diff options
Diffstat (limited to 'kernel/cgroup/cgroup.c')
| -rw-r--r-- | kernel/cgroup/cgroup.c | 43 |
1 files changed, 36 insertions, 7 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 9ce24d5cf2d5..7d023d42a6a5 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1305,6 +1305,20 @@ struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) return root_cgrp->root; } +void cgroup_favor_dynmods(struct cgroup_root *root, bool favor) +{ + bool favoring = root->flags & CGRP_ROOT_FAVOR_DYNMODS; + + /* see the comment above CGRP_ROOT_FAVOR_DYNMODS definition */ + if (favor && !favoring) { + rcu_sync_enter(&cgroup_threadgroup_rwsem.rss); + root->flags |= CGRP_ROOT_FAVOR_DYNMODS; + } else if (!favor && favoring) { + rcu_sync_exit(&cgroup_threadgroup_rwsem.rss); + root->flags &= ~CGRP_ROOT_FAVOR_DYNMODS; + } +} + static int cgroup_init_root_id(struct cgroup_root *root) { int id; @@ -1365,6 +1379,7 @@ static void cgroup_destroy_root(struct cgroup_root *root) cgroup_root_count--; } + cgroup_favor_dynmods(root, false); cgroup_exit_root_id(root); mutex_unlock(&cgroup_mutex); @@ -1858,6 +1873,7 @@ int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node, enum cgroup2_param { Opt_nsdelegate, Opt_nonsdelegate, + Opt_favordynmods, Opt_nofavordynmods, Opt_memory_localevents, Opt_memory_nolocalevents, Opt_memory_recursiveprot, Opt_memory_norecursiveprot, nr__cgroup2_params @@ -1866,6 +1882,8 @@ enum cgroup2_param { static const struct fs_parameter_spec cgroup2_fs_parameters[] = { fsparam_flag("nsdelegate", Opt_nsdelegate), fsparam_flag("nonsdelegate", Opt_nonsdelegate), + fsparam_flag("favordynmods", Opt_favordynmods), + fsparam_flag("nofavordynmods", Opt_nofavordynmods), fsparam_flag("memory_localevents", Opt_memory_localevents), fsparam_flag("memory_nolocalevents", Opt_memory_nolocalevents), fsparam_flag("memory_recursiveprot", Opt_memory_recursiveprot), @@ -1890,6 +1908,12 @@ static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param case Opt_nonsdelegate: ctx->flags &= ~CGRP_ROOT_NS_DELEGATE; return 0; + case Opt_favordynmods: + ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS; + return 0; + case Opt_nofavordynmods: + ctx->flags &= ~CGRP_ROOT_FAVOR_DYNMODS; + return 0; case Opt_memory_localevents: ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS; return 0; @@ -1914,6 +1938,9 @@ static void apply_cgroup_root_flags(unsigned int root_flags) else cgrp_dfl_root.flags &= ~CGRP_ROOT_NS_DELEGATE; + cgroup_favor_dynmods(&cgrp_dfl_root, + root_flags & CGRP_ROOT_FAVOR_DYNMODS); + if (root_flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS) cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS; else @@ -1930,6 +1957,8 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root { if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) seq_puts(seq, ",nsdelegate"); + if (cgrp_dfl_root.flags & CGRP_ROOT_FAVOR_DYNMODS) + seq_puts(seq, ",favordynmods"); if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS) seq_puts(seq, ",memory_localevents"); if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT) @@ -1980,7 +2009,8 @@ void init_cgroup_root(struct cgroup_fs_context *ctx) cgrp->root = root; init_cgroup_housekeeping(cgrp); - root->flags = ctx->flags; + /* DYNMODS must be modified through cgroup_favor_dynmods() */ + root->flags = ctx->flags & ~CGRP_ROOT_FAVOR_DYNMODS; if (ctx->release_agent) strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX); if (ctx->name) @@ -2202,6 +2232,10 @@ static int cgroup_init_fs_context(struct fs_context *fc) put_user_ns(fc->user_ns); fc->user_ns = get_user_ns(ctx->ns->user_ns); fc->global = true; + +#ifdef CONFIG_CGROUP_FAVOR_DYNMODS + ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS; +#endif return 0; } @@ -5854,12 +5888,6 @@ int __init cgroup_init(void) cgroup_rstat_boot(); - /* - * The latency of the synchronize_rcu() is too high for cgroups, - * avoid it at the cost of forcing all readers into the slow path. - */ - rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss); - get_user_ns(init_cgroup_ns.user_ns); mutex_lock(&cgroup_mutex); @@ -6771,6 +6799,7 @@ static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr, { return snprintf(buf, PAGE_SIZE, "nsdelegate\n" + "favordynmods\n" "memory_localevents\n" "memory_recursiveprot\n"); } |