From nobody Sun Feb 8 14:37:51 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A5D61A1E34; Wed, 13 Mar 2024 17:05:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710349516; cv=none; b=QDTC1A5ogcuUUhItIIzK3QXbR3UsAq9d796V3jCvpZ7PJ0h1Ke+DWuKNL5OtuIQwCd3QunG55bq5DRRcyLViGYHdnj3iwf8JUJpdmM+QOhWBhm3jSaVGNUusPVUWJafGQRmOddhGDSd5pTktmCdKgkMMhbWX0QP9gKCy4q5ytaU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710349516; c=relaxed/simple; bh=D33qK3iC2lTGGcA6eSg3iDpe+4bzMfIi9a7UvNyKLuc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PEbIlclIgCttg27NjWYiiNFkYRDwDmkVJaobVSf7AAq9Lpgyhv6KaByFYwPqsFlX0TPFO+33C3Kh2Sr3mDse7xIMoL2vcYHoah7sxaTOw5FhVnH6rOflt30g61GxYmiM2znXa74uJdoAtuXaPHv/AUKiM8AfkSNSwYt6nHDXN0k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=abKAUvgv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="abKAUvgv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 222BCC433F1; Wed, 13 Mar 2024 17:05:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710349516; bh=D33qK3iC2lTGGcA6eSg3iDpe+4bzMfIi9a7UvNyKLuc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=abKAUvgvtdShlzZigAsAdELg0pXot7S5WeWrQ8qJl9/pFc7USfatuq6Fv7DWF/gvF ZypzKBtkfIuS15qBg27+F15UjpTvAHvAchg1i5T8cyxAR3CcjZh+huIgsHtTRbLZei NIIg2c5WVjxPHmasVJ8uVR+SNAOosywlD53KOs4jdsuigMWFYso/oagiCmru4hQ/eR mdPRhp75CvEoKzl4+ez2bEJiL4AB3p4gz2l66ZZr413rrUHRdxPDTziK9+tOK5gQFQ 11nOhdYOfGwghUfFToDCK4UC2rMJmTd+06kdSEh2UvTi/dlUy/KdiE0i/uxTgJSEJV q+b8Wjadk6+Mg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Oleg Nesterov , Dylan Hatch , "Eric W . Biederman" , Andrew Morton , Sasha Levin Subject: [PATCH 4.19 34/41] getrusage: move thread_group_cputime_adjusted() outside of lock_task_sighand() Date: Wed, 13 Mar 2024 13:04:28 -0400 Message-ID: <20240313170435.616724-35-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240313170435.616724-1-sashal@kernel.org> References: <20240313170435.616724-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.310-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.19.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.19.310-rc1 X-KernelTest-Deadline: 2024-03-15T17:04+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Oleg Nesterov [ Upstream commit daa694e4137571b4ebec330f9a9b4d54aa8b8089 ] 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@redhat.com Link: https://lkml.kernel.org/r/20240122155050.GA26205@redhat.com Signed-off-by: Oleg Nesterov Reported-by: Dylan Hatch Tested-by: Dylan Hatch Cc: Eric W. Biederman Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/sys.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index d0d4f4c586518..ab621d7837c97 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1717,17 +1717,19 @@ void getrusage(struct task_struct *p, int who, stru= ct rusage *r) struct task_struct *t; unsigned long flags; u64 tgutime, tgstime, utime, stime; - unsigned long maxrss =3D 0; + unsigned long maxrss; + struct mm_struct *mm; struct signal_struct *sig =3D p->signal; =20 - memset((char *)r, 0, sizeof (*r)); + memset(r, 0, sizeof(*r)); utime =3D stime =3D 0; + maxrss =3D 0; =20 if (who =3D=3D RUSAGE_THREAD) { task_cputime_adjusted(current, &utime, &stime); accumulate_thread_rusage(p, r); maxrss =3D sig->maxrss; - goto out; + goto out_thread; } =20 if (!lock_task_sighand(p, &flags)) @@ -1750,9 +1752,6 @@ void getrusage(struct task_struct *p, int who, struct= rusage *r) break; =20 case RUSAGE_SELF: - thread_group_cputime_adjusted(p, &tgutime, &tgstime); - utime +=3D tgutime; - stime +=3D tgstime; r->ru_nvcsw +=3D sig->nvcsw; r->ru_nivcsw +=3D sig->nivcsw; r->ru_minflt +=3D sig->min_flt; @@ -1772,19 +1771,24 @@ void getrusage(struct task_struct *p, int who, stru= ct rusage *r) } unlock_task_sighand(p, &flags); =20 -out: - r->ru_utime =3D ns_to_kernel_old_timeval(utime); - r->ru_stime =3D ns_to_kernel_old_timeval(stime); + if (who =3D=3D RUSAGE_CHILDREN) + goto out_children; =20 - if (who !=3D RUSAGE_CHILDREN) { - struct mm_struct *mm =3D get_task_mm(p); + thread_group_cputime_adjusted(p, &tgutime, &tgstime); + utime +=3D tgutime; + stime +=3D tgstime; =20 - if (mm) { - setmax_mm_hiwater_rss(&maxrss, mm); - mmput(mm); - } +out_thread: + mm =3D get_task_mm(p); + if (mm) { + setmax_mm_hiwater_rss(&maxrss, mm); + mmput(mm); } + +out_children: r->ru_maxrss =3D maxrss * (PAGE_SIZE / 1024); /* convert pages to KBs */ + r->ru_utime =3D ns_to_kernel_old_timeval(utime); + r->ru_stime =3D ns_to_kernel_old_timeval(stime); } =20 SYSCALL_DEFINE2(getrusage, int, who, struct rusage __user *, ru) --=20 2.43.0