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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 318D0C5519F for ; Fri, 20 Nov 2020 15:00:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4785222272 for ; Fri, 20 Nov 2020 15:00:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="W5Y9nvrd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4785222272 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 545326B0036; Fri, 20 Nov 2020 10:00:38 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4F89A6B005C; Fri, 20 Nov 2020 10:00:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 40C136B005D; Fri, 20 Nov 2020 10:00:38 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id 084006B0036 for ; Fri, 20 Nov 2020 10:00:37 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 7645E8249980 for ; Fri, 20 Nov 2020 15:00:37 +0000 (UTC) X-FDA: 77505108114.16.board89_34112812734c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id 6F915100E548D for ; Fri, 20 Nov 2020 15:00:30 +0000 (UTC) X-HE-Tag: board89_34112812734c X-Filterd-Recvd-Size: 4081 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Fri, 20 Nov 2020 15:00:29 +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=NiuizQJIYv9MbTQDyL6kr/KprFoXkhdzvZvshBrCr/c=; b=W5Y9nvrdN7SJJgjDkR857bMCI5 WgHN1yn81J7n4R9+szMLSLmcnueBnCeriem/X9E77Fyo7lEVbPZ07lRDMfAlChRRgeBKGwqc5bfct LLnxaiKkI6zv7oOZ784WCJYfOCPqkHFdboEpkz0F+l5ghqvPvM57ZT4gA/SITHMH++QiXCnBuf4Kx UMAi8saLKQE1xeDOIIV7D80RNnvq2lFflYqB0JUT8HOfOqyw6ddbLCzoAty4fhBrUpLAF7MqlxU2u 5WjZqhuqGlfe9gznf7/7Qr7PzDsWnu/wbk/Ma44+B95C5XvosCm2SHJnXd4hqshXaEz0rfjxjc6ei OG5ThHbg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kg7tg-00005F-Dg; Fri, 20 Nov 2020 15:00:24 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id CB369304D28; Fri, 20 Nov 2020 16:00:23 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A770C20244762; Fri, 20 Nov 2020 16:00:23 +0100 (CET) Date: Fri, 20 Nov 2020 16:00:23 +0100 From: Peter Zijlstra To: Will Deacon Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Catalin Marinas , Yu Zhao , Minchan Kim , Linus Torvalds , Anshuman Khandual , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 4/6] mm: proc: Invalidate TLB after clearing soft-dirty page state Message-ID: <20201120150023.GH3040@hirez.programming.kicks-ass.net> References: <20201120143557.6715-1-will@kernel.org> <20201120143557.6715-5-will@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201120143557.6715-5-will@kernel.org> 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 Fri, Nov 20, 2020 at 02:35:55PM +0000, Will Deacon wrote: > Since commit 0758cd830494 ("asm-generic/tlb: avoid potential double flush"), > TLB invalidation is elided in tlb_finish_mmu() if no entries were batched > via the tlb_remove_*() functions. Consequently, the page-table modifications > performed by clear_refs_write() in response to a write to > /proc//clear_refs do not perform TLB invalidation. Although this is > fine when simply aging the ptes, in the case of clearing the "soft-dirty" > state we can end up with entries where pte_write() is false, yet a > writable mapping remains in the TLB. > > Fix this by calling tlb_remove_tlb_entry() for each entry being > write-protected when cleating soft-dirty. > > @@ -1053,6 +1054,7 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma, > ptent = pte_wrprotect(old_pte); > ptent = pte_clear_soft_dirty(ptent); > ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent); > + tlb_remove_tlb_entry(tlb, pte, addr); > } else if (is_swap_pte(ptent)) { > ptent = pte_swp_clear_soft_dirty(ptent); > set_pte_at(vma->vm_mm, addr, pte, ptent); Oh! Yesterday when you had me look at this code; I figured the sane thing to do was to make it look more like mprotect(). Why did you chose to make it work with mmu_gather instead? I'll grant you that it's probably the smaller patch, but I still think it's weird to use mmu_gather here. Also, is tlb_remote_tlb_entry() actually correct? If you look at __tlb_remove_tlb_entry() you'll find that Power-Hash-32 will clear the entry, which might not be what we want here, we want to update the entrty.