Commit-ID: 83b4e39146aa70913580966e0f2b78b7c3492760 Gitweb: https://git.kernel.org/tip/83b4e39146aa70913580966e0f2b78b7c3492760 Author: Peter Zijlstra <[email protected]> AuthorDate: Mon, 3 Dec 2018 18:03:50 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 17 Dec 2018 18:54:27 +0100
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) <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/mm/pageattr.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 351874259a71..12b69263e501 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -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; } /*
