Signed-off-by: Jemmy Wong <jemmywong512@gmail.com>
---
kernel/cgroup/cgroup-internal.h | 8 ++--
kernel/cgroup/cgroup-v1.c | 11 +++--
kernel/cgroup/cgroup.c | 73 ++++++++++++---------------------
3 files changed, 35 insertions(+), 57 deletions(-)
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index b14e61c64a34..5430454d38ca 100644
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -198,8 +198,6 @@ void put_css_set_locked(struct css_set *cset);
static inline 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
@@ -208,9 +206,9 @@ static inline void put_css_set(struct css_set *cset)
if (refcount_dec_not_one(&cset->refcount))
return;
- spin_lock_irqsave(&css_set_lock, flags);
- put_css_set_locked(cset);
- spin_unlock_irqrestore(&css_set_lock, flags);
+ scoped_guard(spinlock_irqsave, &css_set_lock) {
+ put_css_set_locked(cset);
+ }
}
/*
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index fcc2d474b470..91c6ba4e441d 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -1291,7 +1291,6 @@ struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
{
struct cgroup *cgrp = ERR_PTR(-ENOENT);
struct cgroup_root *root;
- unsigned long flags;
guard(rcu)();
for_each_root(root) {
@@ -1300,11 +1299,11 @@ struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
continue;
if (root->hierarchy_id != hierarchy_id)
continue;
- spin_lock_irqsave(&css_set_lock, flags);
- cgrp = task_cgroup_from_root(tsk, root);
- if (!cgrp || !cgroup_tryget(cgrp))
- cgrp = ERR_PTR(-ENOENT);
- spin_unlock_irqrestore(&css_set_lock, flags);
+ scoped_guard(spinlock_irqsave, &css_set_lock) {
+ cgrp = task_cgroup_from_root(tsk, root);
+ if (!cgrp || !cgroup_tryget(cgrp))
+ cgrp = ERR_PTR(-ENOENT);
+ }
break;
}
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 46b677a066d1..ea98679b01e1 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -335,28 +335,23 @@ static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
int ret;
idr_preload(gfp_mask);
- spin_lock_bh(&cgroup_idr_lock);
- ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
- spin_unlock_bh(&cgroup_idr_lock);
+ scoped_guard(spinlock_bh, &cgroup_idr_lock) {
+ ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
+ }
idr_preload_end();
return ret;
}
static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
{
- void *ret;
-
- spin_lock_bh(&cgroup_idr_lock);
- ret = idr_replace(idr, ptr, id);
- spin_unlock_bh(&cgroup_idr_lock);
- return ret;
+ guard(spinlock_bh)(&cgroup_idr_lock);
+ return idr_replace(idr, ptr, id);
}
static void cgroup_idr_remove(struct idr *idr, int id)
{
- spin_lock_bh(&cgroup_idr_lock);
+ guard(spinlock_bh)(&cgroup_idr_lock);
idr_remove(idr, id);
- spin_unlock_bh(&cgroup_idr_lock);
}
static bool cgroup_has_tasks(struct cgroup *cgrp)
@@ -583,20 +578,19 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
if (!CGROUP_HAS_SUBSYS_CONFIG)
return NULL;
- rcu_read_lock();
+ guard(rcu)();
do {
css = cgroup_css(cgrp, ss);
if (css && css_tryget_online(css))
- goto out_unlock;
+ return css;
cgrp = cgroup_parent(cgrp);
} while (cgrp);
css = init_css_set.subsys[ss->id];
css_get(css);
-out_unlock:
- rcu_read_unlock();
+
return css;
}
EXPORT_SYMBOL_GPL(cgroup_get_e_css);
@@ -1691,9 +1685,9 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
struct cgroup_file *cfile = (void *)css + cft->file_offset;
- spin_lock_irq(&cgroup_file_kn_lock);
- cfile->kn = NULL;
- spin_unlock_irq(&cgroup_file_kn_lock);
+ scoped_guard(spinlock_irq, &cgroup_file_kn_lock) {
+ cfile->kn = NULL;
+ }
timer_delete_sync(&cfile->notify_timer);
}
@@ -4277,9 +4271,9 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0);
- spin_lock_irq(&cgroup_file_kn_lock);
- cfile->kn = kn;
- spin_unlock_irq(&cgroup_file_kn_lock);
+ scoped_guard(spinlock_irq, &cgroup_file_kn_lock) {
+ cfile->kn = kn;
+ }
}
return 0;
@@ -4534,9 +4528,7 @@ int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
*/
void cgroup_file_notify(struct cgroup_file *cfile)
