From 49de4996f146c8584c0033af8b985039c97e2b66 Mon Sep 17 00:00:00 2001 From: Xuewei Zhang Date: Thu, 3 Oct 2019 17:12:43 -0700 Subject: sched/fair: Scale bandwidth quota and period without losing quota/period ratio precision commit 4929a4e6faa0f13289a67cae98139e727f0d4a97 upstream. The quota/period ratio is used to ensure a child task group won't get more bandwidth than the parent task group, and is calculated as: normalized_cfs_quota() = [(quota_us << 20) / period_us] If the quota/period ratio was changed during this scaling due to precision loss, it will cause inconsistency between parent and child task groups. See below example: A userspace container manager (kubelet) does three operations: 1) Create a parent cgroup, set quota to 1,000us and period to 10,000us. 2) Create a few children cgroups. 3) Set quota to 1,000us and period to 10,000us on a child cgroup. These operations are expected to succeed. However, if the scaling of 147/128 happens before step 3, quota and period of the parent cgroup will be changed: new_quota: 1148437ns, 1148us new_period: 11484375ns, 11484us And when step 3 comes in, the ratio of the child cgroup will be 104857, which will be larger than the parent cgroup ratio (104821), and will fail. Scaling them by a factor of 2 will fix the problem. Tested-by: Phil Auld Signed-off-by: Xuewei Zhang Signed-off-by: Peter Zijlstra (Intel) Acked-by: Phil Auld Cc: Anton Blanchard Cc: Ben Segall Cc: Dietmar Eggemann Cc: Juri Lelli Cc: Linus Torvalds Cc: Mel Gorman Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Vincent Guittot Fixes: 2e8e19226398 ("sched/fair: Limit sched_cfs_period_timer() loop to avoid hard lockup") Link: https://lkml.kernel.org/r/20191004001243.140897-1-xueweiz@google.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched/fair.c | 36 ++++++++++++++++++++++-------------- 1 file changed, 22 insertions(+), 14 deletions(-) (limited to 'kernel') diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d012681fb1ab..b42d2b8b283e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4055,20 +4055,28 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) if (++count > 3) { u64 new, old = ktime_to_ns(cfs_b->period); - new = (old * 147) / 128; /* ~115% */ - new = min(new, max_cfs_quota_period); - - cfs_b->period = ns_to_ktime(new); - - /* since max is 1s, this is limited to 1e9^2, which fits in u64 */ - cfs_b->quota *= new; - cfs_b->quota = div64_u64(cfs_b->quota, old); - - pr_warn_ratelimited( - "cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us %lld, cfs_quota_us = %lld)\n", - smp_processor_id(), - div_u64(new, NSEC_PER_USEC), - div_u64(cfs_b->quota, NSEC_PER_USEC)); + /* + * Grow period by a factor of 2 to avoid losing precision. + * Precision loss in the quota/period ratio can cause __cfs_schedulable + * to fail. + */ + new = old * 2; + if (new < max_cfs_quota_period) { + cfs_b->period = ns_to_ktime(new); + cfs_b->quota *= 2; + + pr_warn_ratelimited( + "cfs_period_timer[cpu%d]: period too short, scaling up (new cfs_period_us = %lld, cfs_quota_us = %lld)\n", + smp_processor_id(), + div_u64(new, NSEC_PER_USEC), + div_u64(cfs_b->quota, NSEC_PER_USEC)); + } else { + pr_warn_ratelimited( + "cfs_period_timer[cpu%d]: period too short, but cannot scale up without losing precision (cfs_period_us = %lld, cfs_quota_us = %lld)\n", + smp_processor_id(), + div_u64(old, NSEC_PER_USEC), + div_u64(cfs_b->quota, NSEC_PER_USEC)); + } /* reset count so we don't come right back in here */ count = 0; -- cgit v1.2.3 From 1354c2fa639636e3b83a736fb29eb449477c64f9 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 13 Sep 2016 14:29:24 -0700 Subject: sched/core: Allow putting thread_info into task_struct commit c65eacbe290b8141554c71b2c94489e73ade8c8d upstream. If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT, then thread_info is defined as a single 'u32 flags' and is the first entry of task_struct. thread_info::task is removed (it serves no purpose if thread_info is embedded in task_struct), and thread_info::cpu gets its own slot in task_struct. This is heavily based on a patch written by Linus. Originally-from: Linus Torvalds Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: zhangyi (F) Signed-off-by: Greg Kroah-Hartman --- kernel/sched/sched.