[PATCH v3 00/15] sched: introduce for_each_process_rculock and for_each_thread_rculock

From: Ye Liu <liuye@kylinos.cn>

Introduce for_each_process_rculock(), for_each_thread_rculock() and
for_each_process_thread_rculock() macros that combine the existing
iteration macros with scoped_guard(rcu), so that the RCU read lock
is automatically acquired before iteration and released when the
loop exits — including via break, goto, or return.

The rest of the series converts manual rcu_read_lock()/
rcu_read_unlock() and guard(rcu)() pairs across mm/, kernel/, fs/,
lib/ and security/ to use the new macros.

Suggested by Michal Hocko for the oom_kill path [2].

Signed-off-by: Ye Liu <liuye@kylinos.cn>

---
Changes since v2 [3]:
  - Split the kernel/ patch into per-subsystem patches, as the
    combined patch could not be applied (Peter Zijlstra, Steven
    Rostedt).
  - Move changelog below the --- separator so it is excluded from
    the commit message (Lorenzo Stoakes).
  - Indent loop body in macro definitions to show scoped_guard
    scope (Lorenzo Stoakes).

Changes since v1 [1]:
  - Rename macros from *_rcu to *_rculock, as suggested by Steven
    Rostedt and acked by Thomas Gleixner, to avoid confusion with
    existing *_rcu() list iterators that expect the caller to hold
    the RCU read lock.
  - Improve the comment on for_each_process_thread_rculock() to
    document that 'break' only exits the inner loop and 'goto' is
    needed to exit both loops (Thomas Gleixner).
  - Rename the stale 'unlock:' label to 'out:' in hung_task.c, as
    noted by Günther Noack.
  - Clarify in patch 4 that page_pgoff() is safe outside the RCU
    read-side critical section (SJ Park).
  - CC all relevant maintainers on every patch (Lorenzo Stoakes).
  - Drop the mm: prefix from patch 1, as the macros are in
    include/linux/sched/signal.h (Michal Hocko).

[1] https://lore.kernel.org/all/20260904083001.553587-1-ye.liu@linux.dev/
[2] https://lore.kernel.org/all/20260813092933.562028-1-ye.liu@linux.dev/
[3] https://lore.kernel.org/all/20260907081334.1152889-1-ye.liu@linux.dev/

Ye Liu (15):
  sched: introduce for_each_process_rculock and for_each_thread_rculock
  mm/oom_kill: convert process/thread iterators to for_each_*_rculock
  mm/ksm: convert process iterator to for_each_process_rculock
  mm/memory-failure: convert process iterator to for_each_process_rculock
  cpu/hotplug: convert thread iterator to for_each_thread_rculock
  freezer: convert thread iterator to for_each_thread_rculock
  hung_task: convert process/thread iterators to for_each_*_rculock
  locking/lockdep: convert process/thread iterators to for_each_*_rculock
  rcu: convert process/thread iterator to for_each_process_thread_rculock
  sched: convert process/thread iterators to for_each_*_rculock
  tracing/fgraph: convert process/thread iterator to for_each_process_thread_rculock
  unwind: convert process/thread iterator to for_each_process_thread_rculock
  fs: convert process/thread iterators to for_each_*_rculock
  lib: convert process iterator to for_each_process_rculock
  security/landlock: convert thread iterator to for_each_thread_rculock

 fs/proc/base.c               |  4 +---
 fs/resctrl/rdtgroup.c        |  8 ++------
 include/linux/sched/signal.h | 26 ++++++++++++++++++++++++++
 kernel/cpu.c                 |  4 +---
 kernel/freezer.c             |  4 +---
 kernel/hung_task.c           | 11 ++++-------
 kernel/locking/lockdep.c     |  4 +---
 kernel/rcu/update.c          |  4 +---
 kernel/sched/core.c          |  3 +--
 kernel/sched/debug.c         |  4 +---
 kernel/trace/fgraph.c        |  8 ++------
 kernel/unwind/deferred.c     |  3 +--
 lib/is_single_threaded.c     |  5 +----
 mm/ksm.c                     |  4 +---
 mm/memory-failure.c          | 16 ++++------------
 mm/oom_kill.c                | 20 +++++---------------
 security/landlock/tsync.c    |  8 ++------
 17 files changed, 55 insertions(+), 81 deletions(-)

--
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Introduce for_each_process_rculock(), for_each_thread_rculock() and
for_each_process_thread_rculock() macros that acquire the RCU read
lock before the iteration starts and release it when the loop is left,
so that the RCU read-side critical section is scoped to the loop body
instead of an externally managed rcu_read_lock()/rcu_read_unlock()
pair.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
---
Changes in v3:
  - Indent loop body to show scoped_guard scope (Lorenzo Stoakes)

