>
> The patch titled
> Subject: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned memory is bad
> has been added to the -mm tree. Its filename is
> hotplug-memory-adding-non-section-aligned-memory-is-bad.patch
>
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>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> See
http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
> out what to do about this
>
> The current -mm tree may be found at
http://userweb.kernel.org/~akpm/mmotm/
>
> ------------------------------------------------------
> Subject: Subject: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned memory is bad
> From: Jeremy Fitzhardinge <jeremy@goop.org>
>
> Adding non-section-aligned memory will cause bad results, because page
> structures are only built on section-aligned boundaries. Also, memory
> whose size isn't a multiple of the section size is silently ignored.
>
> This patch adds a couple of WARN_ONs to help confused programmers work
> out what's going wrong when they hotplug memory without being aware of
> these constraints.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: Dave Hansen <dave@linux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> include/linux/mmzone.h | 3 +++
> mm/memory_hotplug.c | 5 +++++
> 2 files changed, 8 insertions(+)
>
> diff -puN include/linux/mmzone.h~hotplug-memory-adding-non-section-aligned-memory-is-bad include/linux/mmzone.h
> --- a/include/linux/mmzone.h~hotplug-memory-adding-non-section-aligned-memory-is-bad
> +++ a/include/linux/mmzone.h
> @@ -829,6 +829,9 @@ static inline unsigned long early_pfn_to
> #define PAGES_PER_SECTION (1UL << PFN_SECTION_SHIFT)
> #define PAGE_SECTION_MASK (~(PAGES_PER_SECTION-1))
>
> +#define SECTION_SIZE (1UL << SECTION_SIZE_BITS)
> +#define SECTION_SIZE_MASK (SECTION_SIZE - 1)
> +
> #define SECTION_BLOCKFLAGS_BITS \
> ((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS)
>
> diff -puN mm/memory_hotplug.c~hotplug-memory-adding-non-section-aligned-memory-is-bad mm/memory_hotplug.c
> --- a/mm/memory_hotplug.c~hotplug-memory-adding-non-section-aligned-memory-is-bad
> +++ a/mm/memory_hotplug.c
> @@ -301,6 +301,11 @@ int add_memory_resource(int nid, struct
> u64 start = res->start;
> u64 size = res->end - res->start + 1;
>
> + /* Adding non-section-aligned memory will give unexpected
> + and unintuitive results. */
> + WARN_ON((start & SECTION_SIZE_MASK) != 0);
> + WARN_ON((size & SECTION_SIZE_MASK) != 0);
> +
> if (!node_online(nid)) {
> pgdat = hotadd_new_pgdat(nid, start);
> if (!pgdat)
> _
>
> Patches currently in -mm which might be from
jeremy@goop.org are
>
> origin.patch
> git-x86.patch
> sparsemem-vmemmap-does-not-need-section-bits.patch
> kbuild-create-a-way-to-create-preprocessor-constants-from-c-expressions.patch
> pageflags-use-an-enum-for-the-flags.patch
> pageflags-get-rid-of-flags_reserved.patch
> pageflags-introduce-macros-to-generate-page-flag-functions.patch
> pageflags-convert-to-the-use-of-new-macros.patch
> pageflags-use-proper-page-flag-functions-in-xen.patch
> pageflags-eliminate-pg_xxx-aliases.patch
> hotplug-memory-add-add_memory_resource.patch
> hotplug-memory-adding-non-section-aligned-memory-is-bad.patch
> sparsemem-reduce-i386-pae-section-size.patch
> paravirt_ops-dont-steal-memory-resources-in-paravirt_disable_iospace.patch
> xen-make-blkif_getgeo-static.patch
>
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