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 F09E9C433F5 for ; Thu, 2 Dec 2021 13:27:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6C18A6B0072; Thu, 2 Dec 2021 08:27:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6709C6B0073; Thu, 2 Dec 2021 08:27:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 55FA66B0074; Thu, 2 Dec 2021 08:27:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0148.hostedemail.com [216.40.44.148]) by kanga.kvack.org (Postfix) with ESMTP id 4426D6B0072 for ; Thu, 2 Dec 2021 08:27:28 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 7F4B78249980 for ; Thu, 2 Dec 2021 13:27:16 +0000 (UTC) X-FDA: 78872930472.19.5BB6C3E Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id D70FD7001A05 for ; Thu, 2 Dec 2021 13:27:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=N8VxYpGE+2Elyrz/sMTX7Mk/aRqmYqSy1LMlq3q5uls=; b=R1PZBTV6rorn2BRra37YZ8vc+j oR7AeNuq9scGaKUgNOxlHYZTbGzTYDWWv/RIRCYxJ5T8VUC83uIXH3yf3X4Mch79znEb2QEvPc3tZ R3lNK3b/bwElqKsnOX5uC3U+vVPrTo7URf6AJwSnSyKu8fb4WGnI1lnzt2YE99rnz1jRQIhUNv3o8 fLDhOJ3GX0oJ4Zf7flF8nTUoRB7b4vMG441ZX1gQjZYowcvb6hUknerhR1t/TkLxzWyMfUDTZam3q bdr0Sjcwu+mkqzL8a+L19h7d4i4HKIHgi0W47OvwjjXBojbXNuNg2q3vhJcNObac1KqWQ8HrbWsmn Alq+vHjg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1msm77-0046py-K8; Thu, 02 Dec 2021 13:27:05 +0000 Date: Thu, 2 Dec 2021 13:27:05 +0000 From: Matthew Wilcox To: Charan Teja Reddy Cc: hughd@google.com, akpm@linux-foundation.org, vbabka@suse.cz, rientjes@google.com, david@redhat.com, mhocko@suse.com, surenb@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Charan Teja Reddy Subject: Re: [PATCH v2] mm: shmem: implement POSIX_FADV_[WILL|DONT]NEED for shmem Message-ID: References: <1638442253-1591-1-git-send-email-quic_charante@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1638442253-1591-1-git-send-email-quic_charante@quicinc.com> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: D70FD7001A05 X-Stat-Signature: 8qjpi4c4i5bkixkwnobeypzxfcgc1y7y Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=R1PZBTV6; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-HE-Tag: 1638451633-81041 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000080, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Dec 02, 2021 at 04:20:53PM +0530, Charan Teja Reddy wrote: > +static int shmem_fadvise_willneed(struct address_space *mapping, > + pgoff_t start, pgoff_t long end) > +{ > + XA_STATE(xas, &mapping->i_pages, start); > + struct page *page; > + > + rcu_read_lock(); > + page = xas_find(&xas, end); > + rcu_read_unlock(); > + > + while (page) { > + if (xa_is_value(page)) { > + page = shmem_read_mapping_page(mapping, xas.xa_index); > + if (!IS_ERR(page)) > + put_page(page); > + } > + > + if (need_resched()) { > + xas_pause(&xas); > + cond_resched(); > + } > + > + rcu_read_lock(); > + page = xas_next_entry(&xas, end); > + rcu_read_unlock(); > + } > + > + return 0; > +} What part of the XArray documentation led you to believe that this is a safe thing to do? Because it needs to be rewritten immediately!