Changes in v2:
  - Rename macros from *_rcu to *_rculock (Steven Rostedt, Thomas Gleixner)
  - Improve comment on for_each_process_thread_rculock() double loop
  - Change prefix from mm: to sched: (Michal Hocko)
 include/linux/sched/signal.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 584ae88b435e..ea23c7e9db33 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h

@@ -2,6 +2,7 @@
 #ifndef _LINUX_SCHED_SIGNAL_H
 #define _LINUX_SCHED_SIGNAL_H
 
+#include <linux/cleanup.h>
 #include <linux/rculist.h>
 #include <linux/signal.h>
 #include <linux/sched.h>

@@ -663,6 +664,31 @@ extern bool current_is_single_threaded(void);
 #define for_each_process_thread(p, t)	\
 	for_each_process(p) for_each_thread(p, t)
 
+/*
+ * Variants of for_each_process(), for_each_thread() and
+ * for_each_process_thread() that automatically acquire and release the
+ * RCU read lock via scoped_guard(rcu).  The lock is held for the
+ * duration of the loop and released on exit, including via break,
+ * goto, or return.
+ */
+#define for_each_process_rculock(p) \
+	scoped_guard(rcu) \
+		for (p = &init_task ; (p = next_task(p)) != &init_task ; )
+
+#define for_each_thread_rculock(p, t) \
+	scoped_guard(rcu) \
+		__for_each_thread((p)->signal, t)
+
+/*
+ * Double loop: 'break' only exits the inner for_each_thread() loop.
+ * Use 'goto' to exit both loops; the RCU read lock is released
+ * automatically when the scoped_guard scope is left.
+ */
+#define for_each_process_thread_rculock(p, t) \
+	scoped_guard(rcu) \
+		for_each_process(p) \
+			for_each_thread(p, t)
+
 typedef int (*proc_visitor)(struct task_struct *p, void *data);
 void walk_process_tree(struct task_struct *top, proc_visitor, void *);
 

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pairs wrapping
for_each_process()/for_each_thread() loops with for_each_process_rculock()
and for_each_thread_rculock(), which scope the RCU read lock to the
loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
---
Changes in v2:
  - Rename *_rcu to *_rculock
 mm/oom_kill.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 5f372f6e26fa..ef2e1c423c1d 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c

@@ -94,8 +94,7 @@ static bool oom_cpuset_eligible(struct task_struct *start,
 	bool ret = false;
 	const nodemask_t *mask = oc->nodemask;
 
-	rcu_read_lock();
-	for_each_thread(start, tsk) {
+	for_each_thread_rculock(start, tsk) {
 		if (mask) {
 			/*
 			 * If this is a mempolicy constrained oom, tsk's

@@ -114,7 +113,6 @@ static bool oom_cpuset_eligible(struct task_struct *start,
 		if (ret)
 			break;
 	}
-	rcu_read_unlock();
 
 	return ret;
 }

@@ -368,11 +366,9 @@ static void select_bad_process(struct oom_control *oc)
 	else {
 		struct task_struct *p;
 
-		rcu_read_lock();
-		for_each_process(p)
+		for_each_process_rculock(p)
 			if (oom_evaluate_task(p, oc))
 				break;
-		rcu_read_unlock();
 	}
 }
 

@@ -430,14 +426,12 @@ static void dump_tasks(struct oom_control *oc)
 		struct task_struct *p;
 		int i = 0;
 
-		rcu_read_lock();
-		for_each_process(p) {
+		for_each_process_rculock(p) {
 			/* Avoid potential softlockup warning */
 			if ((++i & 1023) == 0)
 				touch_softlockup_watchdog();
 			dump_task(p, oc);
 		}
-		rcu_read_unlock();
 	}
 }
 

@@ -894,8 +888,7 @@ static bool task_will_free_mem(struct task_struct *task)
 	 * are dying as well to make sure that a) nobody pins its mm and
 	 * b) the task is also reapable by the oom reaper.
 	 */
-	rcu_read_lock();
-	for_each_process(p) {
+	for_each_process_rculock(p) {
 		if (!process_shares_mm(p, mm))
 			continue;
 		if (same_thread_group(task, p))

