From nobody Sun Oct 5 00:09:23 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 66DEB1DC9B8 for ; Mon, 11 Aug 2025 14:05:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754921137; cv=none; b=YI9bGpZ90lbWqDKiNZRFGYd2kbV4etPanPlFWTmbH+poBALSJIFKe2HtthvnuVsYHcVYVPL+Uq8C6qTh5VIiT48m8yXidT+mHKlMsTFY8IJUP0Uw/+yPaShQIsVUcqSGXFKS8qTuLZgDvmYOHEh9GhYslwYmX3/Wbgw/zp4MW6Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754921137; c=relaxed/simple; bh=tY3GvRfU+ZbC5r18UWr26Sk5eER0Z1yHXOrsLc2TgUs=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=DL6Bk1TxozYu45i1h2qHy3X9tj40STz9sTToCWlC3OVGVNK8cryba6wosYNnl2a9+KmpRbXQVlV9ZV3V2oiIfLdXXTnUXejwqH9jH5LQkNJHRl5jEbIacvA8csQ9o2U5E1euDyBJgFSakrxvZSHzcqw4WGYyFlJ347RXmUwWiVs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=GjlkA7X8; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GjlkA7X8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1754921133; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=Xnw1x9It7MHX1ft7a9iEuo8H6z86r7iWayv7jAKJfN4=; b=GjlkA7X87x3nstY7l/ytgc6j7nRcror6RDOEjbukm/gqrtoWt2uLjpRR8f5XH7bxYdRqV5 hNMkwiCdduEsQl7xIufClpw47oOFv+3vsKXBxmbxlCzgYQ7u4p1R5UTsXCnl/kdJ350zAT YNuxC2X919lRpJTrTAb8XiY3HxF3l/0= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-272-C_URpHXMMPiN2Bp2WfYQbQ-1; Mon, 11 Aug 2025 10:05:27 -0400 X-MC-Unique: C_URpHXMMPiN2Bp2WfYQbQ-1 X-Mimecast-MFC-AGG-ID: C_URpHXMMPiN2Bp2WfYQbQ_1754921124 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BEEFF1869ADD; Mon, 11 Aug 2025 14:03:35 +0000 (UTC) Received: from llong-thinkpadp16vgen1.westford.csb (unknown [10.22.89.185]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2CBAC19560AB; Mon, 11 Aug 2025 14:03:32 +0000 (UTC) From: Waiman Long To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , =?UTF-8?q?Andr=C3=A9=20Almeida?= , Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Waiman Long Subject: [PATCH v2] futex: Use user_write_access_begin/_end() in futex_put_value() Date: Mon, 11 Aug 2025 10:03:24 -0400 Message-ID: <20250811140324.321751-1-longman@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" Commit cec199c5e39b ("futex: Implement FUTEX2_NUMA") introduces a new futex_put_value() helper function to write a value to the given user address. However, it uses user_read_access_begin() before the write. For arches that differentiate between read and write accesses, like powerpc, futex_put_value() fails with a -EFAULT return value. Fix that by using the user_write_access_begin/user_write_access_end() pair. Fixes: cec199c5e39b ("futex: Implement FUTEX2_NUMA") Signed-off-by: Waiman Long --- kernel/futex/futex.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index c74eac572acd..ebe9e755b3b5 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -319,10 +319,10 @@ static __always_inline int futex_put_value(u32 val, u= 32 __user *to) { if (can_do_masked_user_access()) to =3D masked_user_access_begin(to); - else if (!user_read_access_begin(to, sizeof(*to))) + else if (!user_write_access_begin(to, sizeof(*to))) return -EFAULT; unsafe_put_user(val, to, Efault); - user_read_access_end(); + user_write_access_end(); return 0; Efault: user_read_access_end(); --=20 2.50.1