Re: [PATCH] mm: fix a regression with HIGHMEM introduced by changeset 7f1290f2f2a4d
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-11-15 19:24:57
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On Wed, 14 Nov 2012 22:52:03 +0800 Jiang Liu [off-list ref] wrote:
So how about totally reverting the changeset 7f1290f2f2a4d2c3f1b7ce8e87256e052ca23125 and I will post another version once I found a cleaner way?
We do need to get this regression fixed and I guess that a
straightforward revert is an acceptable way of doing that, for now.
I queued the below, with a plan to send it to Linus next week.
From: Andrew Morton <akpm@linux-foundation.org>
Subject: revert "mm: fix-up zone present pages"
Revert
commit 7f1290f2f2a4d2c3f1b7ce8e87256e052ca23125
Author: Jianguo Wu [off-list ref]
AuthorDate: Mon Oct 8 16:33:06 2012 -0700
Commit: Linus Torvalds [off-list ref]
CommitDate: Tue Oct 9 16:22:54 2012 +0900
mm: fix-up zone present pages
That patch tried to fix a issue when calculating zone->present_pages, but
it caused a regression on 32bit systems with HIGHMEM. With that
changeset, reset_zone_present_pages() resets all zone->present_pages to
zero, and fixup_zone_present_pages() is called to recalculate
zone->present_pages when the boot allocator frees core memory pages into
buddy allocator. Because highmem pages are not freed by bootmem
allocator, all highmem zones' present_pages becomes zero.
Various options for improving the situation are being discussed but for
now, let's return to the 3.6 code.
Cc: Jianguo Wu <redacted>
Cc: Jiang Liu <redacted>
Cc: Petr Tesarik <redacted>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Mel Gorman <redacted>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Minchan Kim <redacted>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
arch/ia64/mm/init.c | 1 -
include/linux/mm.h | 4 ----
mm/bootmem.c | 10 +---------
mm/memory_hotplug.c | 7 -------
mm/nobootmem.c | 3 ---
mm/page_alloc.c | 34 ----------------------------------
6 files changed, 1 insertion(+), 58 deletions(-)
diff -puN arch/ia64/mm/init.c~revert-1 arch/ia64/mm/init.c--- a/arch/ia64/mm/init.c~revert-1
+++ a/arch/ia64/mm/init.c@@ -637,7 +637,6 @@ mem_init (void) high_memory = __va(max_low_pfn * PAGE_SIZE); - reset_zone_present_pages(); for_each_online_pgdat(pgdat) if (pgdat->bdata->node_bootmem_map) totalram_pages += free_all_bootmem_node(pgdat);
diff -puN include/linux/mm.h~revert-1 include/linux/mm.h
--- a/include/linux/mm.h~revert-1
+++ a/include/linux/mm.h@@ -1684,9 +1684,5 @@ static inline unsigned int debug_guardpa static inline bool page_is_guard(struct page *page) { return false; } #endif /* CONFIG_DEBUG_PAGEALLOC */ -extern void reset_zone_present_pages(void); -extern void fixup_zone_present_pages(int nid, unsigned long start_pfn, - unsigned long end_pfn); - #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */
diff -puN mm/bootmem.c~revert-1 mm/bootmem.c
--- a/mm/bootmem.c~revert-1
+++ a/mm/bootmem.c@@ -198,8 +198,6 @@ static unsigned long __init free_all_boo int order = ilog2(BITS_PER_LONG); __free_pages_bootmem(pfn_to_page(start), order); - fixup_zone_present_pages(page_to_nid(pfn_to_page(start)), - start, start + BITS_PER_LONG); count += BITS_PER_LONG; start += BITS_PER_LONG; } else {
@@ -210,9 +208,6 @@ static unsigned long __init free_all_boo if (vec & 1) { page = pfn_to_page(start + off); __free_pages_bootmem(page, 0); - fixup_zone_present_pages( - page_to_nid(page), - start + off, start + off + 1); count++; } vec >>= 1;
@@ -226,11 +221,8 @@ static unsigned long __init free_all_boo pages = bdata->node_low_pfn - bdata->node_min_pfn; pages = bootmem_bootmap_pages(pages); count += pages; - while (pages--) { - fixup_zone_present_pages(page_to_nid(page), - page_to_pfn(page), page_to_pfn(page) + 1); + while (pages--) __free_pages_bootmem(page++, 0); - } bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
diff -puN mm/memory_hotplug.c~revert-1 mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~revert-1
+++ a/mm/memory_hotplug.c@@ -106,7 +106,6 @@ static void get_page_bootmem(unsigned lo void __ref put_page_bootmem(struct page *page) { unsigned long type; - struct zone *zone; type = (unsigned long) page->lru.next; BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
@@ -117,12 +116,6 @@ void __ref put_page_bootmem(struct page set_page_private(page, 0); INIT_LIST_HEAD(&page->lru); __free_pages_bootmem(page, 0); - - zone = page_zone(page); - zone_span_writelock(zone); - zone->present_pages++; - zone_span_writeunlock(zone); - totalram_pages++; } }
diff -puN mm/nobootmem.c~revert-1 mm/nobootmem.c
--- a/mm/nobootmem.c~revert-1
+++ a/mm/nobootmem.c@@ -116,8 +116,6 @@ static unsigned long __init __free_memor return 0; __free_pages_memory(start_pfn, end_pfn); - fixup_zone_present_pages(pfn_to_nid(start >> PAGE_SHIFT), - start_pfn, end_pfn); return end_pfn - start_pfn; }
@@ -128,7 +126,6 @@ unsigned long __init free_low_memory_cor phys_addr_t start, end, size; u64 i; - reset_zone_present_pages(); for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL) count += __free_memory_core(start, end);
diff -puN mm/page_alloc.c~revert-1 mm/page_alloc.c
--- a/mm/page_alloc.c~revert-1
+++ a/mm/page_alloc.c@@ -6098,37 +6098,3 @@ void dump_page(struct page *page) dump_page_flags(page->flags); mem_cgroup_print_bad_page(page); } - -/* reset zone->present_pages */ -void reset_zone_present_pages(void) -{ - struct zone *z; - int i, nid; - - for_each_node_state(nid, N_HIGH_MEMORY) { - for (i = 0; i < MAX_NR_ZONES; i++) { - z = NODE_DATA(nid)->node_zones + i; - z->present_pages = 0; - } - } -} - -/* calculate zone's present pages in buddy system */ -void fixup_zone_present_pages(int nid, unsigned long start_pfn, - unsigned long end_pfn) -{ - struct zone *z; - unsigned long zone_start_pfn, zone_end_pfn; - int i; - - for (i = 0; i < MAX_NR_ZONES; i++) { - z = NODE_DATA(nid)->node_zones + i; - zone_start_pfn = z->zone_start_pfn; - zone_end_pfn = zone_start_pfn + z->spanned_pages; - - /* if the two regions intersect */ - if (!(zone_start_pfn >= end_pfn || zone_end_pfn <= start_pfn)) - z->present_pages += min(end_pfn, zone_end_pfn) - - max(start_pfn, zone_start_pfn); - } -}
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