{
- unsigned long flags;
-
- spin_lock_irqsave(&cgroup_file_kn_lock, flags);
+ guard(spinlock_irqsave)(&cgroup_file_kn_lock);
if (cfile->kn) {
unsigned long last = cfile->notified_at;
unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV;
@@ -4548,7 +4540,6 @@ void cgroup_file_notify(struct cgroup_file *cfile)
cfile->notified_at = jiffies;
}
}
- spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
}
/**
@@ -4560,10 +4551,10 @@ void cgroup_file_show(struct cgroup_file *cfile, bool show)
{
struct kernfs_node *kn;
- spin_lock_irq(&cgroup_file_kn_lock);
- kn = cfile->kn;
- kernfs_get(kn);
- spin_unlock_irq(&cgroup_file_kn_lock);
+ scoped_guard(spinlock_irq, &cgroup_file_kn_lock) {
+ kn = cfile->kn;
+ kernfs_get(kn);
+ }
if (kn)
kernfs_show(kn, show);
@@ -4987,11 +4978,10 @@ static void css_task_iter_advance(struct css_task_iter *it)
void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
struct css_task_iter *it)
{
- unsigned long irqflags;
memset(it, 0, sizeof(*it));
- spin_lock_irqsave(&css_set_lock, irqflags);
+ guard(spinlock_irqsave)(&css_set_lock);
it->ss = css->ss;
it->flags = flags;
@@ -5004,8 +4994,6 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
it->cset_head = it->cset_pos;
css_task_iter_advance(it);
-
- spin_unlock_irqrestore(&css_set_lock, irqflags);
}
/**
@@ -5018,14 +5006,12 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
*/
struct task_struct *css_task_iter_next(struct css_task_iter *it)
{
- unsigned long irqflags;
-
if (it->cur_task) {
put_task_struct(it->cur_task);
it->cur_task = NULL;
}
- spin_lock_irqsave(&css_set_lock, irqflags);
+ guard(spinlock_irqsave)(&css_set_lock);
/* @it may be half-advanced by skips, finish advancing */
if (it->flags & CSS_TASK_ITER_SKIPPED)
@@ -5038,8 +5024,6 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
css_task_iter_advance(it);
}
- spin_unlock_irqrestore(&css_set_lock, irqflags);
-
return it->cur_task;
}
@@ -5051,13 +5035,10 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
*/
void css_task_iter_end(struct css_task_iter *it)
{
- unsigned long irqflags;
-
if (it->cur_cset) {
- spin_lock_irqsave(&css_set_lock, irqflags);
+ guard(spinlock_irqsave)(&css_set_lock);
list_del(&it->iters_node);
put_css_set_locked(it->cur_cset);
- spin_unlock_irqrestore(&css_set_lock, irqflags);
}
if (it->cur_dcset)
@@ -6737,10 +6718,10 @@ void cgroup_post_fork(struct task_struct *child,
* too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to
* get the task into the frozen state.
*/
- spin_lock(&child->sighand->siglock);
- WARN_ON_ONCE(child->frozen);
- child->jobctl |= JOBCTL_TRAP_FREEZE;
- spin_unlock(&child->sighand->siglock);
+ scoped_guard(spinlock, &child->sighand->siglock) {
+ WARN_ON_ONCE(child->frozen);
+ child->jobctl |= JOBCTL_TRAP_FREEZE;
+ }
/*
* Calling cgroup_update_frozen() isn't required here,
--
2.43.0On Sat, Jun 07, 2025 at 12:18:41AM +0800, Jemmy Wong <jemmywong512@gmail.com> wrote:
> Signed-off-by: Jemmy Wong <jemmywong512@gmail.com>
>
> ---
> kernel/cgroup/cgroup-internal.h | 8 ++--
> kernel/cgroup/cgroup-v1.c | 11 +++--
> kernel/cgroup/cgroup.c | 73 ++++++++++++---------------------
> 3 files changed, 35 insertions(+), 57 deletions(-)
>
> diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
> index b14e61c64a34..5430454d38ca 100644
> --- a/kernel/cgroup/cgroup-internal.h
> +++ b/kernel/cgroup/cgroup-internal.h
> @@ -198,8 +198,6 @@ void put_css_set_locked(struct css_set *cset);
>
> static inline 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
> @@ -208,9 +206,9 @@ static inline void put_css_set(struct css_set *cset)
> if (refcount_dec_not_one(&cset->refcount))
> return;
>
> - spin_lock_irqsave(&css_set_lock, flags);
> - put_css_set_locked(cset);
> - spin_unlock_irqrestore(&css_set_lock, flags);
> + scoped_guard(spinlock_irqsave, &css_set_lock) {
> + put_css_set_locked(cset);
> + }
> }
This should go to the css_set_lock patch.
