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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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3
arch/parisc/mm/init.c
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@@ -505,7 +505,9 @@ void show_mem(void)
for (j = node_start_pfn(i); j < node_end_pfn(i); j++) {
struct page *p;
unsigned long flags;
pgdat_resize_lock(NODE_DATA(i), &flags);
p = nid_page_nr(i, j) - node_start_pfn(i);
total++;
@@ -517,6 +519,7 @@ void show_mem(void)
free++;
else
shared += page_count(p) - 1;
pgdat_resize_unlock(NODE_DATA(i), &flags);
}
}
#endif