From patchwork Fri Aug 23 06:13:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Akihiko Odaki X-Patchwork-Id: 13774624 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 03534C531DC for ; Fri, 23 Aug 2024 06:14:35 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1shNYk-0003J5-SR; Fri, 23 Aug 2024 02:14:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1shNYj-0003BR-0s for qemu-devel@nongnu.org; Fri, 23 Aug 2024 02:14:05 -0400 Received: from mail-oa1-x33.google.com ([2001:4860:4864:20::33]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1shNYg-0003Bq-Fd for qemu-devel@nongnu.org; Fri, 23 Aug 2024 02:14:04 -0400 Received: by mail-oa1-x33.google.com with SMTP id 586e51a60fabf-273cf9bbb3eso977683fac.1 for ; Thu, 22 Aug 2024 23:14:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=daynix-com.20230601.gappssmtp.com; s=20230601; t=1724393641; x=1724998441; darn=nongnu.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=TqGUJw12uTAbvh8M71+t9HGKJ1QBUKeYyyQ+O3KoOC0=; b=iq4lraWW0+JKVzVOGOjeFPScRb2883/QCyZJvhlo5c+6q+wDiJueZWzoKkgT2fklXG Z+3gQTUSnd6Hyqf5l+vWNWCX82rHDpjnperHnLnTsqpTS6/R8wH3p9UB+NOmk6QU6vXz JzDteJJ0ajK56vbR+gENxcxlG4P7xFWq9AHKFCHd17jaUXn7+ejRv8SUh4ScwfpYsO4B cBcBOvfUgHh0PN52R0v2uTHKayPWhUyCEZYSeO5nC0gfx2gh556F2Arx/c9+XVdhhzWo Z22OLiTLLlDRGbCQqwakXVgEDL7EP5Mk1X6qqYiFc0Y9VNcK3537dFFGtfN2WKRHk6x2 PHiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1724393641; x=1724998441; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=TqGUJw12uTAbvh8M71+t9HGKJ1QBUKeYyyQ+O3KoOC0=; b=A4E5/VlNTA8ZTubCbTTpWteSu7cpdwen0ZewwCJlp5Wn5x5BsiyrV5yf2AH3kELa2U emUXDGNX5GL+FKuUR7eWegrhnEIUKtLdmp+rUkJ0bUmQOGsL1tEpGKCiriINbDFpCT3z 0R/vDrocHqeqe9YcwYXt9DqUTwoCNWlBEQB1vKmiNlJL8SB7hhLxBcCRaU4OtNBmisc0 p+iFBvWLJ4wbxA2rsfWEMfv8O1OaliOBVwTDprXCxYLDbgtQSrOU540nnhNY9p/DW6wM F7m6aRaj+4y8XY5kD5BWEmFLy/RYE7SDGmzGDp7LAeIPiB2E502GEplUvvrokFfxPTvQ wpng== X-Gm-Message-State: AOJu0YwZNnyxmfsQgTGJmad1vyDW34+aXqOEHP5vzQ8o/sH/XjvUbajs b9Eeywo42KCS11x0GkJKEUmtaO5XIaiRWSKrAZJ4rdJu6c+NsYcuWsHYxfmV89c= X-Google-Smtp-Source: AGHT+IHAfk6dVYsonq3Hlwrg808+TTvRceTk+pc5LzEGFXYQT7ovRTiKEte4g/HUA21ToYZjiMQeOQ== X-Received: by 2002:a05:6870:5587:b0:270:129f:8e65 with SMTP id 586e51a60fabf-273e66589c9mr1134333fac.34.1724393641047; Thu, 22 Aug 2024 23:14:01 -0700 (PDT) Received: from localhost ([157.82.207.23]) by smtp.gmail.com with UTF8SMTPSA id d2e1a72fcca58-71434335fe1sm2302862b3a.200.2024.08.22.23.13.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 22 Aug 2024 23:14:00 -0700 (PDT) From: Akihiko Odaki Date: Fri, 23 Aug 2024 15:13:11 +0900 Subject: [PATCH v4 6/7] memory: Do not create circular reference with subregion MIME-Version: 1.0 Message-Id: <20240823-san-v4-6-a24c6dfa4ceb@daynix.com> References: <20240823-san-v4-0-a24c6dfa4ceb@daynix.com> In-Reply-To: <20240823-san-v4-0-a24c6dfa4ceb@daynix.com> To: Eduardo Habkost , Marcel Apfelbaum , =?utf-8?q?Philippe_Mathieu-?= =?utf-8?q?Daud=C3=A9?= , Yanan Wang , John Snow , BALATON Zoltan , Jiaxun Yang , Nicholas Piggin , Daniel Henrique Barboza , David Gibson , Harsh Prateek Bora , Alexey Kardashevskiy , "Michael S. Tsirkin" , =?utf-8?q?Alex_Benn=C3=A9e?= , Peter Xu , Fabiano Rosas , Paolo Bonzini , David Hildenbrand , Thomas Huth , Laurent Vivier , Peter Maydell Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, qemu-ppc@nongnu.org, Akihiko Odaki X-Mailer: b4 0.14-dev-fd6e3 Received-SPF: none client-ip=2001:4860:4864:20::33; envelope-from=akihiko.odaki@daynix.com; helo=mail-oa1-x33.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org memory_region_update_container_subregions() used to call memory_region_ref(), which creates a reference to the owner of the subregion, on behalf of the owner of the container. This results in a circular reference if the subregion and container have the same owner. memory_region_ref() creates a reference to the owner instead of the memory region to match the lifetime of the owner and memory region. We do not need such a hack if the subregion and container have the same owner because the owner will be alive as long as the container is. Therefore, create a reference to the subregion itself instead ot its owner in such a case; the reference to the subregion is still necessary to ensure that the subregion gets finalized after the container. Signed-off-by: Akihiko Odaki --- system/memory.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/system/memory.c b/system/memory.c index 5e6eb459d5de..e4d3e9d1f427 100644 --- a/system/memory.c +++ b/system/memory.c @@ -2612,7 +2612,9 @@ static void memory_region_update_container_subregions(MemoryRegion *subregion) memory_region_transaction_begin(); - memory_region_ref(subregion); + object_ref(mr->owner == subregion->owner ? + OBJECT(subregion) : subregion->owner); + QTAILQ_FOREACH(other, &mr->subregions, subregions_link) { if (subregion->priority >= other->priority) { QTAILQ_INSERT_BEFORE(other, subregion, subregions_link); @@ -2670,7 +2672,9 @@ void memory_region_del_subregion(MemoryRegion *mr, assert(alias->mapped_via_alias >= 0); } QTAILQ_REMOVE(&mr->subregions, subregion, subregions_link); - memory_region_unref(subregion); + object_unref(mr->owner == subregion->owner ? + OBJECT(subregion) : subregion->owner); + memory_region_update_pending |= mr->enabled && subregion->enabled; memory_region_transaction_commit(); }