> /*
> diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
> index fcc2d474b470..91c6ba4e441d 100644
> --- a/kernel/cgroup/cgroup-v1.c
> +++ b/kernel/cgroup/cgroup-v1.c
> @@ -1291,7 +1291,6 @@ struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
> {
> struct cgroup *cgrp = ERR_PTR(-ENOENT);
> struct cgroup_root *root;
> - unsigned long flags;
>
> guard(rcu)();
> for_each_root(root) {
> @@ -1300,11 +1299,11 @@ struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
> continue;
> if (root->hierarchy_id != hierarchy_id)
> continue;
> - spin_lock_irqsave(&css_set_lock, flags);
> - cgrp = task_cgroup_from_root(tsk, root);
> - if (!cgrp || !cgroup_tryget(cgrp))
> - cgrp = ERR_PTR(-ENOENT);
> - spin_unlock_irqrestore(&css_set_lock, flags);
> + scoped_guard(spinlock_irqsave, &css_set_lock) {
> + cgrp = task_cgroup_from_root(tsk, root);
> + if (!cgrp || !cgroup_tryget(cgrp))
> + cgrp = ERR_PTR(-ENOENT);
> + }
Ditto.
> break;
> }
>
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index 46b677a066d1..ea98679b01e1 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -335,28 +335,23 @@ static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
> int ret;
>
> idr_preload(gfp_mask);
> - spin_lock_bh(&cgroup_idr_lock);
> - ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
> - spin_unlock_bh(&cgroup_idr_lock);
> + scoped_guard(spinlock_bh, &cgroup_idr_lock) {
> + ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
> + }
> idr_preload_end();
> return ret;
> }
>
> static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
> {
> - void *ret;
> -
> - spin_lock_bh(&cgroup_idr_lock);
> - ret = idr_replace(idr, ptr, id);
> - spin_unlock_bh(&cgroup_idr_lock);
> - return ret;
> + guard(spinlock_bh)(&cgroup_idr_lock);
> + return idr_replace(idr, ptr, id);
> }
>
> static void cgroup_idr_remove(struct idr *idr, int id)
> {
> - spin_lock_bh(&cgroup_idr_lock);
> + guard(spinlock_bh)(&cgroup_idr_lock);
> idr_remove(idr, id);
> - spin_unlock_bh(&cgroup_idr_lock);
> }
>
> static bool cgroup_has_tasks(struct cgroup *cgrp)
> @@ -583,20 +578,19 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
> if (!CGROUP_HAS_SUBSYS_CONFIG)
> return NULL;
>
> - rcu_read_lock();
> + guard(rcu)();
>
> do {
> css = cgroup_css(cgrp, ss);
>
> if (css && css_tryget_online(css))
> - goto out_unlock;
> + return css;
> cgrp = cgroup_parent(cgrp);
> } while (cgrp);
>
> css = init_css_set.subsys[ss->id];
> css_get(css);
> -out_unlock:
> - rcu_read_unlock();
> +
> return css;
> }
> EXPORT_SYMBOL_GPL(cgroup_get_e_css);
This should go to the RCU patch.
