From patchwork Wed Jun 10 20:13:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11598753 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 15F0392A for ; Wed, 10 Jun 2020 20:17:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3A4C207F9 for ; Wed, 10 Jun 2020 20:17:27 +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="Ib0/cbiZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730923AbgFJURB (ORCPT ); Wed, 10 Jun 2020 16:17:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730541AbgFJUNt (ORCPT ); Wed, 10 Jun 2020 16:13:49 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2C423C08C5D1; Wed, 10 Jun 2020 13:13:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=WueiR9ClBR+SuUmlwhBVixkLUapU9LiFVjs2FwKptFw=; b=Ib0/cbiZsMjrh5GZh4ZA8ZsdY2 klpGZJeArXDdQfA2xiQwLfZNtsV95uw+Q/RHNtGh8hpAOnotLkrSmMge24xAWMgPIZL9d6YQhdPIF P05camGYRlTJ1tZNEhJ4tv4nbwD86PMeP30wQ5SAxEZrgJSK68d9usY7lJFV1jiUEYpMen39soRQ4 yR7pcyiXFKgjgoumY2NiTcWzA/WgduKS2tg0ud4bV5A3+m9xmSoC66ciYwGftMtfGfx35qtwXGOSN 69rSoh0QIvooYftJKD2LAW91mhgPhd9WJGlRvA8pfxm/loFcLgvSh23dHahH1GVXhnmmrSZJHqY6C nPY9qiUA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jj76Z-0003Up-Vj; Wed, 10 Jun 2020 20:13:47 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 19/51] mm: Zero the head page, not the tail page Date: Wed, 10 Jun 2020 13:13:13 -0700 Message-Id: <20200610201345.13273-20-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200610201345.13273-1-willy@infradead.org> References: <20200610201345.13273-1-willy@infradead.org> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: "Matthew Wilcox (Oracle)" Pass the head page to zero_user_segment(), not the tail page, and adjust the byte offsets appropriately. Signed-off-by: Matthew Wilcox (Oracle) --- mm/shmem.c | 7 +++++++ mm/truncate.c | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index a05d129a45e9..55405d811cfd 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -898,11 +898,18 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, struct page *page = NULL; shmem_getpage(inode, start - 1, &page, SGP_READ); if (page) { + struct page *head = thp_head(page); unsigned int top = PAGE_SIZE; if (start > end) { top = partial_end; partial_end = 0; } + if (head != page) { + unsigned int diff = start - 1 - head->index; + partial_start += diff << PAGE_SHIFT; + top += diff << PAGE_SHIFT; + page = head; + } zero_user_segment(page, partial_start, top); set_page_dirty(page); unlock_page(page); diff --git a/mm/truncate.c b/mm/truncate.c index dd9ebc1da356..152974888124 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -374,12 +374,19 @@ void truncate_inode_pages_range(struct address_space *mapping, if (partial_start) { struct page *page = find_lock_page(mapping, start - 1); if (page) { + struct page *head = thp_head(page); unsigned int top = PAGE_SIZE; if (start > end) { /* Truncation within a single page */ top = partial_end; partial_end = 0; } + if (head != page) { + unsigned int diff = start - 1 - head->index; + partial_start += diff << PAGE_SHIFT; + top += diff << PAGE_SHIFT; + page = head; + } wait_on_page_writeback(page); zero_user_segment(page, partial_start, top); cleancache_invalidate_page(mapping, page);