From 7551a1a2a11f307f74ee5a1654843ef990b69d02 Mon Sep 17 00:00:00 2001 From: Pavankumar Kondeti Date: Fri, 16 Apr 2021 15:21:14 +0530 Subject: [PATCH] ANDROID: cgroup: Add android_rvh_cgroup_force_kthread_migration In Android GKI, CONFIG_FAIR_GROUP_SCHED is enabled [1] to help prioritize important work. Given that CPU shares of root cgroup can't be changed, leaving the tasks inside root cgroup will give them higher share compared to the other tasks inside important cgroups. This is mitigated by moving all tasks inside root cgroup to a different cgroup after Android is booted. However, there are many kernel tasks stuck in the root cgroup after the boot. It is possible to relax kernel threads and kworkers migrations under certain scenarios. However the patch [2] posted at upstream is not accepted. Hence add a restricted vendor hook to notify modules when a kernel thread is requested for cgroup migration. The modules can relax the restrictions forced by the kernel and allow the cgroup migration. [1] https://android.googlesource.com/kernel/common/+/f08f049de11c15a4251cb1db08cf0bee20bd9b59 [2] https://lore.kernel.org/lkml/1617714261-18111-1-git-send-email-pkondeti@codeaurora.org Bug: 184594949 Change-Id: I445a170ba797c8bece3b4b59b7a42cdd85438f1f Signed-off-by: Pavankumar Kondeti [quic_dickey@quicinc.com: port to android-mainline kernel] Signed-off-by: Stephen Dickey --- drivers/android/vendor_hooks.c | 1 + include/trace/hooks/cgroup.h | 4 ++++ kernel/cgroup/cgroup-internal.h | 3 ++- kernel/cgroup/cgroup-v1.c | 2 +- kernel/cgroup/cgroup.c | 11 ++++++++--- 5 files changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/android/vendor_hooks.c b/drivers/android/vendor_hooks.c index 36616a30c55b..1f31007f8c65 100644 --- a/drivers/android/vendor_hooks.c +++ b/drivers/android/vendor_hooks.c @@ -136,6 +136,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_update_sysfs); EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_send_command); EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_compl_command); EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_cgroup_set_task); +EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_cgroup_force_kthread_migration); EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_syscall_prctl_finished); EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_send_uic_command); EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_ufs_send_tm_command); diff --git a/include/trace/hooks/cgroup.h b/include/trace/hooks/cgroup.h index a50e6abc55ee..b824197118f9 100644 --- a/include/trace/hooks/cgroup.h +++ b/include/trace/hooks/cgroup.h @@ -23,6 +23,10 @@ DECLARE_HOOK(android_vh_cgroup_attach, TP_PROTO(struct cgroup_subsys *ss, struct cgroup_taskset *tset), TP_ARGS(ss, tset)); +DECLARE_RESTRICTED_HOOK(android_rvh_cgroup_force_kthread_migration, + TP_PROTO(struct task_struct *tsk, struct cgroup *dst_cgrp, bool *force_migration), + TP_ARGS(tsk, dst_cgrp, force_migration), 1); + DECLARE_RESTRICTED_HOOK(android_rvh_cpuset_fork, TP_PROTO(struct task_struct *p, bool *inherit_cpus), TP_ARGS(p, inherit_cpus), 1); diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index 367b0a42ada9..892b770067b5 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -251,7 +251,8 @@ int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader, void cgroup_attach_lock(bool lock_threadgroup); void cgroup_attach_unlock(bool lock_threadgroup); struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup, - bool *locked) + bool *locked, + struct cgroup *dst_cgrp); __acquires(&cgroup_threadgroup_rwsem); void cgroup_procs_write_finish(struct task_struct *task, bool locked) __releases(&cgroup_threadgroup_rwsem); diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index c6822bf6c918..fed5bf717ce1 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -501,7 +501,7 @@ static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of, if (!cgrp) return -ENODEV; - task = cgroup_procs_write_start(buf, threadgroup, &locked); + task = cgroup_procs_write_start(buf, threadgroup, &locked, cgrp); ret = PTR_ERR_OR_ZERO(task); if (ret) goto out_unlock; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index c827832ff7a2..7ccbfa771e0c 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2920,10 +2920,12 @@ int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader, } struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup, - bool *threadgroup_locked) + bool *threadgroup_locked, + struct cgroup *dst_cgrp) { struct task_struct *tsk; pid_t pid; + bool force_migration = false; if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) return ERR_PTR(-EINVAL); @@ -2954,13 +2956,16 @@ struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup, if (threadgroup) tsk = tsk->group_leader; + if (tsk->flags & PF_KTHREAD) + trace_android_rvh_cgroup_force_kthread_migration(tsk, dst_cgrp, &force_migration); + /* * kthreads may acquire PF_NO_SETAFFINITY during initialization. * If userland migrates such a kthread to a non-root cgroup, it can * become trapped in a cpuset, or RT kthread may be born in a * cgroup with no rt_runtime allocated. Just say no. */ - if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) { + if (!force_migration && (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY))) { tsk = ERR_PTR(-EINVAL); goto out_unlock_threadgroup; } @@ -5147,7 +5152,7 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, if (!dst_cgrp) return -ENODEV; - task = cgroup_procs_write_start(buf, threadgroup, &threadgroup_locked); + task = cgroup_procs_write_start(buf, threadgroup, &threadgroup_locked, dst_cgrp); ret = PTR_ERR_OR_ZERO(task); if (ret) goto out_unlock;