> @@ -1691,9 +1685,9 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
> struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
> struct cgroup_file *cfile = (void *)css + cft->file_offset;
>
> - spin_lock_irq(&cgroup_file_kn_lock);
> - cfile->kn = NULL;
> - spin_unlock_irq(&cgroup_file_kn_lock);
> + scoped_guard(spinlock_irq, &cgroup_file_kn_lock) {
> + cfile->kn = NULL;
> + }
>
> timer_delete_sync(&cfile->notify_timer);
> }
> @@ -4277,9 +4271,9 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
>
> timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0);
>
> - spin_lock_irq(&cgroup_file_kn_lock);
> - cfile->kn = kn;
> - spin_unlock_irq(&cgroup_file_kn_lock);
> + scoped_guard(spinlock_irq, &cgroup_file_kn_lock) {
> + cfile->kn = kn;
> + }
> }
>
> return 0;
> @@ -4534,9 +4528,7 @@ int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
> */
> void cgroup_file_notify(struct cgroup_file *cfile)
> {
> - unsigned long flags;
> -
> - spin_lock_irqsave(&cgroup_file_kn_lock, flags);
> + guard(spinlock_irqsave)(&cgroup_file_kn_lock);
> if (cfile->kn) {
> unsigned long last = cfile->notified_at;
> unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV;
> @@ -4548,7 +4540,6 @@ void cgroup_file_notify(struct cgroup_file *cfile)
> cfile->notified_at = jiffies;
> }
> }
> - spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
> }
>
> /**
> @@ -4560,10 +4551,10 @@ void cgroup_file_show(struct cgroup_file *cfile, bool show)
> {
> struct kernfs_node *kn;
>
> - spin_lock_irq(&cgroup_file_kn_lock);
> - kn = cfile->kn;
> - kernfs_get(kn);
> - spin_unlock_irq(&cgroup_file_kn_lock);
> + scoped_guard(spinlock_irq, &cgroup_file_kn_lock) {
> + kn = cfile->kn;
> + kernfs_get(kn);
> + }
>
> if (kn)
> kernfs_show(kn, show);
> @@ -4987,11 +4978,10 @@ static void css_task_iter_advance(struct css_task_iter *it)
> void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
> struct css_task_iter *it)
> {
> - unsigned long irqflags;
>
> memset(it, 0, sizeof(*it));
>
> - spin_lock_irqsave(&css_set_lock, irqflags);
> + guard(spinlock_irqsave)(&css_set_lock);
>
> it->ss = css->ss;
> it->flags = flags;
> @@ -5004,8 +4994,6 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
> it->cset_head = it->cset_pos;
>
> css_task_iter_advance(it);
> -
> - spin_unlock_irqrestore(&css_set_lock, irqflags);
> }
>
css_set_lock
> /**
> @@ -5018,14 +5006,12 @@ void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags,
> */
> struct task_struct *css_task_iter_next(struct css_task_iter *it)
> {
> - unsigned long irqflags;
> -
> if (it->cur_task) {
> put_task_struct(it->cur_task);
> it->cur_task = NULL;
> }
>
> - spin_lock_irqsave(&css_set_lock, irqflags);
> + guard(spinlock_irqsave)(&css_set_lock);
>
> /* @it may be half-advanced by skips, finish advancing */
> if (it->flags & CSS_TASK_ITER_SKIPPED)
> @@ -5038,8 +5024,6 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
> css_task_iter_advance(it);
> }
>
> - spin_unlock_irqrestore(&css_set_lock, irqflags);
> -
> return it->cur_task;
> }
>
css_set_lock
> @@ -5051,13 +5035,10 @@ struct task_struct *css_task_iter_next(struct css_task_iter *it)
> */
> void css_task_iter_end(struct css_task_iter *it)
> {
> - unsigned long irqflags;
> -
> if (it->cur_cset) {
> - spin_lock_irqsave(&css_set_lock, irqflags);
> + guard(spinlock_irqsave)(&css_set_lock);
> list_del(&it->iters_node);
> put_css_set_locked(it->cur_cset);
> - spin_unlock_irqrestore(&css_set_lock, irqflags);
> }
>
> if (it->cur_dcset)
css_set_lock
> @@ -6737,10 +6718,10 @@ void cgroup_post_fork(struct task_struct *child,
> * too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to
> * get the task into the frozen state.