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel') diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 8b96df04ba78..8afd9d62c56e 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -978,7 +978,11 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu) * per-task data have been completed by this moment. */ smp_wmb(); +#ifdef CONFIG_THREAD_INFO_IN_TASK + p->cpu = cpu; +#else task_thread_info(p)->cpu = cpu; +#endif p->wake_cpu = cpu; #endif } -- cgit v1.2.3 From 8d68d0346f441c293268a0cbd91807a9c2fd5dc4 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 18 Sep 2019 18:43:40 -0700 Subject: workqueue: Fix spurious sanity check failures in destroy_workqueue() commit def98c84b6cdf2eeea19ec5736e90e316df5206b upstream. Before actually destrying a workqueue, destroy_workqueue() checks whether it's actually idle. If it isn't, it prints out a bunch of warning messages and leaves the workqueue dangling. It unfortunately has a couple issues. * Mayday list queueing increments pwq's refcnts which gets detected as busy and fails the sanity checks. However, because mayday list queueing is asynchronous, this condition can happen without any actual work items left in the workqueue. * Sanity check failure leaves the sysfs interface behind too which can lead to init failure of newer instances of the workqueue. This patch fixes the above two by * If a workqueue has a rescuer, disable and kill the rescuer before sanity checks. Disabling and killing is guaranteed to flush the existing mayday list. * Remove sysfs interface before sanity checks. Signed-off-by: Tejun Heo Reported-by: Marcin Pawlowski Reported-by: "Williams, Gerald S" Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- kernel/workqueue.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index d8a2084b88db..42225eb52758 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3949,9 +3949,28 @@ void destroy_workqueue(struct workqueue_struct *wq) struct pool_workqueue *pwq; int node; + /* + * Remove it from sysfs first so that sanity check failure doesn't + * lead to sysfs name conflicts. + */ + workqueue_sysfs_unregister(wq); + /* drain it before proceeding with destruction */ drain_workqueue(wq); + /* kill rescuer, if sanity checks fail, leave it w/o rescuer */ + if (wq->rescuer) { + struct worker *rescuer = wq->rescuer; + + /* this prevents new queueing */ + spin_lock_irq(&wq_mayday_lock); + wq->rescuer = NULL; + spin_unlock_irq(&wq_mayday_lock); + + /* rescuer will empty maydays list before exiting */ + kthread_stop(rescuer->task); + } + /* sanity checks */ mutex_lock(&wq->mutex); for_each_pwq(pwq, wq) { @@ -3981,11 +4000,6 @@ void destroy_workqueue(struct workqueue_struct *wq) list_del_rcu(&wq->list); mutex_unlock(&wq_pool_mutex); - workqueue_sysfs_unregister(wq); - - if (wq->rescuer) - kthread_stop(wq->rescuer->task); - if (!(wq->flags & WQ_UNBOUND)) { /* * The base ref is never dropped on per-cpu pwqs. Directly -- cgit v1.2.3 From 182589e427191a543823e8fdc02653636ac04d52 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 25 Sep 2019 06:59:15 -0700 Subject: workqueue: Fix pwq ref leak in rescuer_thread() commit e66b39af00f426b3356b96433d620cb3367ba1ff upstream. 008847f66c3 ("workqueue: allow rescuer thread to do more work.") made the rescuer worker requeue the pwq immediately if there may be more work items which need rescuing instead of waiting for the next mayday timer expiration. Unfortunately, it doesn't check whether the pwq is already on the mayday list and unconditionally gets the ref and moves it onto the list. This doesn't corrupt the list but creates an additional reference to the pwq. It got queued twice but will only be removed once. This leak later can trigger pwq refcnt warning on workqueue destruction and prevent freeing of the workqueue. Signed-off-by: Tejun Heo Cc: "Williams, Gerald S" Cc: NeilBrown Cc: stable@vger.kernel.org # v3.19+ Signed-off-by: Greg Kroah-Hartman --- kernel/workqueue.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 42225eb52758..da56a36830b7 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -2308,8 +2308,14 @@ repeat: */ if (need_to_create_worker(pool)) { spin_lock(&wq_mayday_lock); - get_pwq(pwq); - list_move_tail(&pwq->mayday_node, &wq->maydays); + /* + * Queue iff we aren't racing destruction + * and somebody else hasn't queued it already. + */ + if (wq->rescuer && list_empty(&pwq->mayday_node)) { + get_pwq(pwq); + list_add_tail(&pwq->mayday_node, &wq->maydays); + } spin_unlock(&wq_mayday_lock); } } @@ -4276,7 +4282,8 @@ static void show_pwq(struct pool_workqueue *pwq) pr_info(" pwq %d:", pool->id); pr_cont_pool_info(pool); - pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active, + pr_cont(" active=%d/%d refcnt=%d%s\n", + pwq->nr_active, pwq->max_active, pwq->refcnt, !list_empty(&pwq->mayday_node) ? " MAYDAY" : ""); hash_for_each(pool->busy_hash, bkt, worker, hentry) { -- cgit v1.2.3 From bd0c9ceb8ab93fccb5f00590e0cafd3662a948ed Mon Sep 17 00:00:00 2001 From: Aleksa Sarai Date: Thu, 17 Oct 2019 02:50:01 +1100 Subject: cgroup: pids: use atomic64_t for pids->limit commit a713af394cf382a30dd28a1015cbe572f1b9ca75 upstream. Because pids->limit can be changed concurrently (but we don't want to take a lock because it would be needlessly expensive), use atomic64_ts instead. Fixes: commit 49b786ea146f ("cgroup: implement the PIDs subsystem") Cc: stable@vger.kernel.org # v4.3+ Signed-off-by: Aleksa Sarai Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup_pids.