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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81734C433EF for ; Wed, 27 Oct 2021 03:05:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 049E0610CA for ; Wed, 27 Oct 2021 03:05:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 049E0610CA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 6C59A80007; Tue, 26 Oct 2021 23:05:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 67415940007; Tue, 26 Oct 2021 23:05:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 53AFD80007; Tue, 26 Oct 2021 23:05:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0139.hostedemail.com [216.40.44.139]) by kanga.kvack.org (Postfix) with ESMTP id 43E76940007 for ; Tue, 26 Oct 2021 23:05:42 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id D5034182B2530 for ; Wed, 27 Oct 2021 03:05:41 +0000 (UTC) X-FDA: 78740727282.07.3ED2950 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf12.hostedemail.com (Postfix) with ESMTP id 690EE10003D9 for ; Wed, 27 Oct 2021 03:05:41 +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=2QEJl6ydeEpfVKPrusTfke/4wYUwA/hZSkA+vyln7I4=; b=tWHS4LISDxbKziMnxAcTz+Mcs+ SOQRHzJMYyj2jwxGsZL8mQS8UGJhSFqDucTtCx23L7GkfDKrQt3XJw7UyC4DP+jn381BlRnbI/Ojj 3xjGmUHs6jBwtinLLrdkUs8uOPzvwHcBqJZ745+eoJ2hyMJ2M18lXh8x/b4nOYfdBdlLJhTwlsM9U 28qKZnMC9XgIVzmW4X9vMMLoeoD3chIRIuNgiOmOFPbVamvi/Jocg1BFWuBf1SSKWqTkRnulsnShJ DWI2AmaSc+1f4SmiSuwz2LrSCaToOKGi34n6AWQEreGWZXYb0QyrxeBCLTXvLSBNZuIzo6b1w3a2f niCz7ykA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfZF5-00HLvL-C4; Wed, 27 Oct 2021 03:04:56 +0000 Date: Wed, 27 Oct 2021 04:04:43 +0100 From: Matthew Wilcox To: Pasha Tatashin Cc: LKML , linux-mm , linux-m68k@lists.linux-m68k.org, Anshuman Khandual , Andrew Morton , william.kucharski@oracle.com, Mike Kravetz , Vlastimil Babka , Geert Uytterhoeven , schmitzmic@gmail.com, Steven Rostedt , Ingo Molnar , Johannes Weiner , Roman Gushchin , Muchun Song , weixugc@google.com, Greg Thelen Subject: Re: [RFC 1/8] mm: add overflow and underflow checks for page->_refcount Message-ID: References: <20211026173822.502506-1-pasha.tatashin@soleen.com> <20211026173822.502506-2-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 690EE10003D9 X-Stat-Signature: emttihrojihch7w9wnkrbyschzq4pr4a Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=tWHS4LIS; spf=none (imf12.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: 1635303941-72868 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Oct 26, 2021 at 09:21:29PM -0400, Pasha Tatashin wrote: > I think we can do that by using: > atomic_fetch_*() and check for overflow/underflow after operation. I > will send the updated series soon. Please include performance measurements. You're adding code to some hot paths.