> */
> - spin_lock(&child->sighand->siglock);
> - WARN_ON_ONCE(child->frozen);
> - child->jobctl |= JOBCTL_TRAP_FREEZE;
> - spin_unlock(&child->sighand->siglock);
> + scoped_guard(spinlock, &child->sighand->siglock) {
> + WARN_ON_ONCE(child->frozen);
> + child->jobctl |= JOBCTL_TRAP_FREEZE;
> + }
>
> /*
> * Calling cgroup_update_frozen() isn't required here,
> --
> 2.43.0
>
Hi Jemmy,
kernel test robot noticed the following build warnings:
[auto build test WARNING on tj-cgroup/for-next]
[also build test WARNING on linus/master next-20250606]
[cannot apply to v6.15]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Jemmy-Wong/cgroup-add-lock-guard-support-for-cgroup_muetx/20250607-002109
base: https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
patch link: https://lore.kernel.org/r/20250606161841.44354-4-jemmywong512%40gmail.com
patch subject: [PATCH v1 3/3] cgroup: add lock guard support for others
config: sparc-randconfig-r121-20250607 (https://download.01.org/0day-ci/archive/20250607/202506071822.ERv4i34r-lkp@intel.com/config)
compiler: sparc-linux-gcc (GCC) 8.5.0
reproduce: (https://download.01.org/0day-ci/archive/20250607/202506071822.ERv4i34r-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506071822.ERv4i34r-lkp@intel.com/
sparse warnings: (new ones prefixed by >>)
>> kernel/cgroup/cgroup.c:6721:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *l @@ got struct spinlock [noderef] __rcu * @@
kernel/cgroup/cgroup.c:6721:33: sparse: expected struct spinlock [usertype] *l
kernel/cgroup/cgroup.c:6721:33: sparse: got struct spinlock [noderef] __rcu *
kernel/cgroup/cgroup.c:345:13: sparse: sparse: context imbalance in 'cgroup_idr_replace' - wrong count at exit
kernel/cgroup/cgroup.c:351:13: sparse: sparse: context imbalance in 'cgroup_idr_remove' - wrong count at exit
kernel/cgroup/cgroup.c:626:5: sparse: sparse: context imbalance in 'cgroup_task_count' - wrong count at exit
kernel/cgroup/cgroup.c:2225:9: sparse: sparse: context imbalance in 'cgroup_do_get_tree' - different lock contexts for basic block
kernel/cgroup/cgroup.c:2418:5: sparse: sparse: context imbalance in 'cgroup_path_ns' - wrong count at exit
kernel/cgroup/cgroup.c:2734:9: sparse: sparse: context imbalance in 'cgroup_migrate_finish' - wrong count at exit
kernel/cgroup/cgroup.c:3131:9: sparse: sparse: context imbalance in 'cgroup_lock_and_drain_offline' - wrong count at exit
kernel/cgroup/cgroup.c:4532:9: sparse: sparse: context imbalance in 'cgroup_file_notify' - wrong count at exit
kernel/cgroup/cgroup.c:4994:9: sparse: sparse: context imbalance in 'css_task_iter_start' - wrong count at exit
kernel/cgroup/cgroup.c:5027:9: sparse: sparse: context imbalance in 'css_task_iter_next' - wrong count at exit
kernel/cgroup/cgroup.c:5047:9: sparse: sparse: context imbalance in 'css_task_iter_end' - wrong count at exit
kernel/cgroup/cgroup.c:6485:12: sparse: sparse: context imbalance in 'cgroup_css_set_fork' - wrong count at exit
kernel/cgroup/cgroup.c:6601:9: sparse: sparse: context imbalance in 'cgroup_css_set_put_fork' - wrong count at exit
kernel/cgroup/cgroup.c:6621:5: sparse: sparse: context imbalance in 'cgroup_can_fork' - wrong count at exit
kernel/cgroup/cgroup.c:6670:9: sparse: sparse: context imbalance in 'cgroup_cancel_fork' - unexpected unlock
kernel/cgroup/cgroup.c:6813:9: sparse: sparse: context imbalance in 'cgroup_release' - different lock contexts for basic block
vim +6721 kernel/cgroup/cgroup.c
6672
6673 /**
6674 * cgroup_post_fork - finalize cgroup setup for the child process
6675 * @child: the child process
6676 * @kargs: the arguments passed to create the child process
6677 *
6678 * Attach the child process to its css_set calling the subsystem fork()
6679 * callbacks.
