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[PATCH] memory hotplug locking: node_size_lock

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pgdat->node_size_lock is basically only neeeded in one place in the normal
code: show_mem(), which is the arch-specific sysrq-m printing function.

Strictly speaking, the architectures not doing memory hotplug do no need this
locking in show_mem().  However, they are all included for completeness.  This
should also make any future consolidation of all of the implementations a
little more straightforward.

This lock is also held in the sparsemem code during a memory removal, as
sections are invalidated.  This is the place there pfn_valid() is made false
for a memory area that's being removed.  The lock is only required when doing
pfn_valid() operations on memory which the user does not already have a
reference on the page, such as in show_mem().

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Dave Hansen
2005-10-29 18:16:52 -07:00
committed by Linus Torvalds
parent c6a57e19e4
commit 208d54e551
9 changed files with 76 additions and 2 deletions
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7
arch/ia64/mm/discontig.c
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@@ -555,9 +555,13 @@ void show_mem(void)
show_free_areas();
printk("Free swap: %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
for_each_pgdat(pgdat) {
unsigned long present = pgdat->node_present_pages;
unsigned long present;
unsigned long flags;
int shared = 0, cached = 0, reserved = 0;
printk("Node ID: %d\n", pgdat->node_id);
pgdat_resize_lock(pgdat, &flags);
present = pgdat->node_present_pages;
for(i = 0; i < pgdat->node_spanned_pages; i++) {
struct page *page;
if (pfn_valid(pgdat->node_start_pfn + i))
@@ -571,6 +575,7 @@ void show_mem(void)
else if (page_count(page))
shared += page_count(page)-1;
}
pgdat_resize_unlock(pgdat, &flags);
total_present += present;
total_reserved += reserved;
total_cached += cached;