Re: [PATCH 5.15] fs/proc: do_task_stat: use __for_each_thread()

Hi,

+ stable

On 05/06/25 19:37, Heyne, Maximilian wrote:

From: Oleg Nesterov oleg@redhat.com

[ Upstream commit 7904e53ed5a20fc678c01d5d1b07ec486425bb6a ]

do/while_each_thread should be avoided when possible.

Link: https://lkml.kernel.org/r/20230909164501.GA11581@redhat.com Signed-off-by: Oleg Nesterov oleg@redhat.com Cc: Eric W. Biederman ebiederm@xmission.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Stable-dep-of: 7601df8031fd ("fs/proc: do_task_stat: use sig->stats_lock to=ather the threads/children stats") [mheyne: adjusted context] Signed-off-by: Maximilian Heyne mheyne@amazon.de

---

Compile-tested only. We're seeing soft lock-ups with 5.10.237 because of the backport of commit 4fe85bdaabd6 ("fs/proc: do_task_stat: use sig->stats_lock to gather the threads/children stats"). I'm assuming this is broken on 5.15 too.

Note: We saw this as well after backporting the above mentioned commit from 5.15.y and your backport resolves it for us as well on 5.15.y based branch.

Thanks, Harshit

---

fs/proc/array.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c index 2cb01aaa67187..2ff568dc58387 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -530,18 +530,18 @@ static int do_task_stat(struct seq_file *m, struct pi=_namespace *ns, cgtime = sig->cgtime; = if (whole) {

• 	struct task_struct *t = task;
  

• 	struct task_struct *t;
  

  = min_flt = sig->min_flt; maj_flt = sig->maj_flt; gtime = sig->gtime; = rcu_read_lock();

• 	do {
  

• 	__for_each_thread(sig, t) {
  	min_flt += t->min_flt;
  	maj_flt += t->maj_flt;
  	gtime += task_gtime(t);
  

• 	} while_each_thread(task, t);
  

• 	}
  rcu_read_unlock();
  

  } } while (need_seqretry(&sig->stats_lock, seq));

-- =2.47.1

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