Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752819AbcCVX1m (ORCPT ); Tue, 22 Mar 2016 19:27:42 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:36313 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751924AbcCVX1j (ORCPT ); Tue, 22 Mar 2016 19:27:39 -0400 From: SeongJae Park X-Google-Original-From: SeongJae Park Date: Wed, 23 Mar 2016 08:27:32 +0900 (KST) To: Vaishali Thakkar cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mike Kravetz , Naoya Horiguchi , Hillf Danton , Michal Hocko , Yaowei Bai , Dominik Dingel , "Kirill A. Shutemov" , Paul Gortmaker , Dave Hansen Subject: Re: [PATCH 1/2] mm/hugetlb: Introduce hugetlb_bad_size In-Reply-To: <1458640843-13483-1-git-send-email-vaishali.thakkar@oracle.com> Message-ID: References: <1458640843-13483-1-git-send-email-vaishali.thakkar@oracle.com> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4572 Lines: 123 Hello Vaishali, The patch looks good to me. However, I have few trivial questions. On Tue, 22 Mar 2016, Vaishali Thakkar wrote: > When any unsupported hugepage size is specified, 'hugepagesz=' and > 'hugepages=' should be ignored during command line parsing until any > supported hugepage size is found. But currently incorrect number of > hugepages are allocated when unsupported size is specified as it fails > to ignore the 'hugepages=' command. > > Test case: > > Note that this is specific to x86 architecture. > > Boot the kernel with command line option 'hugepagesz=256M hugepages=X'. > After boot, dmesg output shows that X number of hugepages of the size 2M > is pre-allocated instead of 0. > > So, to handle such command line options, introduce new routine > hugetlb_bad_size. The routine hugetlb_bad_size sets the global variable > parsed_valid_hugepagesz. We are using parsed_valid_hugepagesz to save the > state when unsupported hugepagesize is found so that we can ignore the > 'hugepages=' parameters after that and then reset the variable when > supported hugepage size is found. > > The routine hugetlb_bad_size can be called while setting 'hugepagesz=' > parameter in an architecture specific code. > > Signed-off-by: Vaishali Thakkar > Cc: Mike Kravetz > Cc: Naoya Horiguchi > Cc: Hillf Danton > Cc: Michal Hocko > Cc: Yaowei Bai > Cc: Dominik Dingel > Cc: Kirill A. Shutemov > Cc: Paul Gortmaker > Cc: Dave Hansen > --- > The patch is having 2 checkpatch.pl warnings. I have just followed > the current code to maintain consistency. If we decide to silent > these warnings then may be we should silent those warnings as well. > I am fine with any option whichever works best for everyone else. > --- > include/linux/hugetlb.h | 1 + > mm/hugetlb.c | 14 +++++++++++++- > 2 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 7d953c2..e44c578 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -338,6 +338,7 @@ int huge_add_to_page_cache(struct page *page, struct address_space *mapping, > /* arch callback */ > int __init alloc_bootmem_huge_page(struct hstate *h); > > +void __init hugetlb_bad_size(void); > void __init hugetlb_add_hstate(unsigned order); > struct hstate *size_to_hstate(unsigned long size); > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 06058ea..44fae6a 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -51,6 +51,7 @@ __initdata LIST_HEAD(huge_boot_pages); > static struct hstate * __initdata parsed_hstate; > static unsigned long __initdata default_hstate_max_huge_pages; > static unsigned long __initdata default_hstate_size; > +static bool __initdata parsed_valid_hugepagesz = true; > > /* > * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages, > @@ -2659,6 +2660,11 @@ static int __init hugetlb_init(void) > subsys_initcall(hugetlb_init); > > /* Should be called on processing a hugepagesz=... option */ > +void __init hugetlb_bad_size(void) > +{ > + parsed_valid_hugepagesz = false; > +} > + > void __init hugetlb_add_hstate(unsigned int order) > { > struct hstate *h; > @@ -2691,11 +2697,17 @@ static int __init hugetlb_nrpages_setup(char *s) > unsigned long *mhp; > static unsigned long *last_mhp; > > + if (!parsed_valid_hugepagesz) { > + pr_warn("hugepages = %s preceded by " > + "an unsupported hugepagesz, ignoring\n", s); How about concatenating the format string? `CodingStyle` now suggests to _never_ break every user-visible strings. > + parsed_valid_hugepagesz = true; > + return 1; > + } > /* > * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet, > * so this hugepages= parameter goes to the "default hstate". > */ > - if (!hugetlb_max_hstate) > + else if (!hugetlb_max_hstate) Because the upper `if` statement will do `return`, above change looks not significantly necessary. Is this intended? > mhp = &default_hstate_max_huge_pages; > else > mhp = &parsed_hstate->max_huge_pages; > -- > 2.1.4 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org >