>From 6589ddf69a1369e1ecb95f0af489d90b980e256e Mon Sep 17 00:00:00 2001 Message-Id: <6589ddf69a1369e1ecb95f0af489d90b980e256e.1469165371.git.luto@kernel.org> From: Andy Lutomirski Date: Thu, 21 Jul 2016 22:22:02 -0700 Subject: [PATCH] x86/mm: Fix populate_pgd() I make an obvious error in populate_pgd() -- it would fail to correctly populate the page tables when it allocated a new pud page. Fixes: 360cb4d15567 ("x86/mm/cpa: In populate_pgd(), don't set the PGD entry until it's populated") Reported-by: Valdis Kletnieks Signed-off-by: Andy Lutomirski --- arch/x86/mm/pageattr.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 26c93c6e04a0..5ee7d1c794a4 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -984,8 +984,8 @@ static int populate_pmd(struct cpa_data *cpa, return num_pages; } -static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd, - pgprot_t pgprot) +static int populate_pud(struct cpa_data *cpa, unsigned long start, + pud_t *pud_page, pgprot_t pgprot) { pud_t *pud; unsigned long end; @@ -1006,7 +1006,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd, cur_pages = (pre_end - start) >> PAGE_SHIFT; cur_pages = min_t(int, (int)cpa->numpages, cur_pages); - pud = pud_offset(pgd, start); + pud = pud_page + pud_index(start); /* * Need a PMD page? @@ -1027,7 +1027,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd, if (cpa->numpages == cur_pages) return cur_pages; - pud = pud_offset(pgd, start); + pud = pud_page + pud_index(start); pud_pgprot = pgprot_4k_2_large(pgprot); /* @@ -1047,7 +1047,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd, if (start < end) { int tmp; - pud = pud_offset(pgd, start); + pud = pud_page + pud_index(start); if (pud_none(*pud)) if (alloc_pmd_page(pud)) return -1; @@ -1069,7 +1069,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd, static int populate_pgd(struct cpa_data *cpa, unsigned long addr) { pgprot_t pgprot = __pgprot(_KERNPG_TABLE); - pud_t *pud = NULL; /* shut up gcc */ + pud_t *pud_page = NULL; /* shut up gcc */ pgd_t *pgd_entry; int ret; @@ -1079,25 +1079,27 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr) * Allocate a PUD page and hand it down for mapping. */ if (pgd_none(*pgd_entry)) { - pud = (pud_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK); - if (!pud) + pud_page = (pud_t *)get_zeroed_page(GFP_KERNEL | __GFP_NOTRACK); + if (!pud_page) return -1; } pgprot_val(pgprot) &= ~pgprot_val(cpa->mask_clr); pgprot_val(pgprot) |= pgprot_val(cpa->mask_set); - ret = populate_pud(cpa, addr, pgd_entry, pgprot); + ret = populate_pud(cpa, addr, + pud_page ?: (pud_t *)pgd_page_vaddr(*pgd_entry), + pgprot); if (ret < 0) { - if (pud) - free_page((unsigned long)pud); + if (pud_page) + free_page((unsigned long)pud_page); unmap_pud_range(pgd_entry, addr, addr + (cpa->numpages << PAGE_SHIFT)); return ret; } - if (pud) - set_pgd(pgd_entry, __pgd(__pa(pud) | _KERNPG_TABLE)); + if (pud_page) + set_pgd(pgd_entry, __pgd(__pa(pud_page) | _KERNPG_TABLE)); cpa->numpages = ret; return 0; -- 2.7.4