6680 */
6681 void cgroup_post_fork(struct task_struct *child,
6682 struct kernel_clone_args *kargs)
6683 __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
6684 {
6685 unsigned int cgrp_kill_seq = 0;
6686 unsigned long cgrp_flags = 0;
6687 bool kill = false;
6688 struct cgroup_subsys *ss;
6689 struct css_set *cset;
6690 int i;
6691
6692 cset = kargs->cset;
6693 kargs->cset = NULL;
6694
6695 scoped_guard(spinlock_irq, &css_set_lock) {
6696 /* init tasks are special, only link regular threads */
6697 if (likely(child->pid)) {
6698 if (kargs->cgrp) {
6699 cgrp_flags = kargs->cgrp->flags;
6700 cgrp_kill_seq = kargs->cgrp->kill_seq;
6701 } else {
6702 cgrp_flags = cset->dfl_cgrp->flags;
6703 cgrp_kill_seq = cset->dfl_cgrp->kill_seq;
6704 }
6705
6706 WARN_ON_ONCE(!list_empty(&child->cg_list));
6707 cset->nr_tasks++;
6708 css_set_move_task(child, NULL, cset, false);
6709 } else {
6710 put_css_set(cset);
6711 cset = NULL;
6712 }
6713
6714 if (!(child->flags & PF_KTHREAD)) {
6715 if (unlikely(test_bit(CGRP_FREEZE, &cgrp_flags))) {
6716 /*
6717 * If the cgroup has to be frozen, the new task has
6718 * too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to
6719 * get the task into the frozen state.
6720 */
> 6721 scoped_guard(spinlock, &child->sighand->siglock) {
6722 WARN_ON_ONCE(child->frozen);
6723 child->jobctl |= JOBCTL_TRAP_FREEZE;
6724 }
6725
6726 /*
6727 * Calling cgroup_update_frozen() isn't required here,
6728 * because it will be called anyway a bit later from
6729 * do_freezer_trap(). So we avoid cgroup's transient
6730 * switch from the frozen state and back.
6731 */
6732 }
6733
6734 /*
6735 * If the cgroup is to be killed notice it now and take the
6736 * child down right after we finished preparing it for
6737 * userspace.
6738 */
6739 kill = kargs->kill_seq != cgrp_kill_seq;
6740 }
6741 }
6742 /*
6743 * Call ss->fork(). This must happen after @child is linked on
6744 * css_set; otherwise, @child might change state between ->fork()
6745 * and addition to css_set.
6746 */
6747 do_each_subsys_mask(ss, i, have_fork_callback) {
6748 ss->fork(child);
6749 } while_each_subsys_mask();
6750
6751 /* Make the new cset the root_cset of the new cgroup namespace. */
6752 if (kargs->flags & CLONE_NEWCGROUP) {
6753 struct css_set *rcset = child->nsproxy->cgroup_ns->root_cset;
6754
6755 get_css_set(cset);
6756 child->nsproxy->cgroup_ns->root_cset = cset;
6757 put_css_set(rcset);
6758 }
6759
6760 /* Cgroup has to be killed so take down child immediately. */
6761 if (unlikely(kill))
6762 do_send_sig_info(SIGKILL, SEND_SIG_NOINFO, child, PIDTYPE_TGID);
6763
6764 cgroup_css_set_put_fork(kargs);
6765 }
6766
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Hi Peter, Dam, Ingo,
Do you have any recommendations to eliminate this false positive, given that sparse recognizes scoped_guard but not guard?
Looks like false positives. Some of these warnings were already present
due to asymmetric lock/unlock behavior in a specific function,
while others were introduced by the use of guard,
which can be resolved by replacing it with scoped_guard,
but I don’t like this solution which could add additional indentation.
——
Previous warnings - caused by asymmetric lock/unlock:
kernel/cgroup/cgroup.c:3161:9: sparse: warning: context imbalance in 'cgroup_lock_and_drain_offline' - wrong count at exit
kernel/cgroup/cgroup.c:6530:12: sparse: warning: context imbalance in 'cgroup_css_set_fork' - wrong count at exit
kernel/cgroup/cgroup.c:6646:9: sparse: warning: context imbalance in 'cgroup_css_set_put_fork' - wrong count at exit
kernel/cgroup/cgroup.c:6666:5: sparse: warning: context imbalance in 'cgroup_can_fork' - wrong count at exit
kernel/cgroup/cgroup.c:6715:9: sparse: warning: context imbalance in 'cgroup_cancel_fork' - unexpected unlock
New warnings - caused by guard:
kernel/cgroup/cgroup.c:345:13: sparse: sparse: context imbalance in 'cgroup_idr_replace' - wrong count at exit
kernel/cgroup/cgroup.c:351:13: sparse: sparse: context imbalance in 'cgroup_idr_remove' - wrong count at exit
kernel/cgroup/cgroup.c:626:5: sparse: sparse: context imbalance in 'cgroup_task_count' - wrong count at exit
kernel/cgroup/cgroup.c:2225:9: sparse: sparse: context imbalance in 'cgroup_do_get_tree' - different lock contexts for basic block
kernel/cgroup/cgroup.c:2418:5: sparse: sparse: context imbalance in 'cgroup_path_ns' - wrong count at exit
kernel/cgroup/cgroup.c:2734:9: sparse: sparse: context imbalance in 'cgroup_migrate_finish' - wrong count at exit
kernel/cgroup/cgroup.c:4532:9: sparse: sparse: context imbalance in 'cgroup_file_notify' - wrong count at exit
kernel/cgroup/cgroup.c:4994:9: sparse: sparse: context imbalance in 'css_task_iter_start' - wrong count at exit
kernel/cgroup/cgroup.c:5027:9: sparse: sparse: context imbalance in 'css_task_iter_next' - wrong count at exit
kernel/cgroup/cgroup.c:5047:9: sparse: sparse: context imbalance in 'css_task_iter_end' - wrong count at exit
Best,
Jemmy
> On Jun 7, 2025, at 6:50 PM, kernel test robot <lkp@intel.com> wrote:
>
> Hi Jemmy,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on tj-cgroup/for-next]
> [also build test WARNING on linus/master next-20250606]
> [cannot apply to v6.15]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Jemmy-Wong/cgroup-add-lock-guard-support-for-cgroup_muetx/20250607-002109
> base: https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next
> patch link: https://lore.kernel.org/r/20250606161841.44354-4-jemmywong512%40gmail.com
> patch subject: [PATCH v1 3/3] cgroup: add lock guard support for others
> config: sparc-randconfig-r121-20250607 (https://download.01.org/0day-ci/archive/20250607/202506071822.ERv4i34r-lkp@intel.com/config)
> compiler: sparc-linux-gcc (GCC) 8.5.0
> reproduce: (https://download.01.org/0day-ci/archive/20250607/202506071822.ERv4i34r-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202506071822.ERv4i34r-lkp@intel.com/
>
> sparse warnings: (new ones prefixed by >>)
>>> kernel/cgroup/cgroup.c:6721:33: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct spinlock [usertype] *l @@ got struct spinlock [noderef] __rcu * @@
> kernel/cgroup/cgroup.c:6721:33: sparse: expected struct spinlock [usertype] *l
> kernel/cgroup/cgroup.c:6721:33: sparse: got struct spinlock [noderef] __rcu *
> kernel/cgroup/cgroup.c:345:13: sparse: sparse: context imbalance in 'cgroup_idr_replace' - wrong count at exit
> kernel/cgroup/cgroup.c:351:13: sparse: sparse: context imbalance in 'cgroup_idr_remove' - wrong count at exit
> kernel/cgroup/cgroup.c:626:5: sparse: sparse: context imbalance in 'cgroup_task_count' - wrong count at exit
> kernel/cgroup/cgroup.c:2225:9: sparse: sparse: context imbalance in 'cgroup_do_get_tree' - different lock contexts for basic block
> kernel/cgroup/cgroup.c:2418:5: sparse: sparse: context imbalance in 'cgroup_path_ns' - wrong count at exit
> kernel/cgroup/cgroup.c:2734:9: sparse: sparse: context imbalance in 'cgroup_migrate_finish' - wrong count at exit
> kernel/cgroup/cgroup.c:3131:9: sparse: sparse: context imbalance in 'cgroup_lock_and_drain_offline' - wrong count at exit
> kernel/cgroup/cgroup.c:4532:9: sparse: sparse: context imbalance in 'cgroup_file_notify' - wrong count at exit
> kernel/cgroup/cgroup.c:4994:9: sparse: sparse: context imbalance in 'css_task_iter_start' - wrong count at exit
> kernel/cgroup/cgroup.c:5027:9: sparse: sparse: context imbalance in 'css_task_iter_next' - wrong count at exit
> kernel/cgroup/cgroup.c:5047:9: sparse: sparse: context imbalance in 'css_task_iter_end' - wrong count at exit
> kernel/cgroup/cgroup.c:6485:12: sparse: sparse: context imbalance in 'cgroup_css_set_fork' - wrong count at exit
> kernel/cgroup/cgroup.c:6601:9: sparse: sparse: context imbalance in 'cgroup_css_set_put_fork' - wrong count at exit
> kernel/cgroup/cgroup.c:6621:5: sparse: sparse: context imbalance in 'cgroup_can_fork' - wrong count at exit
> kernel/cgroup/cgroup.c:6670:9: sparse: sparse: context imbalance in 'cgroup_cancel_fork' - unexpected unlock
> kernel/cgroup/cgroup.c:6813:9: sparse: sparse: context imbalance in 'cgroup_release' - different lock contexts for basic block
>
> vim +6721 kernel/cgroup/cgroup.c
>
> 6672
> 6673 /**
> 6674 * cgroup_post_fork - finalize cgroup setup for the child process
> 6675 * @child: the child process
> 6676 * @kargs: the arguments passed to create the child process
> 6677 *
> 6678 * Attach the child process to its css_set calling the subsystem fork()
> 6679 * callbacks.
