diff options
author | Nicholas Piggin <npiggin@gmail.com> | 2021-04-29 22:58:13 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-30 11:20:39 -0700 |
commit | c0eb315ad9719e41ce44708455cc69df7ac9f3f8 (patch) | |
tree | 8de836d37d5e4d0d8c2f15c309b303cd56e325c1 | |
parent | 972472c7466b50efed4539694007951a3fc7b95c (diff) |
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 <npiggin@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ding Tianhong <dingtianhong@huawei.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | arch/sparc/include/asm/pgtable_32.h | 3 | ||||
-rw-r--r-- | 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 632cdb959542..a5cf79c149fe 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 8c20670e246d..ee865b6e88eb 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -34,7 +34,7 @@ #include <linux/bitops.h> #include <linux/rbtree_augmented.h> #include <linux/overflow.h> - +#include <linux/pgtable.h> #include <linux/uaccess.h> #include <asm/tlbflush.h> #include <asm/shmparam.h> @@ -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); |