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Commit 83b4e391 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

x86/mm/cpa: Make cpa_data::numpages invariant 



Make sure __change_page_attr_set_clr() doesn't modify cpa->numpages.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom.StDenis@amd.com
Cc: dave.hansen@intel.com
Link: http://lkml.kernel.org/r/20181203171043.493000228@infradead.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 935f5839

arch/x86/mm/pageattr.c

+13 −8
Original line number Diff line number Diff line
@@ -1625,14 +1625,15 @@ static int cpa_process_alias(struct cpa_data *cpa) 
static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)

{

	unsigned long numpages = cpa->numpages;

	int ret;

	unsigned long rempages = numpages;

	int ret = 0;



	while (numpages) {

	while (rempages) {

		/*

		 * Store the remaining nr of pages for the large page

		 * preservation check.

		 */

		cpa->numpages = numpages;

		cpa->numpages = rempages;

		/* for array changes, we can't use large page */

		if (cpa->flags & (CPA_ARRAY | CPA_PAGES_ARRAY))

			cpa->numpages = 1;
@@ -1643,12 +1644,12 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias) 
		if (!debug_pagealloc_enabled())

			spin_unlock(&cpa_lock);

		if (ret)

			return ret;

			goto out;



		if (checkalias) {

			ret = cpa_process_alias(cpa);

			if (ret)

				return ret;

				goto out;

		}



		/*
@@ -1656,11 +1657,15 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias) 
		 * CPA operation. Either a large page has been

		 * preserved or a single page update happened.

		 */

		BUG_ON(cpa->numpages > numpages || !cpa->numpages);

		numpages -= cpa->numpages;

		BUG_ON(cpa->numpages > rempages || !cpa->numpages);

		rempages -= cpa->numpages;

		cpa->curpage += cpa->numpages;

	}

	return 0;



out:

	/* Restore the original numpages */

	cpa->numpages = numpages;

	return ret;

}



/*