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=-16.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 7257DC433E0 for ; Thu, 4 Feb 2021 18:34:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EF4F964D9A for ; Thu, 4 Feb 2021 18:34:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF4F964D9A Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 80B616B0070; Thu, 4 Feb 2021 13:34:53 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 7192A6B0071; Thu, 4 Feb 2021 13:34:53 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 58EA26B0072; Thu, 4 Feb 2021 13:34:53 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0224.hostedemail.com [216.40.44.224]) by kanga.kvack.org (Postfix) with ESMTP id 36EBE6B0070 for ; Thu, 4 Feb 2021 13:34:53 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 0008D1EF1 for ; Thu, 4 Feb 2021 18:34:52 +0000 (UTC) X-FDA: 77781436866.28.slip05_050ab6e275de Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id D0D336C3A for ; Thu, 4 Feb 2021 18:34:52 +0000 (UTC) X-HE-Tag: slip05_050ab6e275de X-Filterd-Recvd-Size: 7569 Received: from mail-qk1-f201.google.com (mail-qk1-f201.google.com [209.85.222.201]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Thu, 4 Feb 2021 18:34:52 +0000 (UTC) Received: by mail-qk1-f201.google.com with SMTP id s4so3448441qkj.18 for ; Thu, 04 Feb 2021 10:34:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=BOdWGt2YrrFhUAh6Oya9odQ31xPXJajGw7XfNah1Ei0=; b=NBHdLCMVmjlgN5mUcDN7btxS+7ZLWcclBrRA56QJlXrMR8QRMxe4LKcc+rDaJR88Tg 81ZpUhmRyV+2iRs9b9i6X1F53gwpkWEkrPHiso9lwqtE01nZ0LC76zIowyeGwRQger9n MvN1CUkSc5RzCH3+1uJPnTf4lcAKThO0g7tGROkLDYgTOlEt+CYUjMazGvYBxhzJ26is 2gH5HlvO0XbpfhMs2p9bBdRgOCjFHHwlv8y9M7F5y30awvPM3pYsdA3nlMCVnO+SfpbC VJuVKmjkYK4vCc8vvFkmNhpnzIoB+2Lu2ef0b8fXz1jWw9ZJYS+CaSQD16ThR+WRoF/o 1JOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=BOdWGt2YrrFhUAh6Oya9odQ31xPXJajGw7XfNah1Ei0=; b=Hd5Q83BTGJkeKKst2QRxF66Rk3+5M5NFQIVYHLZ6HEANOVrobKQAWqjZ84GLEjvL4O tkie/1JOQ7w9xEPdQDCfZgdCSklxQehijGCnKLURIyYmV97ziCwbq+Ro+6A55aFzAzBs pDG0H1kCIIA2tt38zg6COFL+1pqLDBZk2vkz27h+lyxc32qrxIJyHYhYhraluOiKoYCL tM8vefBIWEre/r6GnnVfUYIPLcYpA+PB35ZZdzSXWM+Axz0i4KnKEDlIJME9/LXOyKoG kD4/CHVoFPy8QkCwnKfLEpFh7cOSOf+dscgnme3H5DmfmkMV1w3JO7xp+EHsbRr6mxq2 tZsA== X-Gm-Message-State: AOAM533MvDeuCHOqt2bgfCFayr8E71KqlxO0qbRhedeWR/ifBod9bsIi yT+HrSJLTkh84SPW6AloGP0rCuNZMVfUkaDcfVLR X-Google-Smtp-Source: ABdhPJyPb3Mlg/0ElAXzwxLs8sVTCzLB5QqJgGLurcVZpTtQkepWRndQWdvko4eXoVcaKAI92jkYW/tc6Gcw4S4Evpba X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:b001:12c1:dc19:2089]) (user=axelrasmussen job=sendgmr) by 2002:a05:6214:2ee:: with SMTP id h14mr785467qvu.34.1612463691582; Thu, 04 Feb 2021 10:34:51 -0800 (PST) Date: Thu, 4 Feb 2021 10:34:27 -0800 In-Reply-To: <20210204183433.1431202-1-axelrasmussen@google.com> Message-Id: <20210204183433.1431202-5-axelrasmussen@google.com> Mime-Version: 1.0 References: <20210204183433.1431202-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.30.0.365.g02bc693789-goog Subject: [PATCH v4 04/10] hugetlb/userfaultfd: Unshare all pmds for hugetlbfs when register wp From: Axel Rasmussen To: Alexander Viro , Alexey Dobriyan , Andrea Arcangeli , Andrew Morton , Anshuman Khandual , Catalin Marinas , Chinwen Chang , Huang Ying , Ingo Molnar , Jann Horn , Jerome Glisse , Lokesh Gidra , "Matthew Wilcox (Oracle)" , Michael Ellerman , "=?UTF-8?q?Michal=20Koutn=C3=BD?