From c0eb315ad9719e41ce44708455cc69df7ac9f3f8 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Thu, 29 Apr 2021 22:58:13 -0700 Subject: [PATCH] mm/vmalloc: fix HUGE_VMAP regression by enabling huge pages in vmalloc_to_page vmalloc_to_page returns NULL for addresses mapped by larger pages[*]. Whether or not a vmap is huge depends on the architecture details, alignments, boot options, etc., which the caller can not be expected to know. Therefore HUGE_VMAP is a regression for vmalloc_to_page. This change teaches vmalloc_to_page about larger pages, and returns the struct page that corresponds to the offset within the large page. This makes the API agnostic to mapping implementation details. [*] As explained by commit 029c54b095995 ("mm/vmalloc.c: huge-vmap: fail gracefully on unexpected huge vmap mappings") [npiggin@gmail.com: sparc32: add stub pud_page define for walking huge vmalloc page tables] Link: https://lkml.kernel.org/r/20210324232825.1157363-1-npiggin@gmail.com Link: https://lkml.kernel.org/r/20210317062402.533919-3-npiggin@gmail.com Signed-off-by: Nicholas Piggin Reviewed-by: Miaohe Lin Reviewed-by: Christoph Hellwig Cc: Borislav Petkov Cc: Catalin Marinas Cc: Ding Tianhong Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Michael Ellerman Cc: Russell King Cc: Thomas Gleixner Cc: Uladzislau Rezki (Sony) Cc: Will Deacon Cc: Stephen Rothwell Cc: David S. Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/sparc/include/asm/pgtable_32.h | 3 +++ mm/vmalloc.c | 41 +++++++++++++++++++++++-------------- 2 files changed, 29 insertions(+), 15 deletions(-) diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h index 632cdb9..a5cf79c 100644 --- a/arch/sparc/include/asm/pgtable_32.h +++ b/arch/sparc/include/asm/pgtable_32.h @@ -321,6 +321,9 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) pgprot_val(newprot)); } +/* only used by the huge vmap code, should never be called */ +#define pud_page(pud) NULL + struct seq_file; void mmu_info(struct seq_file *m); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 8c20670..ee865b6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -34,7 +34,7 @@ #include #include #include - +#include #include #include #include @@ -343,7 +343,9 @@ int is_vmalloc_or_module_addr(const void *x) } /* - * Walk a vmap address to the struct page it maps. + * Walk a vmap address to the struct page it maps. Huge vmap mappings will + * return the tail page that corresponds to the base page address, which + * matches small vmap mappings. */ struct page *vmalloc_to_page(const void *vmalloc_addr) { @@ -363,25 +365,33 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) if (pgd_none(*pgd)) return NULL; + if (WARN_ON_ONCE(pgd_leaf(*pgd))) + return NULL; /* XXX: no allowance for huge pgd */ + if (WARN_ON_ONCE(pgd_bad(*pgd))) + return NULL; + p4d = p4d_offset(pgd, addr); if (p4d_none(*p4d)) return NULL; - pud = pud_offset(p4d, addr); + if (p4d_leaf(*p4d)) + return p4d_page(*p4d) + ((addr & ~P4D_MASK) >> PAGE_SHIFT); + if (WARN_ON_ONCE(p4d_bad(*p4d))) + return NULL; - /* - * Don't dereference bad PUD or PMD (below) entries. This will also - * identify huge mappings, which we may encounter on architectures - * that define CONFIG_HAVE_ARCH_HUGE_VMAP=y. Such regions will be - * identified as vmalloc addresses by is_vmalloc_addr(), but are - * not [unambiguously] associated with a struct page, so there is - * no correct value to return for them. - */ - WARN_ON_ONCE(pud_bad(*pud)); - if (pud_none(*pud) || pud_bad(*pud)) + pud = pud_offset(p4d, addr); + if (pud_none(*pud)) + return NULL; + if (pud_leaf(*pud)) + return pud_page(*pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); + if (WARN_ON_ONCE(pud_bad(*pud))) return NULL; + pmd = pmd_offset(pud, addr); - WARN_ON_ONCE(pmd_bad(*pmd)); - if (pmd_none(*pmd) || pmd_bad(*pmd)) + if (pmd_none(*pmd)) + return NULL; + if (pmd_leaf(*pmd)) + return pmd_page(*pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); + if (WARN_ON_ONCE(pmd_bad(*pmd))) return NULL; ptep = pte_offset_map(pmd, addr); @@ -389,6 +399,7 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) if (pte_present(pte)) page = pte_page(pte); pte_unmap(ptep); + return page; } EXPORT_SYMBOL(vmalloc_to_page); -- 2.7.4