Commit 9b5cf48b authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Ingo Molnar
Browse files

x86: revert "x86: CPA: avoid split of alias mappings" 

Revert:

  commit 8be8f54b
  Author: Thomas Gleixner <tglx@linutronix.de>
  Date:   Sat Feb 23 20:43:21 2008 +0100

      x86: CPA: avoid split of alias mappings

because it clearly mishandles the case when __change_page_attr(), called
from __change_page_attr_set_clr(), changes cpa->processed to 1 and
cpa_process_alias(cpa) is executed right after that.

This crashes my x86-64 test box early in the boot process
(ref. http://bugzilla.kernel.org/show_bug.cgi?id=10140#c4

).

Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 038f2f72

arch/x86/mm/pageattr.c

+10 −11
Original line number Diff line number Diff line
@@ -26,7 +26,6 @@ struct cpa_data { 
	pgprot_t	mask_set;

	pgprot_t	mask_clr;

	int		numpages;

	int		processed;

	int		flushtlb;

	unsigned long	pfn;

};
@@ -291,8 +290,8 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, 
	 */

	nextpage_addr = (address + psize) & pmask;

	numpages = (nextpage_addr - address) >> PAGE_SHIFT;

	if (numpages < cpa->processed)

		cpa->processed = numpages;

	if (numpages < cpa->numpages)

		cpa->numpages = numpages;



	/*

	 * We are safe now. Check whether the new pgprot is the same:
@@ -319,7 +318,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, 
	 */

	addr = address + PAGE_SIZE;

	pfn++;

	for (i = 1; i < cpa->processed; i++, addr += PAGE_SIZE, pfn++) {

	for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE, pfn++) {

		pgprot_t chk_prot = static_protections(new_prot, addr, pfn);



		if (pgprot_val(chk_prot) != pgprot_val(new_prot))
@@ -343,7 +342,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, 
	 * that we limited the number of possible pages already to

	 * the number of pages in the large page.

	 */

	if (address == (nextpage_addr - psize) && cpa->processed == numpages) {

	if (address == (nextpage_addr - psize) && cpa->numpages == numpages) {

		/*

		 * The address is aligned and the number of pages

		 * covers the full page.
@@ -573,7 +572,7 @@ repeat: 
			set_pte_atomic(kpte, new_pte);

			cpa->flushtlb = 1;

		}

		cpa->processed = 1;

		cpa->numpages = 1;

		return 0;

	}
@@ -584,7 +583,7 @@ repeat: 
	do_split = try_preserve_large_page(kpte, address, cpa);

	/*

	 * When the range fits into the existing large page,

	 * return. cp->processed and cpa->tlbflush have been updated in

	 * return. cp->numpages and cpa->tlbflush have been updated in

	 * try_large_page:

	 */

	if (do_split <= 0)
@@ -663,7 +662,7 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias) 
		 * Store the remaining nr of pages for the large page

		 * preservation check.

		 */

		cpa->numpages = cpa->processed = numpages;

		cpa->numpages = numpages;



		ret = __change_page_attr(cpa, checkalias);

		if (ret)
@@ -680,9 +679,9 @@ 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->processed > numpages);

		numpages -= cpa->processed;

		cpa->vaddr += cpa->processed * PAGE_SIZE;

		BUG_ON(cpa->numpages > numpages);

		numpages -= cpa->numpages;

		cpa->vaddr += cpa->numpages * PAGE_SIZE;

	}

	return 0;

}

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