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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED 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 0675EC11F6B for ; Thu, 1 Jul 2021 01:49:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B23DB61241 for ; Thu, 1 Jul 2021 01:49:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B23DB61241 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 383A48D01FC; Wed, 30 Jun 2021 21:49:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 35A498D01D0; Wed, 30 Jun 2021 21:49:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 221ED8D01FC; Wed, 30 Jun 2021 21:49:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0096.hostedemail.com [216.40.44.96]) by kanga.kvack.org (Postfix) with ESMTP id EE85E8D01D0 for ; Wed, 30 Jun 2021 21:49:22 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C4EE5181AEF3F for ; Thu, 1 Jul 2021 01:49:22 +0000 (UTC) X-FDA: 78312336564.26.C530795 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf15.hostedemail.com (Postfix) with ESMTP id 7981ED000097 for ; Thu, 1 Jul 2021 01:49:22 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 2BEB561469; Thu, 1 Jul 2021 01:49:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1625104161; bh=5xrnHgGUjf4XtwpufsBBiTLZuJ2GgK4jx5DkhGxwBt0=; h=Date:From:To:Subject:In-Reply-To:From; b=n40a4q3AMSr7kNo5+1xB7i889mu5RHYyzNZpq6LWMtJV5tcvfOQN+mbObp/kWpij5 k8mDA/CvD01Cj3oD67M5NSe1xA6ZTYvd6vMCGl6j/kbFirWZwm8C94/FTBsyrR6IP8 k9YRfHKDJscsgjyhyV83FFijsetzlfgcLw5rgj7w= Date: Wed, 30 Jun 2021 18:49:20 -0700 From: Andrew Morton To: aarcange@redhat.com, akpm@linux-foundation.org, almasrymina@google.com, axelrasmussen@google.com, bgeffon@google.com, dgilbert@redhat.com, hughd@google.com, jglisse@redhat.com, joe@perches.com, kirill@shutemov.name, linux-mm@kvack.org, lokeshgidra@google.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, oupton@google.com, peterx@redhat.com, rppt@linux.vnet.ibm.com, sfr@canb.auug.org.au, shli@fb.com, shuah@kernel.org, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, wangqing@vivo.com Subject: [patch 041/192] userfaultfd/shmem: support minor fault registration for shmem Message-ID: <20210701014920.bfUNqkkPY%akpm@linux-foundation.org> In-Reply-To: <20210630184624.9ca1937310b0dd5ce66b30e7@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=n40a4q3A; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7981ED000097 X-Stat-Signature: sock6a993jrnsp5yu3epbh1c13p7s99u X-HE-Tag: 1625104162-403041 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: From: Axel Rasmussen Subject: userfaultfd/shmem: support minor fault registration for shmem This patch allows shmem-backed VMAs to be registered for minor faults. Minor faults are appropriately relayed to userspace in the fault path, for VMAs with the relevant flag. This commit doesn't hook up the UFFDIO_CONTINUE ioctl for shmem-backed minor faults, though, so userspace doesn't yet have a way to resolve such faults. Because of this, we also don't yet advertise this as a supported feature. That will be done in a separate commit when the feature is fully implemented. Link: https://lkml.kernel.org/r/20210503180737.2487560-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen Acked-by: Peter Xu Acked-by: Hugh Dickins Cc: Alexander Viro Cc: Andrea Arcangeli Cc: Brian Geffon Cc: "Dr . David Alan Gilbert" Cc: Jerome Glisse Cc: Joe Perches Cc: Kirill A. Shutemov Cc: Lokesh Gidra Cc: Mike Kravetz Cc: Mike Rapoport Cc: Mina Almasry Cc: Oliver Upton Cc: Shaohua Li Cc: Shuah Khan Cc: Stephen Rothwell Cc: Wang Qing Signed-off-by: Andrew Morton --- fs/userfaultfd.c | 3 +-- mm/memory.c | 8 +++++--- mm/shmem.c | 12 +++++++++++- 3 files changed, 17 insertions(+), 6 deletions(-) --- a/fs/userfaultfd.c~userfaultfd-shmem-support-minor-fault-registration-for-shmem +++ a/fs/userfaultfd.c @@ -1267,8 +1267,7 @@ static inline bool vma_can_userfault(str } if (vm_flags & VM_UFFD_MINOR) { - /* FIXME: Add minor fault interception for shmem. */ - if (!is_vm_hugetlb_page(vma)) + if (!(is_vm_hugetlb_page(vma) || vma_is_shmem(vma))) return false; } --- a/mm/memory.c~userfaultfd-shmem-support-minor-fault-registration-for-shmem +++ a/mm/memory.c @@ -4026,9 +4026,11 @@ static vm_fault_t do_read_fault(struct v * something). */ if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { - ret = do_fault_around(vmf); - if (ret) - return ret; + if (likely(!userfaultfd_minor(vmf->vma))) { + ret = do_fault_around(vmf); + if (ret) + return ret; + } } ret = __do_fault(vmf); --- a/mm/shmem.c~userfaultfd-shmem-support-minor-fault-registration-for-shmem +++ a/mm/shmem.c @@ -1797,7 +1797,7 @@ unlock: * vm. If we swap it in we mark it dirty since we also free the swap * entry since a page cannot live in both the swap and page cache. * - * vmf and fault_type are only supplied by shmem_fault: + * vma, vmf, and fault_type are only supplied by shmem_fault: * otherwise they are NULL. */ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, @@ -1832,6 +1832,16 @@ repeat: page = pagecache_get_page(mapping, index, FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0); + + if (page && vma && userfaultfd_minor(vma)) { + if (!xa_is_value(page)) { + unlock_page(page); + put_page(page); + } + *fault_type = handle_userfault(vmf, VM_UFFD_MINOR); + return 0; + } + if (xa_is_value(page)) { error = shmem_swapin_page(inode, index, &page, sgp, gfp, vma, fault_type); _