2023-05-15 06:21:14

by Shawn Wang

Subject: [PATCH v2] x86/resctrl: Only show tasks' pid in current pid namespace

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.

Link: https://lore.kernel.org/all/[email protected]/
Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files")
Signed-off-by: Shawn Wang <[email protected]>
Tested-by: Reinette Chatre <[email protected]>
Acked-by: Reinette Chatre <[email protected]>
---
Changes since v1:
- Update commit message and commit tags.

arch/x86/kernel/cpu/resctrl/rdtgroup.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 6ad33f355861..61cdd9b1bb6d 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -726,11 +726,15 @@ 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();
}
--
2.31.1

2023-05-16 19:26:06

by Fenghua Yu

Subject: Re: [PATCH v2] x86/resctrl: Only show tasks' pid in current pid namespace

On 5/14/23 23:04, Shawn Wang wrote:
> 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.
>
> Link: https://lore.kernel.org/all/[email protected]/
> Fixes: e02737d5b826 ("x86/intel_rdt: Add tasks files")
> Signed-off-by: Shawn Wang <[email protected]>
> Tested-by: Reinette Chatre <[email protected]>
> Acked-by: Reinette Chatre <[email protected]>

Acked-by: Fenghua Yu <[email protected]>

Thanks.

-Fenghua