From nobody Wed Dec 17 13:51:26 2025 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 2639734D3A9 for ; Sat, 8 Nov 2025 13:04:28 +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=1762607069; cv=none; b=IcktSWJG3Q+F/rgEDExgMc5U/4OAPiDZzYKubRG4fixlttdIFH8uO3UCANmjlVQPUTyd7s35DtWMzR7dOUm2kq11zCzDYBjaDoGxNI34Ymervqv4ybx0X1KclvR3m0dy87HFLlvT5i+XCmJ0xCKL0GZ2KObt1gR/53xK25mZfh0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762607069; c=relaxed/simple; bh=OzIMCKQb6IkHBqEEfZaauAwluqNBj8C9BUfXJwnA4oY=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=ngxYtwyE6512Fq022nyx3IjwnXWBtCaaC0h3HCx1eDdjDjfAnSLVUa8ODvW3nH3V+7ex9qikimmaRI7PzRrjBeFX0ro8ZtrxLl1USyHDOOxFMwyg5dorNJJdE9mTsQE6mbF3PBgvRj2sR82cGXusr6SygkjRjQX5ttJciFVJS6g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RtvBGNU+; 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="RtvBGNU+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 769D0C116C6; Sat, 8 Nov 2025 13:04:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762607068; bh=OzIMCKQb6IkHBqEEfZaauAwluqNBj8C9BUfXJwnA4oY=; h=Date:From:To:Cc:Subject:From; b=RtvBGNU+4N8hdEO7yzqgXgyJ3o9GX1oCWIxBP4czP3+nF807u47LbIAwkFCAnAvcW v/ya+BgXx/kLu35B0Xa2AgjJQrfE27XZF8usYu+LN+4EyYbFze8zdB86lFVUTCVcXE gTHY+GhS0qgTPAeM1dn/xxH4D2wbDQrYHGDso7FUZENZThuA+VVdDC94cKn2kcUYlD aT5Fyzrp/l/nPYvVFgvdgqCY3Ek8zvF9EAYY4Gbd/e5Z6MYtMmko0shmANlX7xjUhV DHwKRayesoRGUQNefVCn2LUWyks10caync2RuD5AfkwRfT3UPfs27ReD4l2w2dqjMr 0XhtXXJt2B9eA== Date: Sat, 8 Nov 2025 14:04:18 +0100 From: Ingo Molnar To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Will Deacon , Thomas Gleixner , Andrew Morton , Boqun Feng , Waiman Long , Borislav Petkov Subject: [GIT PULL] locking fix Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Linus, Please pull the latest locking/urgent Git tree from: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking-urgent= -2025-11-08 # HEAD: 4cb5ac2626b5704ed712ac1d46b9d89fdfc12c5d futex: Optimize per-cpu= reference counting Fix (well, cut in half) a futex performance regression on PowerPC. Thanks, Ingo ------------------> Peter Zijlstra (1): futex: Optimize per-cpu reference counting kernel/futex/core.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/kernel/futex/core.c b/kernel/futex/core.c index 125804fbb5cb..2e77a6e5c865 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -1680,10 +1680,10 @@ static bool futex_ref_get(struct futex_private_hash= *fph) { struct mm_struct *mm =3D fph->mm; =20 - guard(rcu)(); + guard(preempt)(); =20 - if (smp_load_acquire(&fph->state) =3D=3D FR_PERCPU) { - this_cpu_inc(*mm->futex_ref); + if (READ_ONCE(fph->state) =3D=3D FR_PERCPU) { + __this_cpu_inc(*mm->futex_ref); return true; } =20 @@ -1694,10 +1694,10 @@ static bool futex_ref_put(struct futex_private_hash= *fph) { struct mm_struct *mm =3D fph->mm; =20 - guard(rcu)(); + guard(preempt)(); =20 - if (smp_load_acquire(&fph->state) =3D=3D FR_PERCPU) { - this_cpu_dec(*mm->futex_ref); + if (READ_ONCE(fph->state) =3D=3D FR_PERCPU) { + __this_cpu_dec(*mm->futex_ref); return false; }