From nobody Sat Apr 11 12:45:37 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6602FC19F2A for ; Thu, 11 Aug 2022 15:44:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236437AbiHKPoB (ORCPT ); Thu, 11 Aug 2022 11:44:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236481AbiHKPnl (ORCPT ); Thu, 11 Aug 2022 11:43:41 -0400 Received: from mail.sberdevices.ru (mail.sberdevices.ru [45.89.227.171]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D1AC9F196 for ; Thu, 11 Aug 2022 08:38:08 -0700 (PDT) Received: from s-lin-edge02.sberdevices.ru (localhost [127.0.0.1]) by mail.sberdevices.ru (Postfix) with ESMTP id 14A535FD05; Thu, 11 Aug 2022 18:38:06 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sberdevices.ru; s=mail; t=1660232286; bh=A3K4ViyKorIBmbrqaPTPKHLFa5vS3HsOnKdz/6fJLUw=; h=From:To:Subject:Date:Message-ID:MIME-Version:Content-Type; b=CjfUu6Mk1eOrgCOGEJXFiabeAfvs9yI04vID5EUtRBLVtn12/Tc1GhJgo+8hwgZNA S307IjqsKalvRqjSLYykiOcApED8RUj8XniHQb5/z5O3TBsyORSIi2e0NCqT76DKmF G2KJb8rXHRwnfIgF4rIdk9Az/kXMCTDNIwLUD2d1ro8sGK6w7/SXAl+nF+i1tB0+sn wf3xeTcmNDNWU1fcj6S35CWLQoje4NysqJsb/CYntr67eik5gOgn+V61nc5Gn2fKDT AYcPRkKa5PcbZrpL5/RzeK9VuDp8MZCd+d2DtPNZnzPOCfP2rv6+1LKG3RHza4w6KJ yp87fQkE6dMww== Received: from S-MS-EXCH01.sberdevices.ru (S-MS-EXCH01.sberdevices.ru [172.16.1.4]) by mail.sberdevices.ru (Postfix) with ESMTP; Thu, 11 Aug 2022 18:38:06 +0300 (MSK) From: Alexey Romanov To: , , , CC: , , , Alexey Romanov Subject: [PATCH v1 1/2] zsmalloc: zs_object_copy: add clarifying comment Date: Thu, 11 Aug 2022 18:37:54 +0300 Message-ID: <20220811153755.16102-2-avromanov@sberdevices.ru> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20220811153755.16102-1-avromanov@sberdevices.ru> References: <20220811153755.16102-1-avromanov@sberdevices.ru> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [172.16.1.6] X-ClientProxiedBy: S-MS-EXCH01.sberdevices.ru (172.16.1.4) To S-MS-EXCH01.sberdevices.ru (172.16.1.4) X-KSMG-Rule-ID: 4 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Status: not scanned, disabled by settings X-KSMG-AntiSpam-Interceptor-Info: not scanned X-KSMG-AntiPhishing: not scanned, disabled by settings X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 1.1.2.30, bases: 2022/08/11 13:20:00 #20096813 X-KSMG-AntiVirus-Status: Clean, skipped Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It's not obvious why kunmap_atomic(d_addr) call is needed. Signed-off-by: Alexey Romanov --- mm/zsmalloc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 5d5fc04385b8..5efa8c592193 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1564,6 +1564,12 @@ static void zs_object_copy(struct size_class *class,= unsigned long dst, d_off +=3D size; d_size -=3D size; =20 + /* Calling kunmap_atomic(d_addr) is necessary. kunmap_atomic() calls + * must occurs in reverse order of calls to kmap_atomic(). + * So, to call kunmap_atomic(s_addr) we should first call kunmap_atomic(= d_addr). + * For more details see: + * https://lore.kernel.org/linux-mm/5512421D.4000603@samsung.com/ + */ if (s_off >=3D PAGE_SIZE) { kunmap_atomic(d_addr); kunmap_atomic(s_addr); --=20 2.30.1