Patch "x86/resctrl: Only show tasks' pid in current pid namespace" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    x86/resctrl: Only show tasks' pid in current pid namespace

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-resctrl-only-show-tasks-pid-in-current-pid-names.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2998ac05b3d91d2d6eefb6428647f8668e5b752e
Author: Shawn Wang <shawnwang@xxxxxxxxxxxxxxxxx>
Date:   Mon May 15 14:04:48 2023 +0800

    x86/resctrl: Only show tasks' pid in current pid namespace
    
    [ Upstream commit 2997d94b5dd0e8b10076f5e0b6f18410c73e28bd ]
    
    When writing a task id to the "tasks" file in an rdtgroup,
    rdtgroup_tasks_write() treats the pid as a number in the current pid
    namespace. But when reading the "tasks" file, rdtgroup_tasks_show() shows
    the list of global pids from the init namespace, which is confusing and
    incorrect.
    
    To be more robust, let the "tasks" file only show pids in the current pid
    namespace.
    
    Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files")
    Signed-off-by: Shawn Wang <shawnwang@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
    Acked-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
    Acked-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
    Tested-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
    Link: https://lore.kernel.org/all/20230116071246.97717-1-shawnwang@xxxxxxxxxxxxxxxxx/
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 9de55fd77937c..91016bb18d4f9 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -715,11 +715,15 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
 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) {
-		if (is_closid_match(t, r) || is_rmid_match(t, r))
-			seq_printf(s, "%d\n", t->pid);
+		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();
 }