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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,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 3EA43C433DB for ; Thu, 7 Jan 2021 20:05:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04A81233F6 for ; Thu, 7 Jan 2021 20:05:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727147AbhAGUFn (ORCPT ); Thu, 7 Jan 2021 15:05:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:43682 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725944AbhAGUFm (ORCPT ); Thu, 7 Jan 2021 15:05:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610049856; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TISzhw64TZ2TP4IkjeSd/YhcRqzAwfX+QzRYX4JpuNw=; b=HPl2+lt8xveM7UI9TC+9JPPRhyXtuenjyPxMWjVtzJnmfG091BnEpJ2rZQRB/Lw4cbTAW2 68Io0knOEoZcWGhQUw0OAbOXibRllIT1rp2twMtSyIBo2632pi9HQTApP7ja5ARHHSpIWB 5iJxc3XmbjscAIe7OGwZw5Plr1jTZrE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-150-SKRQLejOP_qK39OqgzE4Uw-1; Thu, 07 Jan 2021 15:04:13 -0500 X-MC-Unique: SKRQLejOP_qK39OqgzE4Uw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AB23A80362B; Thu, 7 Jan 2021 20:04:10 +0000 (UTC) Received: from mail (ovpn-112-222.rdu2.redhat.com [10.10.112.222]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 519B46062F; Thu, 7 Jan 2021 20:04:03 +0000 (UTC) From: Andrea Arcangeli To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yu Zhao , Andy Lutomirski , Peter Xu , Pavel Emelyanov , Mike Kravetz , Mike Rapoport , Minchan Kim , Will Deacon , Peter Zijlstra , Linus Torvalds , Hugh Dickins , "Kirill A. Shutemov" , Matthew Wilcox , Oleg Nesterov , Jann Horn , Kees Cook , John Hubbard , Leon Romanovsky , Jason Gunthorpe , Jan Kara , Kirill Tkhai Subject: [PATCH 1/2] mm: proc: Invalidate TLB after clearing soft-dirty page state Date: Thu, 7 Jan 2021 15:04:01 -0500 Message-Id: <20210107200402.31095-2-aarcange@redhat.com> In-Reply-To: <20210107200402.31095-1-aarcange@redhat.com> References: <20210107200402.31095-1-aarcange@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Will Deacon 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 avoiding the mmu_gather API altogether: managing both the 'tlb_flush_pending' flag on the 'mm_struct' and explicit TLB invalidation for the sort-dirty path, much like mprotect() does already. Fixes: 0758cd830494 ("asm-generic/tlb: avoid potential double flush") Signed-off-by: Will Deacon Signed-off-by: Andrea Arcangeli --- fs/proc/task_mmu.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index ee5a235b3056..a127262ba517 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1189,7 +1189,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, struct mm_struct *mm; struct vm_area_struct *vma; enum clear_refs_types type; - struct mmu_gather tlb; int itype; int rv; @@ -1234,7 +1233,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, count = -EINTR; goto out_mm; } - tlb_gather_mmu(&tlb, mm, 0, -1); if (type == CLEAR_REFS_SOFT_DIRTY) { for (vma = mm->mmap; vma; vma = vma->vm_next) { if (!(vma->vm_flags & VM_SOFTDIRTY)) @@ -1252,15 +1250,18 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, break; } + inc_tlb_flush_pending(mm); mmu_notifier_range_init(&range, MMU_NOTIFY_SOFT_DIRTY, 0, NULL, mm, 0, -1UL); mmu_notifier_invalidate_range_start(&range); } walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops, &cp); - if (type == CLEAR_REFS_SOFT_DIRTY) + if (type == CLEAR_REFS_SOFT_DIRTY) { mmu_notifier_invalidate_range_end(&range); - tlb_finish_mmu(&tlb, 0, -1); + flush_tlb_mm(mm); + dec_tlb_flush_pending(mm); + } mmap_read_unlock(mm); out_mm: mmput(mm);