> 6680 */
> 6681 void cgroup_post_fork(struct task_struct *child,
> 6682 struct kernel_clone_args *kargs)
> 6683 __releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
> 6684 {
> 6685 unsigned int cgrp_kill_seq = 0;
> 6686 unsigned long cgrp_flags = 0;
> 6687 bool kill = false;
> 6688 struct cgroup_subsys *ss;
> 6689 struct css_set *cset;
> 6690 int i;
> 6691
> 6692 cset = kargs->cset;
> 6693 kargs->cset = NULL;
> 6694
> 6695 scoped_guard(spinlock_irq, &css_set_lock) {
> 6696 /* init tasks are special, only link regular threads */
> 6697 if (likely(child->pid)) {
> 6698 if (kargs->cgrp) {
> 6699 cgrp_flags = kargs->cgrp->flags;
> 6700 cgrp_kill_seq = kargs->cgrp->kill_seq;
> 6701 } else {
> 6702 cgrp_flags = cset->dfl_cgrp->flags;
> 6703 cgrp_kill_seq = cset->dfl_cgrp->kill_seq;
> 6704 }
> 6705
> 6706 WARN_ON_ONCE(!list_empty(&child->cg_list));
> 6707 cset->nr_tasks++;
> 6708 css_set_move_task(child, NULL, cset, false);
> 6709 } else {
> 6710 put_css_set(cset);
> 6711 cset = NULL;
> 6712 }
> 6713
> 6714 if (!(child->flags & PF_KTHREAD)) {
> 6715 if (unlikely(test_bit(CGRP_FREEZE, &cgrp_flags))) {
> 6716 /*
> 6717 * If the cgroup has to be frozen, the new task has
> 6718 * too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to
> 6719 * get the task into the frozen state.
> 6720 */
>> 6721 scoped_guard(spinlock, &child->sighand->siglock) {
> 6722 WARN_ON_ONCE(child->frozen);
> 6723 child->jobctl |= JOBCTL_TRAP_FREEZE;
> 6724 }
> 6725
> 6726 /*
> 6727 * Calling cgroup_update_frozen() isn't required here,
> 6728 * because it will be called anyway a bit later from
> 6729 * do_freezer_trap(). So we avoid cgroup's transient
> 6730 * switch from the frozen state and back.
> 6731 */
> 6732 }
> 6733
> 6734 /*
> 6735 * If the cgroup is to be killed notice it now and take the
> 6736 * child down right after we finished preparing it for
> 6737 * userspace.
> 6738 */
> 6739 kill = kargs->kill_seq != cgrp_kill_seq;
> 6740 }
> 6741 }
> 6742 /*
> 6743 * Call ss->fork(). This must happen after @child is linked on
> 6744 * css_set; otherwise, @child might change state between ->fork()
> 6745 * and addition to css_set.
> 6746 */
> 6747 do_each_subsys_mask(ss, i, have_fork_callback) {
> 6748 ss->fork(child);
> 6749 } while_each_subsys_mask();
> 6750
> 6751 /* Make the new cset the root_cset of the new cgroup namespace. */
> 6752 if (kargs->flags & CLONE_NEWCGROUP) {
> 6753 struct css_set *rcset = child->nsproxy->cgroup_ns->root_cset;
> 6754
> 6755 get_css_set(cset);
> 6756 child->nsproxy->cgroup_ns->root_cset = cset;
> 6757 put_css_set(rcset);
> 6758 }
> 6759
> 6760 /* Cgroup has to be killed so take down child immediately. */
> 6761 if (unlikely(kill))
> 6762 do_send_sig_info(SIGKILL, SEND_SIG_NOINFO, child, PIDTYPE_TGID);
> 6763
> 6764 cgroup_css_set_put_fork(kargs);
> 6765 }
> 6766
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
© 2016 - 2025 Red Hat, Inc.