From patchwork Thu Jun 27 13:37:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Akihiko Odaki X-Patchwork-Id: 13714424 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 7129EC30653 for ; Thu, 27 Jun 2024 13:40:41 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sMpLG-0001Zc-GH; Thu, 27 Jun 2024 09:39:14 -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 1sMpLC-0001VV-7S for qemu-devel@nongnu.org; Thu, 27 Jun 2024 09:39:11 -0400 Received: from mail-pl1-x633.google.com ([2607:f8b0:4864:20::633]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1sMpL9-0006Uz-H0 for qemu-devel@nongnu.org; Thu, 27 Jun 2024 09:39:09 -0400 Received: by mail-pl1-x633.google.com with SMTP id d9443c01a7336-1faad409ca7so4181175ad.1 for ; Thu, 27 Jun 2024 06:39:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=daynix-com.20230601.gappssmtp.com; s=20230601; t=1719495545; x=1720100345; 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=6MgmHQG/2ylhpi7rbXo5VyylZZdoY/6uUXCCV6pKunI=; b=3YEktQY4Cf9mZ6ojcJDmxaq+/SRt+RI0N6N1Vsn4KC9bV+AObK7oZWXsZoPohCBynS B474C4l4Gm4uFKO8qjb941adW3fuD4TNFGUq4BKrO3mMwtO8TPIBuQs2k87RpeWes9c/ HNRmpoL3bEec3/Q0D8EkADytvqC646u2UQ9nyzDKqxMlC71sZ9Q9iJyDwAxscxpnjLSA wqh+94UWPrOBNfS+492EmEtqWrgu0QVN2snPVx8dGFC/MwJZdmLZTRStjMnLO+dhTmCB R3+ZAd0s8QuBZbyh9F1b6ykYQ4uxwAi2/SHmKE5IX86qYGm9kGJaHddVeoe8q/c/hl9W YqWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1719495545; x=1720100345; 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=6MgmHQG/2ylhpi7rbXo5VyylZZdoY/6uUXCCV6pKunI=; b=a7cibJZBiq30t8nrzDYf2jgftOT4amw00UOHNiTKHDOTXMMSNClrIH9QOSq8v59FcP pHX7m/S4NQecHWu+Zu9kDgxL9mQDD7WmPsFSV4q/JkBxVZxZyJdW0HNri7CT+mb+X2qA qIuSCkF1UuHaLOstzh3wnCMq2VYU14SQ8GC/6VfQb+wXqJxWue2a0Wa5vs4k7TRJsEbT 6G4B8VigR5rczWt1Sn+mhrkN1YWQrFqzVNObLQIkZLiEsLZWjNZ4jCmWSgiPmEcIfG39 M39xYNBhBUOmdqy+O3f75Hh0JXOJQ+S82QcSJCR39WjWl2zmhsQomLWcRIcwjIrqVXDx CNzw== X-Gm-Message-State: AOJu0Ywh96dCoBP8gXXM1/nxCP2NrqTW36JCIBIC/vbjE6bH+AakFSz1 Bt5aOPl7pQUAxAByKLNcNdJwkFbNfizJfE2W0g1SXgKGIbmQzmyBDCn+NlYcSr8= X-Google-Smtp-Source: AGHT+IEOQ/m6W0EaVrS87L9pcyV7z7eXSKdvdlz5a1XfK+ZrnOVnl6VAIXcrZ4tj5pOxawKYTrGRaA== X-Received: by 2002:a17:903:228a:b0:1f6:dccd:c6db with SMTP id d9443c01a7336-1faac2df4b0mr24948755ad.30.1719495545496; Thu, 27 Jun 2024 06:39:05 -0700 (PDT) Received: from localhost ([2400:4050:a840:1e00:9ac7:6d57:2b16:6932]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-1faac9791fdsm13201035ad.127.2024.06.27.06.39.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Jun 2024 06:39:05 -0700 (PDT) From: Akihiko Odaki Date: Thu, 27 Jun 2024 22:37:52 +0900 Subject: [PATCH v2 09/15] memory: Do not create circular reference with subregion MIME-Version: 1.0 Message-Id: <20240627-san-v2-9-750bb0946dbd@daynix.com> References: <20240627-san-v2-0-750bb0946dbd@daynix.com> In-Reply-To: <20240627-san-v2-0-750bb0946dbd@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 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=2607:f8b0:4864:20::633; envelope-from=akihiko.odaki@daynix.com; helo=mail-pl1-x633.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 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 A memory region does not use their own reference counters, but instead piggybacks on another QOM object, "owner" (unless the owner is not the memory region itself). When creating a subregion, a new reference to the owner of the container must be created. However, if the subregion is owned by the same QOM object, this result in a self-reference, and make the owner immortal. Avoid such a self-reference. Signed-off-by: Akihiko Odaki --- system/memory.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/system/memory.c b/system/memory.c index 74cd73ebc78b..949f5016a68d 100644 --- a/system/memory.c +++ b/system/memory.c @@ -2638,7 +2638,10 @@ static void memory_region_update_container_subregions(MemoryRegion *subregion) memory_region_transaction_begin(); - memory_region_ref(subregion); + if (mr->owner != subregion->owner) { + memory_region_ref(subregion); + } + QTAILQ_FOREACH(other, &mr->subregions, subregions_link) { if (subregion->priority >= other->priority) { QTAILQ_INSERT_BEFORE(other, subregion, subregions_link); @@ -2696,7 +2699,11 @@ void memory_region_del_subregion(MemoryRegion *mr, assert(alias->mapped_via_alias >= 0); } QTAILQ_REMOVE(&mr->subregions, subregion, subregions_link); - memory_region_unref(subregion); + + if (mr->owner != subregion->owner) { + memory_region_unref(subregion); + } + memory_region_update_pending |= mr->enabled && subregion->enabled; memory_region_transaction_commit(); }