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Commit 55121b43 authored by Suresh Siddha's avatar Suresh Siddha Committed by Ingo Molnar
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x86, cpa: no need to check alias for __set_pages_p/__set_pages_np 



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: default avatarSuresh 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: default avatarIngo Molnar <mingo@elte.hu>
parent 0b8fdcbc

arch/x86/mm/pageattr.c

+16 −7
Original line number Diff line number Diff line
@@ -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);