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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E4EAC5B57D for ; Wed, 3 Jul 2019 00:53:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1338620B1F for ; Wed, 3 Jul 2019 00:53:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562115191; bh=paq3rBGRhLW2Qpm44+MevTEqQRAXrHYmPUYx69zxz/M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=mSG7iHQYF9TwQ9hwIX1m2SLRz4G135xcdhAjA+s4LtzB3laENlun91r/2UK7S3aaU ckoSIyrLV2pW0HqW9EQ9csWpSAZ4WzvCCziTlA8FztADCRW46LOWj8S+xwhi7sHAN2 Wk6dEhsi5JolWiW2eSnmVPhbau4xKeQlOZTpT8Ps= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727207AbfGCAxF (ORCPT ); Tue, 2 Jul 2019 20:53:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:47372 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727066AbfGCAxF (ORCPT ); Tue, 2 Jul 2019 20:53:05 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E41A218E0; Tue, 2 Jul 2019 22:24:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562106249; bh=paq3rBGRhLW2Qpm44+MevTEqQRAXrHYmPUYx69zxz/M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=W75jKD/rNzq2PuPQpltd8H0MgbE9WV7KUI0OFTUGJiv4fPwyzhUtfkvdxeVlqOkFL 4b4xWxBzPXNyswEVKmLNwRI3tbXoIQnWMp3m/zqn80P3dgemCD1FV6iQddz/Pfn4vq yEgltIRFEizLLcYCPK78BUk8j0MPX6sFGN8Y+qYk= Date: Tue, 2 Jul 2019 15:24:09 -0700 From: Andrew Morton To: Henry Burns Cc: Shakeel Butt , Vitaly Wool , Vitaly Vul , Mike Rapoport , Xidong Wang , Jonathan Adams , Linux MM , LKML Subject: Re: [PATCH v2] mm/z3fold.c: Lock z3fold page before __SetPageMovable() Message-Id: <20190702152409.21c6c3787d125d61fb47840a@linux-foundation.org> In-Reply-To: References: <20190702005122.41036-1-henryburns@google.com> <20190702141930.e31bf1c07a77514d976ef6e2@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2 Jul 2019 15:17:47 -0700 Henry Burns wrote: > > > > > + if (can_sleep) { > > > > > + lock_page(page); > > > > > + __SetPageMovable(page, pool->inode->i_mapping); > > > > > + unlock_page(page); > > > > > + } else { > > > > > + if (!WARN_ON(!trylock_page(page))) { > > > > > + __SetPageMovable(page, pool->inode->i_mapping); > > > > > + unlock_page(page); > > > > > + } else { > > > > > + pr_err("Newly allocated z3fold page is locked\n"); > > > > > + WARN_ON(1); The WARN_ON will have already warned in this case. But the whole idea of warning in this case may be undesirable. We KNOW that the warning will sometimes trigger (yes?). So what's the point in scaring users? Also, pr_err(...)+WARN_ON(1) can basically be replaced with WARN(1, ...)? > > > > > + } > > > > > + }