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getrusage-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand.patch removed from -mm tree

merged mm-hotfixes-stable Andrew Morton 1 participant 1 message Feb 8, 2024 Stable branch

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The quilt patch titled
Subject: getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()
has been removed from the -mm tree. Its filename was
getrusage-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Oleg Nesterov <[email protected]>
Subject: getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()
Date: Mon, 22 Jan 2024 16:50:50 +0100

Patch series "getrusage: use sig->stats_lock", v2.

This patch (of 2):

thread_group_cputime() does its own locking, we can safely shift thread_group_cputime_adjusted() which does another for_each_thread loop outside of ->siglock protected section.

This is also preparation for the next patch which changes getrusage() to use stats_lock instead of siglock, thread_group_cputime() takes the same lock. With the current implementation recursive read_seqbegin_or_lock() is fine, thread_group_cputime() can't enter the slow mode if the caller holds stats_lock, yet this looks more safe and better performance-wise.

Link https://lkml.kernel.org/r/[email protected] open here
Link https://lkml.kernel.org/r/[email protected] open here
Signed-off-by Oleg Nesterov <[email protected]>
Reported-by Dylan Hatch <[email protected]>
Tested-by Dylan Hatch <[email protected]>
Cc Eric W. Biederman <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>

---

 kernel/sys.c |   36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)
kernel/sys.c renamed from kernel/sys.c~getrusage-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand +20 -16
@@ -1785,17 +1785,19 @@ void getrusage(struct task_struct *p, in
 	struct task_struct *t;
 	unsigned long flags;
 	u64 tgutime, tgstime, utime, stime;
-	unsigned long maxrss = 0;
+	unsigned long maxrss;
+	struct mm_struct *mm;
 	struct signal_struct *sig = p->signal;
 
-	memset((char *)r, 0, sizeof (*r));
+	memset(r, 0, sizeof(*r));
 	utime = stime = 0;
+	maxrss = 0;
 
 	if (who == RUSAGE_THREAD) {
 		task_cputime_adjusted(current, &utime, &stime);
 		accumulate_thread_rusage(p, r);
 		maxrss = sig->maxrss;
-		goto out;
+		goto out_thread;
 	}
 
 	if (!lock_task_sighand(p, &flags))

@@ -1819,9 +1821,6 @@ void getrusage(struct task_struct *p, in
 		fallthrough;
 
 	case RUSAGE_SELF:
-		thread_group_cputime_adjusted(p, &tgutime, &tgstime);
-		utime += tgutime;
-		stime += tgstime;
 		r->ru_nvcsw += sig->nvcsw;
 		r->ru_nivcsw += sig->nivcsw;
 		r->ru_minflt += sig->min_flt;

@@ -1839,19 +1838,24 @@ void getrusage(struct task_struct *p, in
 	}
 	unlock_task_sighand(p, &flags);
 
-out:
-	r->ru_utime = ns_to_kernel_old_timeval(utime);
-	r->ru_stime = ns_to_kernel_old_timeval(stime);
-
-	if (who != RUSAGE_CHILDREN) {
-		struct mm_struct *mm = get_task_mm(p);
+	if (who == RUSAGE_CHILDREN)
+		goto out_children;
 
-		if (mm) {
-			setmax_mm_hiwater_rss(&maxrss, mm);
-			mmput(mm);
-		}
+	thread_group_cputime_adjusted(p, &tgutime, &tgstime);
+	utime += tgutime;
+	stime += tgstime;
+
+out_thread:
+	mm = get_task_mm(p);
+	if (mm) {
+		setmax_mm_hiwater_rss(&maxrss, mm);
+		mmput(mm);
 	}
+
+out_children:
 	r->ru_maxrss = maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */
+	r->ru_utime = ns_to_kernel_old_timeval(utime);
+	r->ru_stime = ns_to_kernel_old_timeval(stime);
 }
 
 SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru)

_

Patches currently in -mm which might be from [email protected] are

ptrace_attach-shift-sendsigstop-into-ptrace_set_stopped.patch