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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADE37C433EF for ; Tue, 18 Jan 2022 11:35:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2330A6B0072; Tue, 18 Jan 2022 06:35:51 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1E2AD6B0073; Tue, 18 Jan 2022 06:35:51 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0D2186B0074; Tue, 18 Jan 2022 06:35:51 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0237.hostedemail.com [216.40.44.237]) by kanga.kvack.org (Postfix) with ESMTP id EE1396B0072 for ; Tue, 18 Jan 2022 06:35:50 -0500 (EST) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id AAE15181D2099 for ; Tue, 18 Jan 2022 11:35:50 +0000 (UTC) X-FDA: 79043203260.09.0453B3C Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by imf24.hostedemail.com (Postfix) with ESMTP id 06779180005 for ; Tue, 18 Jan 2022 11:35:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1642505750; x=1674041750; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=Cy0koQENvuH2stwxfYpHpozbkdaaMyCBsaJF92/LpXA=; b=mOSoKQ5IABEvNxgvcmqndVO+myO2DoB2N39LohkZoONVSAeUyukyECYS 9jEdpi7TOEfXfZFp7RV8bE7GJqZAavPoC2A4GueaWjup63vxJPe2rC8jc tUgGS6NwLVJtV2iXBzFKJeNSOrh4/VeYqeSeq4zgCW0ZHyHP94FVCIlay 4=; Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-01.qualcomm.com with ESMTP; 18 Jan 2022 03:35:48 -0800 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jan 2022 03:35:48 -0800 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.922.19; Tue, 18 Jan 2022 03:35:48 -0800 Received: from [10.216.58.242] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.922.19; Tue, 18 Jan 2022 03:35:44 -0800 Subject: Re: [PATCH v3 RESEND] mm: shmem: implement POSIX_FADV_[WILL|DONT]NEED for shmem To: Matthew Wilcox CC: Mark Hemment , , Andrew Morton , , , , , , , , Charan Teja Reddy References: <1641488717-13865-1-git-send-email-quic_charante@quicinc.com> <2c66ba2e-1c65-3bdd-b91e-eb8391ec6dbf@quicinc.com> <61212ffd-3505-04d7-5403-932a10d676e7@quicinc.com> From: Charan Teja Kalla Message-ID: Date: Tue, 18 Jan 2022 17:05:40 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-Rspamd-Queue-Id: 06779180005 X-Stat-Signature: u787husymbuhydicpu4e8szoxzjgtedy Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=quicinc.com header.s=qcdkim header.b=mOSoKQ5I; dmarc=pass (policy=none) header.from=quicinc.com; spf=pass (imf24.hostedemail.com: domain of quic_charante@quicinc.com designates 199.106.114.38 as permitted sender) smtp.mailfrom=quic_charante@quicinc.com X-Rspamd-Server: rspam03 X-HE-Tag: 1642505749-895102 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hello Matthew, On 1/12/2022 7:05 PM, Charan Teja Kalla wrote: >>>>> + rcu_read_lock(); >>>>> + xas_for_each(&xas, page, end) { >>>>> + if (!xa_is_value(page)) >>>>> + continue; >>>>> + xas_pause(&xas); >>>>> + rcu_read_unlock(); >>>>> + >>>>> + page = shmem_read_mapping_page(mapping, xas.xa_index); >>>>> + if (!IS_ERR(page)) >>>>> + put_page(page); >>>>> + >>>>> + rcu_read_lock(); >>>>> + if (need_resched()) { >>>>> + xas_pause(&xas); >>>>> + cond_resched_rcu(); >>>>> + } >>>>> + } >>>>> + rcu_read_unlock(); >>> Even the xarray documentation says that: If most entries found during a >>> walk require you to call xas_pause(), the xa_for_each() iterator may be >>> more appropriate. > Yes. This should obviously be an xa_for_each() loop. In one of your patch[1], where we used xarray iterator, though most of the entries found requires to call xas_pause() but still endup in using xas_for_each() rather than xa_for_each(). Then, Should this code be changed to use xa_for_each()? The documentation also says that "The xas_for_each() iterator will expand into more inline code than xa_for_each()." [1]https://patchwork.kernel.org/project/linux-mm/patch/20200819184850.24779-4-willy@infradead.org/