From mboxrd@z Thu Jan 1 00:00:00 1970 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.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 6CD14D2ECEF for ; Mon, 19 Jan 2026 23:02:15 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4dw5ZC63pFz2xqL; Tue, 20 Jan 2026 10:02:11 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=172.234.252.31 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1768863731; cv=none; b=fGaUfDoU/TVE3hj6JGb39vLnrzLww3ar0hWmWQ6QH4N9k2DmRv0+UmhLqlSZ75bNwklX1FvhaquFXV0K2VZA1DS3q4mCtYG4RYSGgV+YkIwha1wCX3E0BhIUjiiy0r7fD7oMKabRRcU9UxV/6N77oBgE+yMv8O0DkfsndonuuPQ3IO8brl0xewb1ZSLRpwWN2oCSTZQdikYQThnc19ybb09/GP7nJlYKQCmTpWFW6iO2E537vz+Lt/OYofYTS//iKSoiPoSmu3Y6rsvq2bW7TuINg4i/cdyZAAGnJkP/cbhUfxKTayt8+5nd5qgOvCJCvGG58tkBRZ27Cmtbp56mUg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1768863731; c=relaxed/relaxed; bh=OGlr4CR3HE26RPwTICbiLHyl58bRcW9pkYQf743lRCQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mDO97D3H6l+RP8xcxGdYyT/p1RuN6rYbFjhqd1wdqm1Kbr9+dDF8jSW0Sqm2ksY9MJs21hiYS6cenr+jkUkmVQAGKPXiE8h6b6hpA1SCuZM57ybAJRkX1jqw6BT+0g4mZAXsUnH4lnvtUgIKwEvQFHtysh24diQzU+ZqoxsLD+zOpXoPZvRULydUsVdDtiQQvaqU0TNbX1VuLAIG67eRW1C827gOhbvsagYac/msg81DCVSiBiQkoqViD+iJjWR+0T+Y1aQgaq47yhWtMtlujxkzz7w0JQy+cdGMoZ46Sa2eFkzdyw7yOKaBLbE0mCwJs00uBgAG8nR/Ofjwd0uDkw== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=kLe0Khr6; dkim-atps=neutral; spf=pass (client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=david@kernel.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.org Authentication-Results: lists.ozlabs.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=kLe0Khr6; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=172.234.252.31; helo=sea.source.kernel.org; envelope-from=david@kernel.org; receiver=lists.ozlabs.org) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4dw5ZC262Sz2xpk for ; Tue, 20 Jan 2026 10:02:11 +1100 (AEDT) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id BAE984441F; Mon, 19 Jan 2026 23:02:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DCECC19424; Mon, 19 Jan 2026 23:02:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768863729; bh=9pFWzYgZbt+YY9kTe1GTcdn6HTneXxM/S/odovyu19w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kLe0Khr6DuCvasNoS6kxGtkTGY8Zw9brt5gCInhq8gLS+Ma4hsIx1369nWwQX1Tvf IB2XumFvNDI5jcl58bu1+Pu0ZrCudk7hz7m2H9Ax2cKzotO5pTZnVWOjCHvr53Owh9 wWCd3vv1ICESWBRIUrkH/QL8obmlOab1LlCb5uNL/xCEid0Q/hukDlzNIqcI0jUX7I MXYVPdAj/l45N6hoQMjhpukfeniE2KS3T4aRad/4Kfdv+ujJfbonv7OhpZdUpJlZdD v88zh6Y7ixYKz5JxWdDwhau0K/zyUQfHaZMYxvUzxiNBuApA2jLrvXlMoViRemVpHh F+IVwVmTXgxow== From: "David Hildenbrand (Red Hat)" To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Broadcom internal kernel review list , linux-doc@vger.kernel.org, virtualization@lists.linux.dev, "David Hildenbrand (Red Hat)" , Andrew Morton , Oscar Salvador , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Arnd Bergmann , Greg Kroah-Hartman , Jerrin Shaji George , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Zi Yan Subject: [PATCH v3 04/24] mm/balloon_compaction: improve comments for WARN_ON_ONCE(!b_dev_info) Date: Tue, 20 Jan 2026 00:01:12 +0100 Message-ID: <20260119230133.3551867-5-david@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260119230133.3551867-1-david@kernel.org> References: <20260119230133.3551867-1-david@kernel.org> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Let's clarify a bit by extending the comments. Signed-off-by: David Hildenbrand (Red Hat) --- mm/balloon_compaction.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c index 03c5dbabb1565..85eea88cea083 100644 --- a/mm/balloon_compaction.c +++ b/mm/balloon_compaction.c @@ -222,7 +222,11 @@ static void balloon_page_putback(struct page *page) struct balloon_dev_info *b_dev_info = balloon_page_device(page); unsigned long flags; - /* Isolated balloon pages cannot get deflated. */ + /* + * When we isolated the page, the page was still inflated in a balloon + * device. As isolated balloon pages cannot get deflated, we still have + * a balloon device here. + */ if (WARN_ON_ONCE(!b_dev_info)) return; @@ -241,7 +245,11 @@ static int balloon_page_migrate(struct page *newpage, struct page *page, VM_BUG_ON_PAGE(!PageLocked(page), page); VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); - /* Isolated balloon pages cannot get deflated. */ + /* + * When we isolated the page, the page was still inflated in a balloon + * device. As isolated balloon pages cannot get deflated, we still have + * a balloon device here. + */ if (WARN_ON_ONCE(!balloon)) return -EAGAIN; -- 2.52.0