The patch titled Subject: exit: wait_task_zombie: kill the no longer necessary spin_lock_irq(siglock) has been added to the -mm mm-hotfixes-unstable branch. Its filename is exit-wait_task_zombie-kill-the-no-longer-necessary-spin_lock_irqsiglock.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: Oleg Nesterov oleg@redhat.com Subject: exit: wait_task_zombie: kill the no longer necessary spin_lock_irq(siglock) Date: Tue, 23 Jan 2024 16:34:00 +0100
After the recent changes nobody use siglock to read the values protected by stats_lock, we can kill spin_lock_irq(¤t->sighand->siglock) and update the comment.
With this patch only __exit_signal() and thread_group_start_cputime() take stats_lock under siglock.
Link: https://lkml.kernel.org/r/20240123153359.GA21866@redhat.com Signed-off-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Dylan Hatch dylanbhatch@google.com Cc: Eric W. Biederman ebiederm@xmission.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
kernel/exit.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)
--- a/kernel/exit.c~exit-wait_task_zombie-kill-the-no-longer-necessary-spin_lock_irqsiglock +++ a/kernel/exit.c @@ -1127,17 +1127,14 @@ static int wait_task_zombie(struct wait_ * and nobody can change them. * * psig->stats_lock also protects us from our sub-threads - * which can reap other children at the same time. Until - * we change k_getrusage()-like users to rely on this lock - * we have to take ->siglock as well. + * which can reap other children at the same time. * * We use thread_group_cputime_adjusted() to get times for * the thread group, which consolidates times for all threads * in the group including the group leader. */ thread_group_cputime_adjusted(p, &tgutime, &tgstime); - spin_lock_irq(¤t->sighand->siglock); - write_seqlock(&psig->stats_lock); + write_seqlock_irq(&psig->stats_lock); psig->cutime += tgutime + sig->cutime; psig->cstime += tgstime + sig->cstime; psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime; @@ -1160,8 +1157,7 @@ static int wait_task_zombie(struct wait_ psig->cmaxrss = maxrss; task_io_accounting_add(&psig->ioac, &p->ioac); task_io_accounting_add(&psig->ioac, &sig->ioac); - write_sequnlock(&psig->stats_lock); - spin_unlock_irq(¤t->sighand->siglock); + write_sequnlock_irq(&psig->stats_lock); }
if (wo->wo_rusage) _
Patches currently in -mm which might be from oleg@redhat.com are
getrusage-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand.patch getrusage-use-sig-stats_lock-rather-than-lock_task_sighand.patch fs-proc-do_task_stat-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand.patch fs-proc-do_task_stat-use-sig-stats_lock-to-gather-the-threads-children-stats.patch exit-wait_task_zombie-kill-the-no-longer-necessary-spin_lock_irqsiglock.patch ptrace_attach-shift-sendsigstop-into-ptrace_set_stopped.patch