linux-kernel - Re: [PATCH v1 3/8] kexec: export PG

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Message-ID: <20181121060458.GC7386@MiWiFi-R3L-srv>
Date:   Wed, 21 Nov 2018 14:04:58 +0800
From:   Baoquan He <bhe@...hat.com>
To:     David Hildenbrand <david@...hat.com>
Cc:     linux-mm@...ck.org, Michal Hocko <mhocko@...e.com>,
        Arnd Bergmann <arnd@...db.de>, linux-pm@...r.kernel.org,
        pv-drivers@...are.com, Borislav Petkov <bp@...en8.de>,
        linux-doc@...r.kernel.org, kexec-ml <kexec@...ts.infradead.org>,
        linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
        Omar Sandoval <osandov@...com>,
        Kazuhito Hagio <k-hagio@...jp.nec.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        xen-devel@...ts.xenproject.org, linux-fsdevel@...r.kernel.org,
        devel@...uxdriverproject.org, Dave Young <dyoung@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Lianbo Jiang <lijiang@...hat.com>
Subject: Re: [PATCH v1 3/8] kexec: export PG_offline to VMCOREINFO

On 11/19/18 at 11:16am, David Hildenbrand wrote:
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 933cb3e45b98..093c9f917ed0 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -464,6 +464,8 @@ static int __init crash_save_vmcoreinfo_init(void)
>  	VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
>  #ifdef CONFIG_HUGETLB_PAGE
>  	VMCOREINFO_NUMBER(HUGETLB_PAGE_DTOR);
> +#define PAGE_OFFLINE_MAPCOUNT_VALUE	(~PG_offline)
> +	VMCOREINFO_NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE);
>  #endif

This solution looks good to me. One small concern is why we don't
export PG_offline to vmcoreinfo directly, then define
PAGE_OFFLINE_MAPCOUNT_VALUE in makedumpfile. We have been exporting
kernel data/MACRO directly, why this one is exceptional.

Thanks
Baoquan