The patch titled
Subject: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned memory is bad
has been removed from the -mm tree. Its filename was
hotplug-memory-adding-non-section-aligned-memory-is-bad.patch
This patch was dropped because an updated version will be merged
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@xxxxxxxx>
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@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
Cc: Christoph Lameter <clameter@xxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxx 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-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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