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 D75DCC433EF for ; Tue, 19 Apr 2022 16:31:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 57CA38D0083; Tue, 19 Apr 2022 12:31:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5021F8D0047; Tue, 19 Apr 2022 12:31:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3569D8D0083; Tue, 19 Apr 2022 12:31:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id 235948D0047 for ; Tue, 19 Apr 2022 12:31:52 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id E8A20250B8 for ; Tue, 19 Apr 2022 16:31:51 +0000 (UTC) X-FDA: 79374170022.17.EEEC5A8 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf31.hostedemail.com (Postfix) with ESMTP id 4A02320012 for ; Tue, 19 Apr 2022 16:31:50 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id E07011F753; Tue, 19 Apr 2022 16:31:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1650385909; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FO3XX7Rny2nsJoT+gYq0ibjOzFl1Xd4EM1kydabFEzE=; b=kjokVUJ3xRC0ikC463fBM8xhon5NE74/yvmE8X96/o1PsvEjmSm80uds6zRrMGyGjszGvm rOy1yIYyESFXkRyVxxueBHQrQFCezHrP8mP0NmExj+b1M6/gfZIM5Sx/L/1vU9iqwEdxAq CkATQbHpsq0f2Op5GAJyEbE+MCe5CnU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1650385909; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FO3XX7Rny2nsJoT+gYq0ibjOzFl1Xd4EM1kydabFEzE=; b=T9zksfhxLXx1ImU1UANHvwz0/HZ5i5o86PA59TzsIBJeQPbjUuPRdFLYwkLrmTn4rBRLJg EXWdcvejuv6xGpBQ== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 88124132E7; Tue, 19 Apr 2022 16:31:49 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id wDeNIPXjXmL5VQAAMHmgww (envelope-from ); Tue, 19 Apr 2022 16:31:49 +0000 Message-ID: <3cc33611-a430-1ce4-bb30-7dc62a530cb8@suse.cz> Date: Tue, 19 Apr 2022 18:31:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH v3 14/16] mm: support GUP-triggered unsharing of anonymous pages Content-Language: en-US To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Liang Zhang , Pedro Gomes , Oded Gabbay , linux-mm@kvack.org References: <20220329160440.193848-1-david@redhat.com> <20220329160440.193848-15-david@redhat.com> <9005b167-db08-c967-463b-5e0e092cbb6c@suse.cz> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: bscqqjeurqhges6sdqb9xzbhdsswngbj X-Rspam-User: Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=kjokVUJ3; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=T9zksfhx; dmarc=none; spf=pass (imf31.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 4A02320012 X-HE-Tag: 1650385910-358472 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 4/19/22 18:29, David Hildenbrand wrote: >>> @@ -4515,8 +4550,11 @@ static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) >>> /* `inline' is required to avoid gcc 4.1.2 build error */ >>> static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) >>> { >>> + const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; >>> + >>> if (vma_is_anonymous(vmf->vma)) { >>> - if (userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd)) >>> + if (unlikely(unshare) && >> >> Is this condition flipped, should it be "likely(!unshare)"? As the similar >> code in do_wp_page() does. > > Good catch, this should affect uffd-wp on THP -- it wouldn't trigger as expected. Thanks a lot for finding that! Yay, glad I was right this time. >> >>> + userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd)) >>> return handle_userfault(vmf, VM_UFFD_WP); >>> return do_huge_pmd_wp_page(vmf); >>> } >>> @@ -4651,10 +4689,11 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) >>> update_mmu_tlb(vmf->vma, vmf->address, vmf->pte); >>> goto unlock; >>> } >>> - if (vmf->flags & FAULT_FLAG_WRITE) { >>> + if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) { >>> if (!pte_write(entry)) >>> return do_wp_page(vmf); >>> - entry = pte_mkdirty(entry); >>> + else if (likely(vmf->flags & FAULT_FLAG_WRITE)) >>> + entry = pte_mkdirty(entry); >>> } >>> entry = pte_mkyoung(entry); >>> if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry, >> > > > So the following on top, right? Looks good! > diff --git a/mm/memory.c b/mm/memory.c > index 8b3cb73f5e44..4584c7e87a70 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3137,7 +3137,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) > free_swap_cache(old_page); > put_page(old_page); > } > - return page_copied && !unshare ? VM_FAULT_WRITE : 0; > + return (page_copied && !unshare) ? VM_FAULT_WRITE : 0; > oom_free_new: > put_page(new_page); > oom: > @@ -4604,7 +4604,7 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) > const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; > > if (vma_is_anonymous(vmf->vma)) { > - if (unlikely(unshare) && > + if (likely(!unshare) && > userfaultfd_huge_pmd_wp(vmf->vma, vmf->orig_pmd)) > return handle_userfault(vmf, VM_UFFD_WP); > return do_huge_pmd_wp_page(vmf); > >