> -----Original Message-----
> From: Vaishali Thakkar [mailto:vaishali.thak...@oracle.com]
> Sent: Wednesday, March 23, 2016 8:22 PM
> To: a...@linux-foundation.org
> Cc: linux...@kvack.org; linux-kernel@vger.kernel.org; Vaishali Thakkar; Hillf
> Danton; Michal Hocko; Yaowei Bai; Dominik Dingel;
Kirill
> A. Shutemov; Paul Gortmaker; Dave Hansen
> Subject: [PATCH v2 1/6] mm/hugetlb: Introduce hugetlb_bad_size
>
> 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 <vaishali.thak...@oracle.com>
> Reviewed-by: Mike Kravetz <mike.krav...@oracle.com>
> Reviewed-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
> Cc: Hillf Danton <hillf...@alibaba-inc.com>
> Cc: Michal Hocko <mho...@suse.com>
> Cc: Yaowei Bai <baiyao...@cmss.chinamobile.com>
> Cc: Dominik Dingel <din...@linux.vnet.ibm.com>
> Cc: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
> Cc: Paul Gortmaker <paul.gortma...@windriver.com>
> Cc: Dave Hansen <dave.han...@linux.intel.com>
> ---
Acked-by: Hillf Danton <hillf...@alibaba-inc.com>
> The patch is having 2 checkpatch.pl warnings. I have just followed
> the current code to maintain consistency.
> Changes since v1:
> - Nothing in this patch, just separated changes done in second
> patch
> ---
> 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..5ebdd869 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);
> + 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)
> mhp = &default_hstate_max_huge_pages;
> else
> mhp = &parsed_hstate->max_huge_pages;
> --
> 2.1.4
