Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750796AbcCWEDF (ORCPT ); Wed, 23 Mar 2016 00:03:05 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:42832 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750699AbcCWEDC (ORCPT ); Wed, 23 Mar 2016 00:03:02 -0400 Subject: Re: [PATCH 1/2] mm/hugetlb: Introduce hugetlb_bad_size To: SeongJae Park References: <1458640843-13483-1-git-send-email-vaishali.thakkar@oracle.com> 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 From: Vaishali Thakkar Message-ID: <56F2154F.4090505@oracle.com> Date: Wed, 23 Mar 2016 09:32:23 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5192 Lines: 138 On Wednesday 23 March 2016 04:57 AM, SeongJae Park wrote: > 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. > As I said above, I just followed the pattern of the current code to maintain the consistency. Probably a separate change would be good for solving all those warnings. :) >> + 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? > I think above change is necessary for the cases like "hugepages=X" because in that case the X hugepages of the default size [like 2M for x86] should be allocated. >> 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 >> -- Vaishali