=" , Michel Lespinasse , Mike Kravetz , Mike Rapoport , Nicholas Piggin , Peter Xu , Shaohua Li , Shawn Anastasio , Steven Rostedt , Steven Price , Vlastimil Babka Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Adam Ruprecht , Axel Rasmussen , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Mina Almasry , Oliver Upton Content-Type: text/plain; charset="UTF-8" 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: Peter Xu Huge pmd sharing for hugetlbfs is racy with userfaultfd-wp because userfaultfd-wp is always based on pgtable entries, so they cannot be shared. Walk the hugetlb range and unshare all such mappings if there is, right before UFFDIO_REGISTER will succeed and return to userspace. This will pair with want_pmd_share() in hugetlb code so that huge pmd sharing is completely disabled for userfaultfd-wp registered range. Signed-off-by: Peter Xu Signed-off-by: Axel Rasmussen --- fs/userfaultfd.c | 48 ++++++++++++++++++++++++++++++++++++ include/linux/mmu_notifier.h | 1 + 2 files changed, 49 insertions(+) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 894cc28142e7..a0f66e12026b 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -1190,6 +1191,50 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf, } } +/* + * This function will unconditionally remove all the shared pmd pgtable entries + * within the specific vma for a hugetlbfs memory range. + */ +static void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) +{ +#ifdef CONFIG_HUGETLB_PAGE + struct hstate *h = hstate_vma(vma); + unsigned long sz = huge_page_size(h); + struct mm_struct *mm = vma->vm_mm; + struct mmu_notifier_range range; + unsigned long address; + spinlock_t *ptl; + pte_t *ptep; + + if (!(vma->vm_flags & VM_MAYSHARE)) + return; + + /* + * No need to call adjust_range_if_pmd_sharing_possible(), because + * we're going to operate on the whole vma + */ + mmu_notifier_range_init(&range, MMU_NOTIFY_HUGETLB_UNSHARE, + 0, vma, mm, vma->vm_start, vma->vm_end); + mmu_notifier_invalidate_range_start(&range); + i_mmap_lock_write(vma->vm_file->f_mapping); + for (address = vma->vm_start; address < vma->vm_end; address += sz) { + ptep = huge_pte_offset(mm, address, sz); + if (!ptep) + continue; + ptl = huge_pte_lock(h, mm, ptep); + huge_pmd_unshare(mm, vma, &address, ptep); + spin_unlock(ptl); + } + flush_hugetlb_tlb_range(vma, vma->vm_start, vma->vm_end); + i_mmap_unlock_write(vma->vm_file->f_mapping); + /* + * No need to call mmu_notifier_invalidate_range(), see + * Documentation/vm/mmu_notifier.rst. + */ + mmu_notifier_invalidate_range_end(&range); +#endif +} + static void __wake_userfault(struct userfaultfd_ctx *ctx, struct userfaultfd_wake_range *range) { @@ -1448,6 +1493,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx.ctx = ctx; + if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma)) + hugetlb_unshare_all_pmds(vma); + skip: prev = vma; start = vma->vm_end; diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h index b8200782dede..ff50c8528113 100644 --- a/include/linux/mmu_notifier.h +++ b/include/linux/mmu_notifier.h @@ -51,6 +51,7 @@ enum mmu_notifier_event { MMU_NOTIFY_SOFT_DIRTY, MMU_NOTIFY_RELEASE, MMU_NOTIFY_MIGRATE, + MMU_NOTIFY_HUGETLB_UNSHARE, }; #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0) -- 2.30.0.365.g02bc693789-goog