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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D6A5C433F5 for ; Fri, 24 Sep 2021 22:43:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D55AC610C7 for ; Fri, 24 Sep 2021 22:43:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D55AC610C7 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=kvack.org Received: by kanga.kvack.org (Postfix) id 79D376B0078; Fri, 24 Sep 2021 18:43:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 74C8A6B007B; Fri, 24 Sep 2021 18:43:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 63B076B007D; Fri, 24 Sep 2021 18:43:34 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 53EF36B0078 for ; Fri, 24 Sep 2021 18:43:34 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id F331E180374DC for ; Fri, 24 Sep 2021 22:43:33 +0000 (UTC) X-FDA: 78623945106.05.6AA12F2 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf18.hostedemail.com (Postfix) with ESMTP id B96584002085 for ; Fri, 24 Sep 2021 22:43:33 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id AF0CC61019; Fri, 24 Sep 2021 22:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1632523412; bh=E114ElZcTSr+5tsI5+ea0qeRXF7axUHZkgjp/Ds95ac=; h=Date:From:To:Subject:In-Reply-To:From; b=kP8Dhy7t1QyS6l9UW27bXAnPTiAgdkQxJ0+QDqHd+E823LJpfEa7CjhUDAoihZSSU jQd2uOOJL00p2SxNW0mceGXpCzVrbGXeSuOUzoxKLjTsj41k2ssqUCxAi9V2QMcmX5 vNHj3YYkdeXTPqFLTsMCHcVz56tuiSWHvz5w0d2A= Date: Fri, 24 Sep 2021 15:43:32 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, liuyuntao10@huawei.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, wuxu.wu@huawei.com Subject: [patch 05/16] mm/shmem.c: fix judgment error in shmem_is_huge() Message-ID: <20210924224332.489iilWzd%akpm@linux-foundation.org> In-Reply-To: <20210924154257.1dbf6699ab8d88c0460f924f@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B96584002085 X-Stat-Signature: 69heymbaghp59ttkfkqykwkay7u8wcej Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=kP8Dhy7t; dmarc=none; spf=pass (imf18.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1632523413-982396 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: Liu Yuntao Subject: mm/shmem.c: fix judgment error in shmem_is_huge() In the case of SHMEM_HUGE_WITHIN_SIZE, the page index is not rounded up correctly. When the page index points to the first page in a huge page, round_up() cannot bring it to the end of the huge page, but to the end of the previous one. An example: HPAGE_PMD_NR on my machine is 512(2 MB huge page size). After allcoating a 3000 KB buffer, I access it at location 2050 KB. In shmem_is_huge(), the corresponding index happens to be 512. After rounded up by HPAGE_PMD_NR, it will still be 512 which is smaller than i_size, and shmem_is_huge() will return true. As a result, my buffer takes an additional huge page, and that shouldn't happen when shmem_enabled is set to within_size. Link: https://lkml.kernel.org/r/20210909032007.18353-1-liuyuntao10@huawei.com Fixes: f3f0e1d2150b2b ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Liu Yuntao Acked-by: Kirill A. Shutemov Acked-by: Hugh Dickins Cc: wuxu.wu Signed-off-by: Andrew Morton --- mm/shmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/shmem.c~fix-judgment-error-in-shmem_is_huge +++ a/mm/shmem.c @@ -490,9 +490,9 @@ bool shmem_is_huge(struct vm_area_struct case SHMEM_HUGE_ALWAYS: return true; case SHMEM_HUGE_WITHIN_SIZE: - index = round_up(index, HPAGE_PMD_NR); + index = round_up(index + 1, HPAGE_PMD_NR); i_size = round_up(i_size_read(inode), PAGE_SIZE); - if (i_size >= HPAGE_PMD_SIZE && (i_size >> PAGE_SHIFT) >= index) + if (i_size >> PAGE_SHIFT >= index) return true; fallthrough; case SHMEM_HUGE_ADVISE: _