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/cgroup_pids.c b/kernel/cgroup_pids.c index b50d5a167fda..ea8cb03dbf72 100644 --- a/kernel/cgroup_pids.c +++ b/kernel/cgroup_pids.c @@ -48,7 +48,7 @@ struct pids_cgroup { * %PIDS_MAX = (%PID_MAX_LIMIT + 1). */ atomic64_t counter; - int64_t limit; + atomic64_t limit; }; static struct pids_cgroup *css_pids(struct cgroup_subsys_state *css) @@ -70,8 +70,8 @@ pids_css_alloc(struct cgroup_subsys_state *parent) if (!pids) return ERR_PTR(-ENOMEM); - pids->limit = PIDS_MAX; atomic64_set(&pids->counter, 0); + atomic64_set(&pids->limit, PIDS_MAX); return &pids->css; } @@ -142,13 +142,14 @@ static int pids_try_charge(struct pids_cgroup *pids, int num) for (p = pids; parent_pids(p); p = parent_pids(p)) { int64_t new = atomic64_add_return(num, &p->counter); + int64_t limit = atomic64_read(&p->limit); /* * Since new is capped to the maximum number of pid_t, if * p->limit is %PIDS_MAX then we know that this test will never * fail. */ - if (new > p->limit) + if (new > limit) goto revert; } @@ -262,7 +263,7 @@ set_limit: * Limit updates don't need to be mutex'd, since it isn't * critical that any racing fork()s follow the new limit. */ - pids->limit = limit; + atomic64_set(&pids->limit, limit); return nbytes; } @@ -270,7 +271,7 @@ static int pids_max_show(struct seq_file *sf, void *v) { struct cgroup_subsys_state *css = seq_css(sf); struct pids_cgroup *pids = css_pids(css); - int64_t limit = pids->limit; + int64_t limit = atomic64_read(&pids->limit); if (limit >= PIDS_MAX) seq_printf(sf, "%s\n", PIDS_MAX_STR); -- cgit v1.2.3 From af99d946e62911801fea31bcec3957f8944fcc8c Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 20 Sep 2019 13:39:57 -0700 Subject: workqueue: Fix missing kfree(rescuer) in destroy_workqueue() commit 8efe1223d73c218ce7e8b2e0e9aadb974b582d7f upstream. Signed-off-by: Tejun Heo Reported-by: Qian Cai Fixes: def98c84b6cd ("workqueue: Fix spurious sanity check failures in destroy_workqueue()") Cc: Nobuhiro Iwamatsu Signed-off-by: Greg Kroah-Hartman --- kernel/workqueue.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index da56a36830b7..3fb2d45c0b42 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3975,6 +3975,7 @@ void destroy_workqueue(struct workqueue_struct *wq) /* rescuer will empty maydays list before exiting */ kthread_stop(rescuer->task); + kfree(rescuer); } /* sanity checks */ -- cgit v1.2.3 From 575a2dbce0b2c8e489c0566527d99ebc54d35d54 Mon Sep 17 00:00:00 2001 From: Konstantin Khorenko Date: Wed, 13 Nov 2019 12:29:50 +0300 Subject: kernel/module.c: wakeup processes in module_wq on module unload [ Upstream commit 5d603311615f612320bb77bd2a82553ef1ced5b7 ] Fix the race between load and unload a kernel module. sys_delete_module() try_stop_module() mod->state = _GOING add_unformed_module() old = find_module_all() (old->state == _GOING => wait_event_interruptible()) During pre-condition finished_loading() rets 0 schedule() (never gets waken up later) free_module() mod->state = _UNFORMED list_del_rcu(&mod->list) (dels mod from "modules" list) return The race above leads to modprobe hanging forever on loading a module. Error paths on loading module call wake_up_all(&module_wq) after freeing module, so let's do the same on straight module unload. Fixes: 6e6de3dee51a ("kernel/module.c: Only return -EEXIST for modules that have finished loading") Reviewed-by: Prarit Bhargava Signed-off-by: Konstantin Khorenko Signed-off-by: Jessica Yu Signed-off-by: Sasha Levin --- kernel/module.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/module.c b/kernel/module.c index b940b2825b7b..2f695b6e1a3e 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1014,6 +1014,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user, strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module)); free_module(mod); + /* someone could wait for the module in add_unformed_module() */ + wake_up_all(&module_wq); return 0; out: mutex_unlock(&module_mutex); -- cgit v1.2.3