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 gather the threads/children stats") Cc: stable@vger.kernel.org [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.

--- 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 2cb01aaa6718..2ff568dc5838 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 pid_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));