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

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

Signed-off-by: Peter 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: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2018-12-03 18:03:50 +01:00 committed by Ingo Molnar
parent 935f583982
commit 83b4e39146
1 changed files with 13 additions and 8 deletions
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21
arch/x86/mm/pageattr.c
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@ -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;
}
/*