Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752140AbcDUHF6 (ORCPT ); Thu, 21 Apr 2016 03:05:58 -0400 Received: from mga04.intel.com ([192.55.52.120]:46208 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbcDUHF4 (ORCPT ); Thu, 21 Apr 2016 03:05:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,512,1455004800"; d="scan'208";a="689756651" Date: Thu, 21 Apr 2016 03:06:25 -0400 From: Matthew Wilcox To: Toshi Kani Cc: Jan Kara , Andrew Morton , dan.j.williams@intel.com, viro@zeniv.linux.org.uk, ross.zwisler@linux.intel.com, kirill.shutemov@linux.intel.com, david@fromorbit.com, tytso@mit.edu, adilger.kernel@dilger.ca, linux-nvdimm@ml01.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/2] Align mmap address for DAX pmd mappings Message-ID: <20160421070625.GB29068@linux.intel.com> References: <1460652511-19636-1-git-send-email-toshi.kani@hpe.com> <20160415220531.c7b55adb5b26eb749fae3186@linux-foundation.org> <20160418202610.GA17889@quack2.suse.cz> <20160419182347.GA29068@linux.intel.com> <571844A1.5080703@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <571844A1.5080703@hpe.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1746 Lines: 45 On Wed, Apr 20, 2016 at 11:10:25PM -0400, Toshi Kani wrote: > How about moving the function (as is) to mm/huge_memory.c, rename it to > get_hugepage_unmapped_area(), which is defined to NULL in huge_mm.h > when TRANSPARENT_HUGEPAGE is unset? Great idea. Perhaps it should look something like this? unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { loff_t off, off_end, off_pmd; unsigned long len_pmd, addr_pmd; if (addr) goto out; if (IS_DAX(filp->f_mapping->host) && !IS_ENABLED(CONFIG_FS_DAX_PMD)) goto out; /* Kirill, please fill in the right condition here for THP pagecache */ off = (loff_t)pgoff << PAGE_SHIFT; off_end = off + len; off_pmd = round_up(off, PMD_SIZE); /* pmd-aligned start offset */ if ((off_end <= off_pmd) || ((off_end - off_pmd) < PMD_SIZE)) goto out; len_pmd = len + PMD_SIZE; if ((off + len_pmd) < off) goto out; addr_pmd = current->mm->get_unmapped_area(filp, NULL, len_pmd, pgoff, flags); if (!IS_ERR_VALUE(addr_pmd)) { addr_pmd += (off - addr_pmd) & (PMD_SIZE - 1); return addr_pmd; } out: return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags); } - I deleted the check for filp == NULL. It can't be NULL ... this is a file_operation ;-) - Why is len_pmd len + PMD_SIZE instead of round_up(len, PMD_SIZE)? - I'm still in two minds about passing 'addr' to the first call to get_unmapped_area() instead of NULL.