This is a note to let you know that I've just added the patch titled
getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()
to the 6.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
getrusage-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand.patch
and it can be found in the queue-6.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From daa694e4137571b4ebec330f9a9b4d54aa8b8089 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Mon, 22 Jan 2024 16:50:50 +0100
Subject: getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand()
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit daa694e4137571b4ebec330f9a9b4d54aa8b8089 upstream.
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/20240122155023.GA26169@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20240122155050.GA26205@xxxxxxxxxx
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reported-by: Dylan Hatch <dylanbhatch@xxxxxxxxxx>
Tested-by: Dylan Hatch <dylanbhatch@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sys.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -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 stable-queue which might be from oleg@xxxxxxxxxx are
queue-6.7/getrusage-move-thread_group_cputime_adjusted-outside-of-lock_task_sighand.patch
queue-6.7/getrusage-use-sig-stats_lock-rather-than-lock_task_sighand.patch
