From: Nicholas Piggin <npiggin@gmail.com>
To: linux-mm@kvack.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org,
Andrew Morton <akpm@linux-foundation.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH 3/3] mm/vmalloc: fix vmalloc_to_page for huge vmap mappings
Date: Sun, 23 Jun 2019 19:44:46 +1000 [thread overview]
Message-ID: <20190623094446.28722-4-npiggin@gmail.com> (raw)
In-Reply-To: <20190623094446.28722-1-npiggin@gmail.com>
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")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
include/asm-generic/4level-fixup.h | 1 +
include/asm-generic/5level-fixup.h | 1 +
mm/vmalloc.c | 37 +++++++++++++++++++-----------
3 files changed, 26 insertions(+), 13 deletions(-)
diff --git a/include/asm-generic/4level-fixup.h b/include/asm-generic/4level-fixup.h
index e3667c9a33a5..3cc65a4dd093 100644
--- a/include/asm-generic/4level-fixup.h
+++ b/include/asm-generic/4level-fixup.h
@@ -20,6 +20,7 @@
#define pud_none(pud) 0
#define pud_bad(pud) 0
#define pud_present(pud) 1
+#define pud_large(pud) 0
#define pud_ERROR(pud) do { } while (0)
#define pud_clear(pud) pgd_clear(pud)
#define pud_val(pud) pgd_val(pud)
diff --git a/include/asm-generic/5level-fixup.h b/include/asm-generic/5level-fixup.h
index bb6cb347018c..c4377db09a4f 100644
--- a/include/asm-generic/5level-fixup.h
+++ b/include/asm-generic/5level-fixup.h
@@ -22,6 +22,7 @@
#define p4d_none(p4d) 0
#define p4d_bad(p4d) 0
#define p4d_present(p4d) 1
+#define p4d_large(p4d) 0
#define p4d_ERROR(p4d) do { } while (0)
#define p4d_clear(p4d) pgd_clear(p4d)
#define p4d_val(p4d) pgd_val(p4d)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4c9e150e5ad3..4be98f700862 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -36,6 +36,7 @@
#include <linux/rbtree_augmented.h>
#include <linux/uaccess.h>
+#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/shmparam.h>
@@ -284,26 +285,36 @@ struct page *vmalloc_to_page(const void *vmalloc_addr)
if (pgd_none(*pgd))
return NULL;
+
p4d = p4d_offset(pgd, addr);
if (p4d_none(*p4d))
return NULL;
- pud = pud_offset(p4d, addr);
+ if (WARN_ON_ONCE(p4d_bad(*p4d)))
+ return NULL;
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+ if (p4d_large(*p4d))
+ return p4d_page(*p4d) + ((addr & ~P4D_MASK) >> PAGE_SHIFT);
+#endif
- /*
- * 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 (WARN_ON_ONCE(pud_bad(*pud)))
return NULL;
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+ if (pud_large(*pud))
+ return pud_page(*pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
+#endif
+
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 (WARN_ON_ONCE(pmd_bad(*pmd)))
return NULL;
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+ if (pmd_large(*pmd))
+ return pmd_page(*pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+#endif
ptep = pte_offset_map(pmd, addr);
pte = *ptep;
--
2.20.1
next prev parent reply other threads:[~2019-06-23 9:45 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-23 9:44 [PATCH 0/3] fix vmalloc_to_page for huge vmap mappings Nicholas Piggin
2019-06-23 9:44 ` [PATCH 1/3] arm64: mm: Add p?d_large() definitions Nicholas Piggin
2019-07-01 9:27 ` Will Deacon
2019-07-01 10:03 ` Steven Price
2019-07-01 10:15 ` Will Deacon
2019-07-02 3:07 ` Nicholas Piggin
2019-07-02 10:46 ` Will Deacon
2019-06-23 9:44 ` [PATCH 2/3] powerpc/64s: Add p?d_large definitions Nicholas Piggin
2019-06-23 9:44 ` Nicholas Piggin [this message]
2019-06-24 6:52 ` [PATCH 3/3] mm/vmalloc: fix vmalloc_to_page for huge vmap mappings Anshuman Khandual
2019-06-25 0:20 ` Nicholas Piggin
2019-06-24 5:52 ` [PATCH 0/3] " Anshuman Khandual
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