From: Nicholas Piggin <npiggin@gmail.com>
To: linux-mm@kvack.org
Cc: Nicholas Piggin <npiggin@gmail.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Zefan Li <lizefan@huawei.com>
Subject: [PATCH v3 1/8] mm/vmalloc: fix vmalloc_to_page for huge vmap mappings
Date: Mon, 10 Aug 2020 12:27:25 +1000 [thread overview]
Message-ID: <20200810022732.1150009-2-npiggin@gmail.com> (raw)
In-Reply-To: <20200810022732.1150009-1-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>
---
mm/vmalloc.c | 40 ++++++++++++++++++++++++++--------------
1 file changed, 26 insertions(+), 14 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index b482d240f9a2..49f225b0f855 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -38,6 +38,7 @@
#include <linux/overflow.h>
#include <linux/uaccess.h>
+#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/shmparam.h>
@@ -343,7 +344,9 @@ 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 +366,33 @@ 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 +400,7 @@ 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);
--
2.23.0
next prev parent reply other threads:[~2020-08-10 2:27 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-10 2:27 [PATCH v3 0/8] huge vmalloc mappings Nicholas Piggin
2020-08-10 2:27 ` Nicholas Piggin [this message]
2020-08-10 2:27 ` [PATCH v3 2/8] mm: apply_to_pte_range warn and fail if a large pte is encountered Nicholas Piggin
2020-08-10 2:27 ` [PATCH v3 3/8] mm/vmalloc: rename vmap_*_range vmap_pages_*_range Nicholas Piggin
2020-08-10 2:27 ` [PATCH v3 4/8] lib/ioremap: rename ioremap_*_range to vmap_*_range Nicholas Piggin
2020-08-10 2:27 ` [PATCH v3 5/8] mm: HUGE_VMAP arch support cleanup Nicholas Piggin
2020-08-10 3:58 ` kernel test robot
2020-08-10 2:27 ` [PATCH v3 6/8] mm: Move vmap_range from lib/ioremap.c to mm/vmalloc.c Nicholas Piggin
2020-08-10 2:27 ` [PATCH v3 7/8] mm/vmalloc: add vmap_range_noflush variant Nicholas Piggin
2020-08-10 2:27 ` [PATCH v3 8/8] mm/vmalloc: Hugepage vmalloc mappings Nicholas Piggin
2020-08-12 12:25 ` Jonathan Cameron
2020-08-12 16:18 ` Jonathan Cameron
2020-08-11 16:32 ` [PATCH v3 0/8] huge " Jonathan Cameron
2020-08-12 1:07 ` Zefan Li
2020-08-12 8:11 ` Nicholas Piggin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200810022732.1150009-2-npiggin@gmail.com \
--to=npiggin@gmail.com \
--cc=bp@alien8.de \
--cc=catalin.marinas@arm.com \
--cc=hpa@zytor.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=lizefan@huawei.com \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).