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x86, cpa: no need to check alias for __set_pages_p/__set_pages_np

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No alias checking needed for setting present/not-present mapping. Otherwise,
we may need to break large pages for 64-bit kernel text mappings (this adds to
complexity if we want to do this from atomic context especially, for ex:
with CONFIG_DEBUG_PAGEALLOC). Let's keep it simple!

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: arjan@linux.intel.com
Cc: venkatesh.pallipadi@intel.com
Cc: jeremy@goop.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Suresh Siddha 2008-09-23 14:00:40 -07:00 committed by Ingo Molnar
parent 0b8fdcbcd2
commit 55121b4369
1 changed files with 16 additions and 7 deletions
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23
arch/x86/mm/pageattr.c
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@ -1121,7 +1121,13 @@ static int __set_pages_p(struct page *page, int numpages)
.mask_clr = __pgprot(0),
.flags = 0};
return __change_page_attr_set_clr(&cpa, 1);
/*
* No alias checking needed for setting present flag. otherwise,
* we may need to break large pages for 64-bit kernel text
* mappings (this adds to complexity if we want to do this from
* atomic context especially). Let's keep it simple!
*/
return __change_page_attr_set_clr(&cpa, 0);
}
static int __set_pages_np(struct page *page, int numpages)
@ -1133,7 +1139,13 @@ static int __set_pages_np(struct page *page, int numpages)
.mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW),
.flags = 0};
return __change_page_attr_set_clr(&cpa, 1);
/*
* No alias checking needed for setting not present flag. otherwise,
* we may need to break large pages for 64-bit kernel text
* mappings (this adds to complexity if we want to do this from
* atomic context especially). Let's keep it simple!
*/
return __change_page_attr_set_clr(&cpa, 0);
}
void kernel_map_pages(struct page *page, int numpages, int enable)
@ -1153,11 +1165,8 @@ void kernel_map_pages(struct page *page, int numpages, int enable)
/*
* The return value is ignored as the calls cannot fail.
* Large pages are kept enabled at boot time, and are
* split up quickly with DEBUG_PAGEALLOC. If a splitup
* fails here (due to temporary memory shortage) no damage
* is done because we just keep the largepage intact up
* to the next attempt when it will likely be split up:
* Large pages for identity mappings are not used at boot time
* and hence no memory allocations during large page split.
*/
if (enable)
__set_pages_p(page, numpages);