From: Sasha Levin Date: Mon, 23 Sep 2024 08:47:40 +0000 (-0400) Subject: Fixes for 5.15 X-Git-Tag: v6.1.112~36 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4949d7faa2203a645eb3e9461ac91fa72a31c085;p=thirdparty%2Fkernel%2Fstable-queue.git Fixes for 5.15 Signed-off-by: Sasha Levin --- diff --git a/queue-5.15/cgroup-make-operations-on-the-cgroup-root_list-rcu-s.patch b/queue-5.15/cgroup-make-operations-on-the-cgroup-root_list-rcu-s.patch new file mode 100644 index 00000000000..96b185d16fe --- /dev/null +++ b/queue-5.15/cgroup-make-operations-on-the-cgroup-root_list-rcu-s.patch @@ -0,0 +1,122 @@ +From ab706590d83c4a3e1cfc39ea3609c3c153d078eb Mon Sep 17 00:00:00 2001 +From: Sasha Levin +Date: Sun, 29 Oct 2023 06:14:29 +0000 +Subject: cgroup: Make operations on the cgroup root_list RCU safe + +From: Yafang Shao + +[ Upstream commit d23b5c577715892c87533b13923306acc6243f93 ] + +At present, when we perform operations on the cgroup root_list, we must +hold the cgroup_mutex, which is a relatively heavyweight lock. In reality, +we can make operations on this list RCU-safe, eliminating the need to hold +the cgroup_mutex during traversal. Modifications to the list only occur in +the cgroup root setup and destroy paths, which should be infrequent in a +production environment. In contrast, traversal may occur frequently. +Therefore, making it RCU-safe would be beneficial. + +Signed-off-by: Yafang Shao +Signed-off-by: Tejun Heo +Signed-off-by: Sasha Levin +--- + include/linux/cgroup-defs.h | 1 + + kernel/cgroup/cgroup-internal.h | 3 ++- + kernel/cgroup/cgroup.c | 14 +++++++------- + 3 files changed, 10 insertions(+), 8 deletions(-) + +diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h +index cd8b8bd5ec4d5..61e92fd055d9c 100644 +--- a/include/linux/cgroup-defs.h ++++ b/include/linux/cgroup-defs.h +@@ -516,6 +516,7 @@ struct cgroup_root { + + /* A list running through the active hierarchies */ + struct list_head root_list; ++ struct rcu_head rcu; + + /* Hierarchy-specific flags */ + unsigned int flags; +diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h +index d8fcc139ac05d..f38f56b8cc416 100644 +--- a/kernel/cgroup/cgroup-internal.h ++++ b/kernel/cgroup/cgroup-internal.h +@@ -172,7 +172,8 @@ extern struct list_head cgroup_roots; + + /* iterate across the hierarchies */ + #define for_each_root(root) \ +- list_for_each_entry((root), &cgroup_roots, root_list) ++ list_for_each_entry_rcu((root), &cgroup_roots, root_list, \ ++ lockdep_is_held(&cgroup_mutex)) + + /** + * for_each_subsys - iterate all enabled cgroup subsystems +diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c +index 84e85561a87c0..999fef6d12282 100644 +--- a/kernel/cgroup/cgroup.c ++++ b/kernel/cgroup/cgroup.c +@@ -1332,7 +1332,7 @@ static void cgroup_exit_root_id(struct cgroup_root *root) + + void cgroup_free_root(struct cgroup_root *root) + { +- kfree(root); ++ kfree_rcu(root, rcu); + } + + static void cgroup_destroy_root(struct cgroup_root *root) +@@ -1365,7 +1365,7 @@ static void cgroup_destroy_root(struct cgroup_root *root) + spin_unlock_irq(&css_set_lock); + + if (!list_empty(&root->root_list)) { +- list_del(&root->root_list); ++ list_del_rcu(&root->root_list); + cgroup_root_count--; + } + +@@ -1411,7 +1411,6 @@ current_cgns_cgroup_from_root(struct cgroup_root *root) + } + rcu_read_unlock(); + +- BUG_ON(!res); + return res; + } + +@@ -1421,7 +1420,6 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset, + { + struct cgroup *res = NULL; + +- lockdep_assert_held(&cgroup_mutex); + lockdep_assert_held(&css_set_lock); + + if (cset == &init_css_set) { +@@ -1447,7 +1445,9 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset, + + /* + * Return the cgroup for "task" from the given hierarchy. Must be +- * called with cgroup_mutex and css_set_lock held. ++ * called with css_set_lock held to prevent task's groups from being modified. ++ * Must be called with either cgroup_mutex or rcu read lock to prevent the ++ * cgroup root from being destroyed. + */ + struct cgroup *task_cgroup_from_root(struct task_struct *task, + struct cgroup_root *root) +@@ -1986,7 +1986,7 @@ void init_cgroup_root(struct cgroup_fs_context *ctx) + struct cgroup_root *root = ctx->root; + struct cgroup *cgrp = &root->cgrp; + +- INIT_LIST_HEAD(&root->root_list); ++ INIT_LIST_HEAD_RCU(&root->root_list); + atomic_set(&root->nr_cgrps, 1); + cgrp->root = root; + init_cgroup_housekeeping(cgrp); +@@ -2068,7 +2068,7 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) + * care of subsystems' refcounts, which are explicitly dropped in + * the failure exit path. + */ +- list_add(&root->root_list, &cgroup_roots); ++ list_add_rcu(&root->root_list, &cgroup_roots); + cgroup_root_count++; + + /* +-- +2.43.0 + diff --git a/queue-5.15/series b/queue-5.15/series index 209bd01fbcd..372d069d0a5 100644 --- a/queue-5.15/series +++ b/queue-5.15/series @@ -84,3 +84,4 @@ x86-hyperv-set-x86_feature_tsc_known_freq-when-hyper.patch-27755 spi-spidev-add-missing-spi_device_id-for-jg10309-01.patch-32506 ocfs2-add-bounds-checking-to-ocfs2_xattr_find_entry.patch-32409 ocfs2-strict-bound-check-before-memcmp-in-ocfs2_xatt.patch-5953 +cgroup-make-operations-on-the-cgroup-root_list-rcu-s.patch