The quilt patch titled
Subject: memcg: mm_update_next_owner: move for_each_thread() into try_to_set_owner()
has been removed from the -mm tree. Its filename was
memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: memcg: mm_update_next_owner: move for_each_thread() into try_to_set_owner()
Date: Wed, 26 Jun 2024 17:29:30 +0200
mm_update_next_owner() checks the children / real_parent->children to
avoid the "everything else" loop in the likely case, but this won't work
if a child/sibling has a zombie leader with ->mm == NULL.
Move the for_each_thread() logic into try_to_set_owner(), if nothing else
this makes the children/siblings/everything searches more consistent.
Link: https://lkml.kernel.org/r/20240626152930.GA17936@xxxxxxxxxx
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Jinliang Zheng <alexjlzheng@xxxxxxxxxxx>
Cc: Mateusz Guzik <mjguzik@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Tycho Andersen <tandersen@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/exit.c | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
--- a/kernel/exit.c~memcg-mm_update_next_owner-move-for_each_thread-into-try_to_set_owner
+++ a/kernel/exit.c
@@ -440,7 +440,7 @@ static void coredump_task_exit(struct ta
#ifdef CONFIG_MEMCG
/* drops tasklist_lock if succeeds */
-static bool try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm)
+static bool __try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm)
{
bool ret = false;
@@ -456,12 +456,28 @@ static bool try_to_set_owner(struct task
return ret;
}
+static bool try_to_set_owner(struct task_struct *g, struct mm_struct *mm)
+{
+ struct task_struct *t;
+
+ for_each_thread(g, t) {
+ struct mm_struct *t_mm = READ_ONCE(t->mm);
+ if (t_mm == mm) {
+ if (__try_to_set_owner(t, mm))
+ return true;
+ } else if (t_mm)
+ break;
+ }
+
+ return false;
+}
+
/*
* A task is exiting. If it owned this mm, find a new owner for the mm.
*/
void mm_update_next_owner(struct mm_struct *mm)
{
- struct task_struct *c, *g, *p = current;
+ struct task_struct *g, *p = current;
/*
* If the exiting or execing task is not the owner, it's
@@ -483,19 +499,17 @@ void mm_update_next_owner(struct mm_stru
/*
* Search in the children
*/
- list_for_each_entry(c, &p->children, sibling) {
- if (c->mm == mm && try_to_set_owner(c, mm))
+ list_for_each_entry(g, &p->children, sibling) {
+ if (try_to_set_owner(g, mm))
goto ret;
}
-
/*
* Search in the siblings
*/
- list_for_each_entry(c, &p->real_parent->children, sibling) {
- if (c->mm == mm && try_to_set_owner(c, mm))
+ list_for_each_entry(g, &p->real_parent->children, sibling) {
+ if (try_to_set_owner(g, mm))
goto ret;
}
-
/*
* Search through everything else, we should not get here often.
*/
@@ -504,14 +518,8 @@ void mm_update_next_owner(struct mm_stru
break;
if (g->flags & PF_KTHREAD)
continue;
- for_each_thread(g, c) {
- struct mm_struct *c_mm = READ_ONCE(c->mm);
- if (c_mm == mm) {
- if (try_to_set_owner(c, mm))
- goto ret;
- } else if (c_mm)
- break;
- }
+ if (try_to_set_owner(g, mm))
+ goto ret;
}
read_unlock(&tasklist_lock);
/*
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
zap_pid_ns_processes-dont-send-sigkill-to-sub-threads.patch
coredump-simplify-zap_process.patch