@@ -904,7 +897,6 @@ static bool task_will_free_mem(struct task_struct *task)
 		if (!ret)
 			break;
 	}
-	rcu_read_unlock();
 
 	return ret;
 }

@@ -960,8 +952,7 @@ static void __oom_kill_process(struct task_struct *victim, const char *message)
 	 * That thread will now get access to memory reserves since it has a
 	 * pending fatal signal.
 	 */
-	rcu_read_lock();
-	for_each_process(p) {
+	for_each_process_rculock(p) {
 		if (!process_shares_mm(p, mm))
 			continue;
 		if (same_thread_group(p, victim))

@@ -982,7 +973,6 @@ static void __oom_kill_process(struct task_struct *victim, const char *message)
 			continue;
 		do_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_TGID);
 	}
-	rcu_read_unlock();
 
 	if (can_oom_reap)
 		queue_oom_reaper(victim);

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process() loop in mm/ksm.c with for_each_process_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
---
Changes in v2:
  - Rename *_rcu to *_rculock
 mm/ksm.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 49d48d1e0998..69d30e80a090 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c

@@ -3280,8 +3280,7 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page,
 		struct anon_vma *av = rmap_item->anon_vma;
 
 		anon_vma_lock_read(av);
-		rcu_read_lock();
-		for_each_process(tsk) {
+		for_each_process_rculock(tsk) {
 			struct anon_vma_chain *vmac;
 			const unsigned long addr = rmap_item->address & PAGE_MASK;
 			const unsigned long index = rmap_item->linear_page_index;

@@ -3298,7 +3297,6 @@ void collect_procs_ksm(const struct folio *folio, const struct page *page,
 				}
 			}
 		}
-		rcu_read_unlock();
 		anon_vma_unlock_read(av);
 	}
 }

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pairs combined
with for_each_process() loop in mm/memory-failure.c with
for_each_process_rculock(), which scopes the RCU read lock to the
loop body via scoped_guard(rcu).

In collect_procs_file(), the page_pgoff() call now falls outside the
RCU read-side critical section.  This is safe because page_pgoff()
only reads folio->index and does not traverse any RCU-protected
structures.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
---
Changes in v2:
  - Rename *_rcu to *_rculock
  - Clarify page_pgoff() safety outside RCU lock (SJ Park)
 mm/memory-failure.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index a8b03e2920ba..7d93deb1f7b3 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c

@@ -555,8 +555,7 @@ static void collect_procs_anon(const struct folio *folio,
 		return;
 
 	pgoff = page_pgoff(folio, page);
-	rcu_read_lock();
-	for_each_process(tsk) {
+	for_each_process_rculock(tsk) {
 		struct vm_area_struct *vma;
 		struct anon_vma_chain *vmac;
 		struct task_struct *t = task_early_kill(tsk, force_early);

@@ -572,7 +571,6 @@ static void collect_procs_anon(const struct folio *folio,
 			add_to_kill_anon_file(t, page, vma, to_kill, addr);
 		}
 	}
-	rcu_read_unlock();
 	anon_vma_unlock_read(av);
 }
 

@@ -589,9 +587,8 @@ static void collect_procs_file(const struct folio *folio,
 	pgoff_t pgoff;
 
 	i_mmap_lock_read(mapping);
-	rcu_read_lock();
 	pgoff = page_pgoff(folio, page);
-	for_each_process(tsk) {
+	for_each_process_rculock(tsk) {
 		struct task_struct *t = task_early_kill(tsk, force_early);
 		unsigned long addr;
 

@@ -611,7 +608,6 @@ static void collect_procs_file(const struct folio *folio,
 			add_to_kill_anon_file(t, page, vma, to_kill, addr);
 		}
 	}
-	rcu_read_unlock();
 	i_mmap_unlock_read(mapping);
 }
 

@@ -635,8 +631,7 @@ static void collect_procs_fsdax(const struct page *page,
 	struct task_struct *tsk;
 
 	i_mmap_lock_read(mapping);
-	rcu_read_lock();
-	for_each_process(tsk) {
+	for_each_process_rculock(tsk) {
 		struct task_struct *t = tsk;
 
 		/*

@@ -653,7 +648,6 @@ static void collect_procs_fsdax(const struct page *page,
 				add_to_kill_fsdax(t, page, vma, to_kill, pgoff);
 		}
 	}
-	rcu_read_unlock();
 	i_mmap_unlock_read(mapping);
 }
 #endif /* CONFIG_FS_DAX */

@@ -2288,8 +2282,7 @@ static void collect_procs_pfn(struct pfn_address_space *pfn_space,
 	struct address_space *mapping = pfn_space->mapping;
 
 	i_mmap_lock_read(mapping);
-	rcu_read_lock();
-	for_each_process(tsk) {
+	for_each_process_rculock(tsk) {
 		struct task_struct *t = tsk;
 
 		t = task_early_kill(tsk, true);

@@ -2303,7 +2296,6 @@ static void collect_procs_pfn(struct pfn_address_space *pfn_space,
 				add_to_kill_pgoff(t, vma, to_kill, pgoff);
 		}
 	}
-	rcu_read_unlock();
 	i_mmap_unlock_read(mapping);
 }
 

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_thread() loop in kernel/cpu.c with for_each_thread_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/cpu.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b3c8553d7bd6..00638d2abc0f 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c

@@ -1254,8 +1254,7 @@ void clear_tasks_mm_cpumask(int cpu)
 	 * full-fledged tasklist_lock.
 	 */
 	WARN_ON(cpu_online(cpu));
-	rcu_read_lock();
-	for_each_process(p) {
+	for_each_process_rculock(p) {
 		struct task_struct *t;
 
 		/*

@@ -1268,7 +1267,6 @@ void clear_tasks_mm_cpumask(int cpu)
 		arch_clear_mm_cpumask_cpu(cpu, t->mm);
 		task_unlock(t);
 	}
-	rcu_read_unlock();
 }
 
 /* Take this CPU down. */

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_thread() loop in kernel/freezer.c with
for_each_thread_rculock(), which scopes the RCU read lock to the
loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/freezer.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/freezer.c b/kernel/freezer.c
index a76bf957fb32..7a870f71dcf6 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c

@@ -217,11 +217,9 @@ void thaw_process(struct task_struct *p)
 {
 	struct task_struct *t;
 
-	rcu_read_lock();
-	for_each_thread(p, t) {
+	for_each_thread_rculock(p, t) {
 		__thaw_task(t);
 	}
-	rcu_read_unlock();
 }
 
 /**

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process_thread() loop in kernel/hung_task.c with
for_each_process_thread_rculock(), which scopes the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
  - Rename stale 'unlock:' label to 'out:' in hung_task.c (Günther Noack)
 kernel/hung_task.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 6fcc94ce4ca9..73a5ad3be9a8 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c

@@ -315,13 +315,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 		return;
 
 	this_round_count = 0;
-	rcu_read_lock();
-	for_each_process_thread(g, t) {
+	for_each_process_thread_rculock(g, t) {
 		if (!max_count--)
-			goto unlock;
+			goto out;
 		if (time_after(jiffies, last_break + HUNG_TASK_LOCK_BREAK)) {
 			if (!rcu_lock_break(g, t))
-				goto unlock;
+				goto out;
 			last_break = jiffies;
 		}
 

@@ -337,9 +336,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 			hung_task_info(t, timeout, this_round_count);
 		}
 	}
- unlock:
-	rcu_read_unlock();
-
+out:
 	if (!this_round_count)
 		return;
 

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process_thread() loop in kernel/locking/lockdep.c with
for_each_process_thread_rculock(), which scopes the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/locking/lockdep.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c56a7f91d72e..ea218dc75ad5 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c

@@ -6834,15 +6834,13 @@ void debug_show_all_locks(void)
 	}
 	pr_warn("\nShowing all locks held in the system:\n");
 
-	rcu_read_lock();
-	for_each_process_thread(g, p) {
+	for_each_process_thread_rculock(g, p) {
 		if (!p->lockdep_depth)
 			continue;
 		lockdep_print_held_locks(p);
 		touch_nmi_watchdog();
 		touch_all_softlockup_watchdogs();
 	}
-	rcu_read_unlock();
 
 	pr_warn("\n");
 	pr_warn("=============================================\n\n");

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process_thread() loop in kernel/rcu/update.c with
for_each_process_thread_rculock(), which scopes the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/rcu/update.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 2a778b8ab4ad..d8e0b5896db9 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c

@@ -548,15 +548,13 @@ void synchronize_rcu_trivial_preempt(void)
 	struct task_struct *t;
 
 	smp_mb(); // Order prior accesses before grace-period start.
-	rcu_read_lock(); // Protect task list.
-	for_each_process_thread(g, t) {
+	for_each_process_thread_rculock(g, t) {
 		if (t == current)
 			continue;  // Don't deadlock on ourselves!
 		// Order later rcu_read_lock() on other tasks after QS.
 		while (smp_load_acquire(&t->rcu_trivial_preempt_nesting))
 			continue;
 	}
-	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(synchronize_rcu_trivial_preempt);
 #endif // #if IS_ENABLED(CONFIG_TRIVIAL_PREEMPT_RCU)

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() and guard(rcu)
pairs combined with for_each_process_thread() loops in kernel/sched/
with for_each_process_thread_rculock(), which scopes the RCU read
lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/sched/core.c  | 3 +--
 kernel/sched/debug.c | 4 +---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0697ed0f1c3d..fd5bdd2cb798 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c

@@ -2005,8 +2005,7 @@ static void uclamp_sync_util_min_rt_default(void)
 	smp_mb__after_spinlock();
 	read_unlock(&tasklist_lock);
 
-	guard(rcu)();
-	for_each_process_thread(g, p)
+	for_each_process_thread_rculock(g, p)
 		uclamp_update_util_min_rt_default(p);
 }
 

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 72236db67983..cdae165b98f7 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c

@@ -1029,14 +1029,12 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
 #endif
 		   "\n");
 
-	rcu_read_lock();
-	for_each_process_thread(g, p) {
+	for_each_process_thread_rculock(g, p) {
 		if (task_cpu(p) != rq_cpu)
 			continue;
 
 		print_task(m, rq, p);
 	}
-	rcu_read_unlock();
 }
 
 void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process_thread() loop in kernel/trace/fgraph.c with
for_each_process_thread_rculock(), which scopes the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/trace/fgraph.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 40d373d65f9b..f797ce119223 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c

@@ -1057,11 +1057,10 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list)
 		}
 	}
 
-	rcu_read_lock();
-	for_each_process_thread(g, t) {
+	for_each_process_thread_rculock(g, t) {
 		if (start == end) {
 			ret = -EAGAIN;
-			goto unlock;
+			goto free;
 		}
 
 		if (t->ret_stack == NULL) {

@@ -1074,9 +1073,6 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list)
 			t->ret_stack = ret_stack_list[start++];
 		}
 	}
-
-unlock:
-	rcu_read_unlock();
 free:
 	for (i = start; i < end; i++)
 		kmem_cache_free(fgraph_stack_cachep, ret_stack_list[i]);

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace guard(rcu)() combined with for_each_process_thread() loop in
kernel/unwind/deferred.c with for_each_process_thread_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
---
Changes in v3:
  - Split from kernel/ patch in v2 (Peter Zijlstra, Steven Rostedt)

Changes in v2:
  - Rename *_rcu to *_rculock
 kernel/unwind/deferred.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/unwind/deferred.c b/kernel/unwind/deferred.c
index 5bea47314254..ecfe1336095e 100644
--- a/kernel/unwind/deferred.c
+++ b/kernel/unwind/deferred.c

@@ -319,9 +319,8 @@ void unwind_deferred_cancel(struct unwind_work *work)
 
 	synchronize_srcu(&unwind_srcu);
 
-	guard(rcu)();
 	/* Clear this bit from all threads */
-	for_each_process_thread(g, t) {
+	for_each_process_thread_rculock(g, t) {
 		atomic_long_andnot(BIT(bit),
 				   &t->unwind_info.unwind_mask);
 		if (t->unwind_info.cache)

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pairs combined
with for_each_process() and for_each_process_thread() loops in fs/
with the for_each_*_rculock() macros, which scope the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
---
Changes in v2:
  - Rename *_rcu to *_rculock
 fs/proc/base.c        | 4 +---
 fs/resctrl/rdtgroup.c | 8 ++------
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6a39de424f62..3de4f4557e4c 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c

@@ -1160,8 +1160,7 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
 	if (mm) {
 		struct task_struct *p;
 
-		rcu_read_lock();
-		for_each_process(p) {
+		for_each_process_rculock(p) {
 			if (same_thread_group(task, p))
 				continue;
 

@@ -1177,7 +1176,6 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
 			}
 			task_unlock(p);
 		}
-		rcu_read_unlock();
 		mmdrop(mm);
 	}
 err_unlock:

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5dcbb0a964e8..b14df8b23f1a 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c

@@ -709,14 +709,12 @@ int rdtgroup_tasks_assigned(struct rdtgroup *r)
 
 	lockdep_assert_held(&rdtgroup_mutex);
 
-	rcu_read_lock();
-	for_each_process_thread(p, t) {
+	for_each_process_thread_rculock(p, t) {
 		if (is_closid_match(t, r) || is_rmid_match(t, r)) {
 			ret = 1;
 			break;
 		}
 	}
-	rcu_read_unlock();
 
 	return ret;
 }

@@ -826,15 +824,13 @@ static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s)
 	struct task_struct *p, *t;
 	pid_t pid;
 
-	rcu_read_lock();
-	for_each_process_thread(p, t) {
+	for_each_process_thread_rculock(p, t) {
 		if (is_closid_match(t, r) || is_rmid_match(t, r)) {
 			pid = task_pid_vnr(t);
 			if (pid)
 				seq_printf(s, "%d\n", pid);
 		}
 	}
-	rcu_read_unlock();
 }
 
 static int rdtgroup_tasks_show(struct kernfs_open_file *of,

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process() loop in lib/ with for_each_process_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: SJ Park <sj@kernel.org>
---
Changes in v2:
  - Rename *_rcu to *_rculock
 lib/is_single_threaded.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/lib/is_single_threaded.c b/lib/is_single_threaded.c
index 8c98b20bfc41..4e7fe85454ab 100644
--- a/lib/is_single_threaded.c
+++ b/lib/is_single_threaded.c

@@ -26,8 +26,7 @@ bool current_is_single_threaded(void)
 		return true;
 
 	ret = false;
-	rcu_read_lock();
-	for_each_process(p) {
+	for_each_process_rculock(p) {
 		if (unlikely(p->flags & PF_KTHREAD))
 			continue;
 		if (unlikely(p == task->group_leader))

@@ -48,7 +47,5 @@ bool current_is_single_threaded(void)
 	}
 	ret = true;
 found:
-	rcu_read_unlock();
-
 	return ret;
 }

-- 
2.25.1

From: Ye Liu <liuye@kylinos.cn>

Replace guard(rcu)() + for_each_thread() with for_each_thread_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Reviewed-by: Justin Suess <redacted>
Reviewed-by: Günther Noack <redacted>
Reviewed-by: Gregory Price (Meta) <gourry@gourry.net>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
---
Changes in v2:
  - Rename *_rcu to *_rculock
 security/landlock/tsync.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/security/landlock/tsync.c b/security/landlock/tsync.c
index 0b71e158c3f5..a578af640aad 100644
--- a/security/landlock/tsync.c
+++ b/security/landlock/tsync.c

@@ -335,9 +335,7 @@ static size_t count_additional_threads(const struct tsync_works *works)
 
 	caller = current;
 
-	guard(rcu)();
-
-	for_each_thread(caller, thread) {
+	for_each_thread_rculock(caller, thread) {
 		/* Skip current, since it is initiating the sync. */
 		if (thread == caller)
 			continue;

@@ -376,9 +374,7 @@ static bool schedule_task_work(struct tsync_works *works,
 
 	caller = current;
 
-	guard(rcu)();
-
-	for_each_thread(caller, thread) {
+	for_each_thread_rculock(caller, thread) {
 		/* Skip current, since it is initiating the sync. */
 		if (thread == caller)
 			continue;

-- 
2.25.1

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Mixing goto-based error handling and scope-based guard() cleanup in the same function.
--

commit 70fc208f5f44114137a3c935785ed1ab665ae0e0
Author: Ye Liu [off-list ref]

tracing/fgraph: convert process/thread iterator to for_each_process_thread_rculock

This commit replaces the manual rcu_read_lock() and rcu_read_unlock() pair
combined with the for_each_process_thread() loop in fgraph.c with the
for_each_process_thread_rculock() macro, which scopes the RCU read lock to
the loop body via scoped_guard(rcu).

[ ... ]

[Severity: Low]
Does this mix scope-based cleanup with manual goto-based error handling?

By replacing the manual RCU lock with for_each_process_thread_rculock()
(which uses scoped_guard(rcu)), the function now relies on scope-based
cleanup for the RCU lock, but still jumps to a manual "goto free" label
for the memory cleanup below.

The cleanup guidelines state that for a given routine, we should convert all
resources that need a "goto" cleanup to scope-based cleanup, or convert none
of them, avoiding mixed usage in the same function.

 		}
 
 		if (t->ret_stack == NULL) {

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911075800.491472-1-ye.liu@linux.dev?part=11

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The commit message incorrectly claims to replace `for_each_thread()` with `for_each_thread_rculock()`, but the code actually replaces `for_each_process()` with `for_each_process_rculock()`.
--

commit 3ac98de6fbc4e97ba4981ef0c4941692c15a9309
Author: Ye Liu [off-list ref]

cpu/hotplug: convert thread iterator to for_each_thread_rculock

This commit replaces a manual rcu_read_lock() and rcu_read_unlock() pair
in clear_tasks_mm_cpumask() with a scoped RCU lock iterator macro.

cpu/hotplug: convert thread iterator to for_each_thread_rculock
    
Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_thread() loop in kernel/cpu.c with for_each_thread_rculock(),

[Severity: Medium]
Is the commit message accurate regarding the iterator being replaced?

The commit message subject and body describe converting a thread iterator
using for_each_thread() to for_each_thread_rculock(). However, looking at
clear_tasks_mm_cpumask() in the diff:

The code actually replaces for_each_process() with for_each_process_rculock().

Could the commit message be updated to match the process iterator actually
used in the patch to avoid confusion during review or bisection?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911075800.491472-1-ye.liu@linux.dev?part=5

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Potential NULL pointer dereference or Use-After-Free of `folio->mapping` in `collect_procs_file()` due to concurrent truncation.
--

commit 788d1f422c3f19026d9e0d86b550c238607720ed
Author: Ye Liu [off-list ref]

mm/memory-failure: convert process iterator to for_each_process_rculock

This commit replaces the manual rcu_read_lock()/rcu_read_unlock() pairs
combined with for_each_process() loop in mm/memory-failure.c with
for_each_process_rculock(), which scopes the RCU read lock to the loop body
via scoped_guard(rcu).

[ ... ]

[Severity: High]
This is a pre-existing issue, but could this lead to a NULL pointer
dereference or a use-after-free of mapping due to a race with truncation?

In memory_failure(), the folio lock is dropped in hwpoison_user_mappings()
before calling collect_procs(). collect_procs() performs an unlocked check of
!folio->mapping:

static void collect_procs(...)
{
	if (!folio->mapping)
		return;
	...
	else
		collect_procs_file(folio, page, tokill, force_early);
}

If a concurrent truncation removes the folio from the page cache immediately
after this check, folio->mapping becomes NULL. collect_procs_file() then
initializes mapping = folio->mapping and calls i_mmap_lock_read(mapping).

If the compiler performs a second read of folio->mapping, mapping will be
NULL, crashing the kernel on the semaphore acquisition. If the compiler
caches the first read, mapping will point to an address_space whose host
inode may have been concurrently freed, leading to a use-after-free since
the elevated page refcount does not pin the inode and no RCU read lock is
held during the blocking i_mmap_lock_read() call.

-	rcu_read_lock();
 	pgoff = page_pgoff(folio, page);
-	for_each_process(tsk) {
+	for_each_process_rculock(tsk) {
 		struct task_struct *t = task_early_kill(tsk, force_early);
 		unsigned long addr;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911075800.491472-1-ye.liu@linux.dev?part=4

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Mixing `goto`-based error handling with scope-based cleanup helpers in `__set_oom_adj()`.
--

commit dca26f99f6fe0ae1bf52a29a296c82180cb53c70
Author: Ye Liu [off-list ref]
Subject: fs: convert process/thread iterators to for_each_*_rculock

This commit replaces the manual rcu_read_lock() and rcu_read_unlock() pairs
combined with for_each_process() and for_each_process_thread() loops in
the fs/ tree with the for_each_*_rculock() macros. These new macros scope
the RCU read lock to the loop body using scoped_guard().

[Severity: Medium]
Does this code introduce a regression by mixing scope-based cleanup helpers
with goto-based error handling?

The newly introduced for_each_process_rculock() macro expands to use
scoped_guard(rcu). However, __set_oom_adj() still relies on goto-based
cleanup paths earlier in the function:

fs/proc/base.c:__set_oom_adj() {
	// ...
	mutex_lock(&oom_adj_mutex);
	if (legacy) {
		if (oom_adj < task->signal->oom_score_adj &&
				!capable(CAP_SYS_RESOURCE)) {
			err = -EACCES;
			goto err_unlock;
		}
	// ...
err_unlock:
	mutex_unlock(&oom_adj_mutex);
	put_task_struct(task);
	return err;
}

The kernel cleanup subsystem guidelines in include/linux/cleanup.h note
that goto and cleanup helpers should never be mixed in the same function,
as it creates confusing ownership semantics. Could this function either
avoid using the scoped cleanup loop or fully convert the oom_adj_mutex
to a guard() pattern as well?

 			if (same_thread_group(task, p))
 				continue;

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260911075800.491472-1-ye.liu@linux.dev?part=13

在 2026/9/11 16:13, sashiko-bot@kernel.org 写道:

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Potential NULL pointer dereference or Use-After-Free of `folio->mapping` in `collect_procs_file()` due to concurrent truncation.
--

Unrelated to this patch. I will fix it later.

commit 788d1f422c3f19026d9e0d86b550c238607720ed
Author: Ye Liu [off-list ref]

mm/memory-failure: convert process iterator to for_each_process_rculock

This commit replaces the manual rcu_read_lock()/rcu_read_unlock() pairs
combined with for_each_process() loop in mm/memory-failure.c with
for_each_process_rculock(), which scopes the RCU read lock to the loop body
via scoped_guard(rcu).

quoted

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index a8b03e2920ba8..7d93deb1f7b3d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c

[ ... ]

quoted

@@ -589,9 +587,8 @@ static void collect_procs_file(const struct folio *folio,
 	pgoff_t pgoff;
 
 	i_mmap_lock_read(mapping);

[Severity: High]
This is a pre-existing issue, but could this lead to a NULL pointer
dereference or a use-after-free of mapping due to a race with truncation?

In memory_failure(), the folio lock is dropped in hwpoison_user_mappings()
before calling collect_procs(). collect_procs() performs an unlocked check of
!folio->mapping:

static void collect_procs(...)
{
	if (!folio->mapping)
		return;
	...
	else
		collect_procs_file(folio, page, tokill, force_early);
}

If a concurrent truncation removes the folio from the page cache immediately
after this check, folio->mapping becomes NULL. collect_procs_file() then
initializes mapping = folio->mapping and calls i_mmap_lock_read(mapping).

If the compiler performs a second read of folio->mapping, mapping will be
NULL, crashing the kernel on the semaphore acquisition. If the compiler
caches the first read, mapping will point to an address_space whose host
inode may have been concurrently freed, leading to a use-after-free since
the elevated page refcount does not pin the inode and no RCU read lock is
held during the blocking i_mmap_lock_read() call.

quoted

-	rcu_read_lock();
 	pgoff = page_pgoff(folio, page);
-	for_each_process(tsk) {
+	for_each_process_rculock(tsk) {
 		struct task_struct *t = task_early_kill(tsk, force_early);
 		unsigned long addr;

-- 
Thanks,
Ye Liu

在 2026/9/11 16:11, sashiko-bot@kernel.org 写道:

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The commit message incorrectly claims to replace `for_each_thread()` with `for_each_thread_rculock()`, but the code actually replaces `for_each_process()` with `for_each_process_rculock()`.
--

commit 3ac98de6fbc4e97ba4981ef0c4941692c15a9309
Author: Ye Liu [off-list ref]

cpu/hotplug: convert thread iterator to for_each_thread_rculock

This commit replaces a manual rcu_read_lock() and rcu_read_unlock() pair
in clear_tasks_mm_cpumask() with a scoped RCU lock iterator macro.

quoted

cpu/hotplug: convert thread iterator to for_each_thread_rculock
    
Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_thread() loop in kernel/cpu.c with for_each_thread_rculock(),

[Severity: Medium]
Is the commit message accurate regarding the iterator being replaced?

The commit message subject and body describe converting a thread iterator
using for_each_thread() to for_each_thread_rculock(). However, looking at
clear_tasks_mm_cpumask() in the diff:

quoted

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b3c8553d7bd6c..00638d2abc0f6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c

@@ -1254,8 +1254,7 @@ void clear_tasks_mm_cpumask(int cpu)
 	 * full-fledged tasklist_lock.
 	 */
 	WARN_ON(cpu_online(cpu));
-	rcu_read_lock();
-	for_each_process(p) {
+	for_each_process_rculock(p) {

The code actually replaces for_each_process() with for_each_process_rculock().

Could the commit message be updated to match the process iterator actually
used in the patch to avoid confusion during review or bisection?

Sorry, copy error. It should be the following content:

cpu/hotplug: convert process iterator to for_each_process_rculock
    
    Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
    with for_each_process() loop in kernel/cpu.c with for_each_process_rculock(),
    which scopes the RCU read lock to the loop body via scoped_guard(rcu).
    
    No functional change.

-- 
Thanks,
Ye Liu

On Fri, 11 Sep 2026 15:57:57 +0800
Ye Liu [off-list ref] wrote:

From: Ye Liu <liuye@kylinos.cn>

Replace guard(rcu)() combined with for_each_process_thread() loop in
kernel/unwind/deferred.c with for_each_process_thread_rculock(),
which scopes the RCU read lock to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve

On Fri, 11 Sep 2026 15:57:56 +0800
Ye Liu [off-list ref] wrote:

From: Ye Liu <liuye@kylinos.cn>

Replace the manual rcu_read_lock()/rcu_read_unlock() pair combined
with for_each_process_thread() loop in kernel/trace/fgraph.c with
for_each_process_thread_rculock(), which scopes the RCU read lock
to the loop body via scoped_guard(rcu).

No functional change.

Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: SJ Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve