095628.11858-2-quentin.perret@arm.com Signed-off-by: Ingo Molnar

sched/topology: Remove the ::smt_gain field from 'struct sched_domain'

2018-12-11T14:16:57Z

::smt_gain is used to compute the capacity of CPUs of a SMT core with the constraint 1 < ::smt_gain < 2 in order to be able to compute number of CPUs per core. The field has_free_capacity of struct numa_stat, which was the last user of this computation of number of CPUs per core, has been removed by: 2d4056fafa19 ("sched/numa: Remove numa_has_capacity()") We can now remove this constraint on core capacity and use the defautl value SCHED_CAPACITY_SCALE for SMT CPUs. With this remove, SCHED_CAPACITY_SCALE becomes the maximum compute capacity of CPUs on every systems. This should help to simplify some code and remove fields like rd->max_cpu_capacity Furthermore, arch_scale_cpu_capacity() is used with a NULL sd in several other places in the code when it wants the capacity of a CPUs to scale some metrics like in pelt, deadline or schedutil. In case on SMT, the value returned is not the capacity of SMT CPUs but default SCHED_CAPACITY_SCALE. So remove it. Signed-off-by: Vincent Guittot Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1535548752-4434-4-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar

sched: Fix various typos in comments

2018-12-03T10:55:42Z

Go over the scheduler source code and fix common typos in comments - and a typo in an actual variable name. No change in functionality intended. Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar