From 82d6489d0fed2ec8a8c48c19e8d8a04ac8e5bb26 Mon Sep 17 00:00:00 2001 From: Daniel Bristot de Oliveira Date: Wed, 22 Jun 2016 17:28:41 -0300 Subject: [PATCH] cgroup: Disable IRQs while holding css_set_lock While testing the deadline scheduler + cgroup setup I hit this warning. [ 132.612935] ------------[ cut here ]------------ [ 132.612951] WARNING: CPU: 5 PID: 0 at kernel/softirq.c:150 __local_bh_enable_ip+0x6b/0x80 [ 132.612952] Modules linked in: (a ton of modules...) [ 132.612981] CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.7.0-rc2 #2 [ 132.612981] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.2-20150714_191134- 04/01/2014 [ 132.612982] 0000000000000086 45c8bb5effdd088b ffff88013fd43da0 ffffffff813d229e [ 132.612984] 0000000000000000 0000000000000000 ffff88013fd43de0 ffffffff810a652b [ 132.612985] 00000096811387b5 0000000000000200 ffff8800bab29d80 ffff880034c54c00 [ 132.612986] Call Trace: [ 132.612987] [] dump_stack+0x63/0x85 [ 132.612994] [] __warn+0xcb/0xf0 [ 132.612997] [] ? push_dl_task.part.32+0x170/0x170 [ 132.612999] [] warn_slowpath_null+0x1d/0x20 [ 132.613000] [] __local_bh_enable_ip+0x6b/0x80 [ 132.613008] [] _raw_write_unlock_bh+0x1a/0x20 [ 132.613010] [] _raw_spin_unlock_bh+0xe/0x10 [ 132.613015] [] put_css_set+0x5c/0x60 [ 132.613016] [] cgroup_free+0x7f/0xa0 [ 132.613017] [] __put_task_struct+0x42/0x140 [ 132.613018] [] dl_task_timer+0xca/0x250 [ 132.613027] [] ? push_dl_task.part.32+0x170/0x170 [ 132.613030] [] __hrtimer_run_queues+0xee/0x270 [ 132.613031] [] hrtimer_interrupt+0xa8/0x190 [ 132.613034] [] local_apic_timer_interrupt+0x38/0x60 [ 132.613035] [] smp_apic_timer_interrupt+0x3d/0x50 [ 132.613037] [] apic_timer_interrupt+0x8c/0xa0 [ 132.613038] [] ? native_safe_halt+0x6/0x10 [ 132.613043] [] default_idle+0x1e/0xd0 [ 132.613044] [] arch_cpu_idle+0xf/0x20 [ 132.613046] [] default_idle_call+0x2a/0x40 [ 132.613047] [] cpu_startup_entry+0x2e7/0x340 [ 132.613048] [] start_secondary+0x155/0x190 [ 132.613049] ---[ end trace f91934d162ce9977 ]--- The warn is the spin_(lock|unlock)_bh(&css_set_lock) in the interrupt context. Converting the spin_lock_bh to spin_lock_irq(save) to avoid this problem - and other problems of sharing a spinlock with an interrupt. Cc: Tejun Heo Cc: Li Zefan Cc: Johannes Weiner Cc: Juri Lelli Cc: Steven Rostedt Cc: cgroups@vger.kernel.org Cc: stable@vger.kernel.org # 4.5+ Cc: linux-kernel@vger.kernel.org Reviewed-by: Rik van Riel Reviewed-by: "Luis Claudio R. Goncalves" Signed-off-by: Daniel Bristot de Oliveira Acked-by: Zefan Li Signed-off-by: Tejun Heo --- kernel/cgroup.c | 142 +++++++++++++++++++++++++----------------------- 1 file changed, 74 insertions(+), 68 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 688eb0cd1851..75c0ff00aca6 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -837,6 +837,8 @@ static void put_css_set_locked(struct css_set *cset) static void put_css_set(struct css_set *cset) { + unsigned long flags; + /* * Ensure that the refcount doesn't hit zero while any readers * can see it. Similar to atomic_dec_and_lock(), but for an @@ -845,9 +847,9 @@ static void put_css_set(struct css_set *cset) if (atomic_add_unless(&cset->refcount, -1, 1)) return; - spin_lock_bh(&css_set_lock); + spin_lock_irqsave(&css_set_lock, flags); put_css_set_locked(cset); - spin_unlock_bh(&css_set_lock); + spin_unlock_irqrestore(&css_set_lock, flags); } /* @@ -1070,11 +1072,11 @@ static struct css_set *find_css_set(struct css_set *old_cset, /* First see if we already have a cgroup group that matches * the desired set */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); cset = find_existing_css_set(old_cset, cgrp, template); if (cset) get_css_set(cset); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); if (cset) return cset; @@ -1102,7 +1104,7 @@ static struct css_set *find_css_set(struct css_set *old_cset, * find_existing_css_set() */ memcpy(cset->subsys, template, sizeof(cset->subsys)); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); /* Add reference counts and links from the new css_set. */ list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { struct cgroup *c = link->cgrp; @@ -1128,7 +1130,7 @@ static struct css_set *find_css_set(struct css_set *old_cset, css_get(css); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); return cset; } @@ -1192,7 +1194,7 @@ static void cgroup_destroy_root(struct cgroup_root *root) * Release all the links from cset_links to this hierarchy's * root cgroup */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { list_del(&link->cset_link); @@ -1200,7 +1202,7 @@ static void cgroup_destroy_root(struct cgroup_root *root) kfree(link); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); if (!list_empty(&root->root_list)) { list_del(&root->root_list); @@ -1600,11 +1602,11 @@ static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask) ss->root = dst_root; css->cgroup = dcgrp; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); hash_for_each(css_set_table, i, cset, hlist) list_move_tail(&cset->e_cset_node[ss->id], &dcgrp->e_csets[ss->id]); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); /* default hierarchy doesn't enable controllers by default */ dst_root->subsys_mask |= 1 << ssid; @@ -1640,10 +1642,10 @@ static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node, if (!buf) return -ENOMEM; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot); len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); if (len >= PATH_MAX) len = -ERANGE; @@ -1897,7 +1899,7 @@ static void cgroup_enable_task_cg_lists(void) { struct task_struct *p, *g; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); if (use_task_css_set_links) goto out_unlock; @@ -1922,8 +1924,12 @@ static void cgroup_enable_task_cg_lists(void) * entry won't be deleted though the process has exited. * Do it while holding siglock so that we don't end up * racing against cgroup_exit(). + * + * Interrupts were already disabled while acquiring + * the css_set_lock, so we do not need to disable it + * again when acquiring the sighand->siglock here. */ - spin_lock_irq(&p->sighand->siglock); + spin_lock(&p->sighand->siglock); if (!(p->flags & PF_EXITING)) { struct css_set *cset = task_css_set(p); @@ -1932,11 +1938,11 @@ static void cgroup_enable_task_cg_lists(void) list_add_tail(&p->cg_list, &cset->tasks); get_css_set(cset); } - spin_unlock_irq(&p->sighand->siglock); + spin_unlock(&p->sighand->siglock); } while_each_thread(g, p); read_unlock(&tasklist_lock); out_unlock: - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); } static void init_cgroup_housekeeping(struct cgroup *cgrp) @@ -2043,13 +2049,13 @@ static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) * Link the root cgroup in this hierarchy into all the css_set * objects. */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); hash_for_each(css_set_table, i, cset, hlist) { link_css_set(&tmp_links, cset, root_cgrp); if (css_set_populated(cset)) cgroup_update_populated(root_cgrp, true); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); BUG_ON(!list_empty(&root_cgrp->self.children)); BUG_ON(atomic_read(&root->nr_cgrps) != 1); @@ -2256,11 +2262,11 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, struct cgroup *cgrp; mutex_lock(&cgroup_mutex); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); cgrp = cset_cgroup_from_root(ns->root_cset, root); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb); @@ -2337,11 +2343,11 @@ char *cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen, char *ret; mutex_lock(&cgroup_mutex); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); return ret; @@ -2369,7 +2375,7 @@ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) char *path = NULL; mutex_lock(&cgroup_mutex); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); @@ -2382,7 +2388,7 @@ char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) path = buf; } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); return path; } @@ -2557,7 +2563,7 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset, * the new cgroup. There are no failure cases after here, so this * is the commit point. */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry(cset, &tset->src_csets, mg_node) { list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) { struct css_set *from_cset = task_css_set(task); @@ -2568,7 +2574,7 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset, put_css_set_locked(from_cset); } } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); /* * Migration is committed, all target tasks are now on dst_csets. @@ -2597,13 +2603,13 @@ static int cgroup_taskset_migrate(struct cgroup_taskset *tset, } } while_each_subsys_mask(); out_release_tset: - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_splice_init(&tset->dst_csets, &tset->src_csets); list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { list_splice_tail_init(&cset->mg_tasks, &cset->tasks); list_del_init(&cset->mg_node); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); return ret; } @@ -2634,7 +2640,7 @@ static void cgroup_migrate_finish(struct list_head *preloaded_csets) lockdep_assert_held(&cgroup_mutex); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) { cset->mg_src_cgrp = NULL; cset->mg_dst_cgrp = NULL; @@ -2642,7 +2648,7 @@ static void cgroup_migrate_finish(struct list_head *preloaded_csets) list_del_init(&cset->mg_preload_node); put_css_set_locked(cset); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); } /** @@ -2783,7 +2789,7 @@ static int cgroup_migrate(struct task_struct *leader, bool threadgroup, * already PF_EXITING could be freed from underneath us unless we * take an rcu_read_lock. */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); rcu_read_lock(); task = leader; do { @@ -2792,7 +2798,7 @@ static int cgroup_migrate(struct task_struct *leader, bool threadgroup, break; } while_each_thread(leader, task); rcu_read_unlock(); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); return cgroup_taskset_migrate(&tset, root); } @@ -2816,7 +2822,7 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp, return -EBUSY; /* look up all src csets */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); rcu_read_lock(); task = leader; do { @@ -2826,7 +2832,7 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp, break; } while_each_thread(leader, task); rcu_read_unlock(); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); /* prepare dst csets and commit */ ret = cgroup_migrate_prepare_dst(&preloaded_csets); @@ -2859,9 +2865,9 @@ static int cgroup_procs_write_permission(struct task_struct *task, struct cgroup *cgrp; struct inode *inode; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); while (!cgroup_is_descendant(dst_cgrp, cgrp)) cgrp = cgroup_parent(cgrp); @@ -2962,9 +2968,9 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) if (root == &cgrp_dfl_root) continue; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); from_cgrp = task_cgroup_from_root(from, root); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); retval = cgroup_attach_task(from_cgrp, tsk, false); if (retval) @@ -3080,7 +3086,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp) percpu_down_write(&cgroup_threadgroup_rwsem); /* look up all csses currently attached to @cgrp's subtree */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { struct cgrp_cset_link *link; @@ -3088,14 +3094,14 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp) cgroup_migrate_add_src(link->cset, dsct, &preloaded_csets); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); /* NULL dst indicates self on default hierarchy */ ret = cgroup_migrate_prepare_dst(&preloaded_csets); if (ret) goto out_finish; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { struct task_struct *task, *ntask; @@ -3107,7 +3113,7 @@ static int cgroup_update_dfl_csses(struct cgroup *cgrp) list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) cgroup_taskset_add(task, &tset); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); ret = cgroup_taskset_migrate(&tset, cgrp->root); out_finish: @@ -3908,10 +3914,10 @@ static int cgroup_task_count(const struct cgroup *cgrp) int count = 0; struct cgrp_cset_link *link; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry(link, &cgrp->cset_links, cset_link) count += atomic_read(&link->cset->refcount); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); return count; } @@ -4249,7 +4255,7 @@ void css_task_iter_start(struct cgroup_subsys_state *css, memset(it, 0, sizeof(*it)); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); it->ss = css->ss; @@ -4262,7 +4268,7 @@ void css_task_iter_start(struct cgroup_subsys_state *css, css_task_iter_advance_css_set(it); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); } /** @@ -4280,7 +4286,7 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it) it->cur_task = NULL; } - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); if (it->task_pos) { it->cur_task = list_entry(it->task_pos, struct task_struct, @@ -4289,7 +4295,7 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it) css_task_iter_advance(it); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); return it->cur_task; } @@ -4303,10 +4309,10 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it) void css_task_iter_end(struct css_task_iter *it) { if (it->cur_cset) { - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_del(&it->iters_node); put_css_set_locked(it->cur_cset); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); } if (it->cur_task) @@ -4338,10 +4344,10 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) mutex_lock(&cgroup_mutex); /* all tasks in @from are being moved, all csets are source */ - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry(link, &from->cset_links, cset_link) cgroup_migrate_add_src(link->cset, to, &preloaded_csets); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); ret = cgroup_migrate_prepare_dst(&preloaded_csets); if (ret) @@ -5449,10 +5455,10 @@ static int cgroup_destroy_locked(struct cgroup *cgrp) */ cgrp->self.flags &= ~CSS_ONLINE; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry(link, &cgrp->cset_links, cset_link) link->cset->dead = true; - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); /* initiate massacre of all css's */ for_each_css(css, ssid, cgrp) @@ -5723,7 +5729,7 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, goto out; mutex_lock(&cgroup_mutex); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); for_each_root(root) { struct cgroup_subsys *ss; @@ -5776,7 +5782,7 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, retval = 0; out_unlock: - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); kfree(buf); out: @@ -5921,13 +5927,13 @@ void cgroup_post_fork(struct task_struct *child) if (use_task_css_set_links) { struct css_set *cset; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); cset = task_css_set(current); if (list_empty(&child->cg_list)) { get_css_set(cset); css_set_move_task(child, NULL, cset, false); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); } /* @@ -5972,9 +5978,9 @@ void cgroup_exit(struct task_struct *tsk) cset = task_css_set(tsk); if (!list_empty(&tsk->cg_list)) { - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); css_set_move_task(tsk, cset, NULL, false); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); } else { get_css_set(cset); } @@ -6042,9 +6048,9 @@ static void cgroup_release_agent(struct work_struct *work) if (!pathbuf || !agentbuf) goto out; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); path = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); if (!path) goto out; @@ -6304,12 +6310,12 @@ struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, return ERR_PTR(-EPERM); mutex_lock(&cgroup_mutex); - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); cset = task_css_set(current); get_css_set(cset); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); new_ns = alloc_cgroup_ns(); @@ -6433,7 +6439,7 @@ static int current_css_set_cg_links_read(struct seq_file *seq, void *v) if (!name_buf) return -ENOMEM; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); rcu_read_lock(); cset = rcu_dereference(current->cgroups); list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { @@ -6444,7 +6450,7 @@ static int current_css_set_cg_links_read(struct seq_file *seq, void *v) c->root->hierarchy_id, name_buf); } rcu_read_unlock(); - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); kfree(name_buf); return 0; } @@ -6455,7 +6461,7 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) struct cgroup_subsys_state *css = seq_css(seq); struct cgrp_cset_link *link; - spin_lock_bh(&css_set_lock); + spin_lock_irq(&css_set_lock); list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { struct css_set *cset = link->cset; struct task_struct *task; @@ -6478,7 +6484,7 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) overflow: seq_puts(seq, " ...\n"); } - spin_unlock_bh(&css_set_lock); + spin_unlock_irq(&css_set_lock); return 0; } -- GitLab