From: Pingfan Liu <kernelfans@gmail.com>
To: linux-mm@kvack.org
Cc: Pingfan Liu <kernelfans@gmail.com>,
Ira Weiny <ira.weiny@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@linux.ibm.com>,
Dan Williams <dan.j.williams@intel.com>,
Matthew Wilcox <willy@infradead.org>,
John Hubbard <jhubbard@nvidia.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Keith Busch <keith.busch@intel.com>,
Christoph Hellwig <hch@infradead.org>,
Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [PATCHv4 2/3] mm/gup: fix omission of check on FOLL_LONGTERM in gup fast path
Date: Thu, 13 Jun 2019 18:45:01 +0800 [thread overview]
Message-ID: <1560422702-11403-3-git-send-email-kernelfans@gmail.com> (raw)
In-Reply-To: <1560422702-11403-1-git-send-email-kernelfans@gmail.com>
FOLL_LONGTERM suggests a pin which is going to be given to hardware and
can't move. It would truncate CMA permanently and should be excluded.
FOLL_LONGTERM has already been checked in the slow path, but not checked in
the fast path, which means a possible leak of CMA page to longterm pinned
requirement through this crack.
Place a check in gup_pte_range() in the fast path.
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
mm/gup.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/mm/gup.c b/mm/gup.c
index 766ae54..de1b03f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1757,6 +1757,14 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
page = pte_page(pte);
+ /*
+ * FOLL_LONGTERM suggests a pin given to hardware. Prevent it
+ * from truncating CMA area
+ */
+ if (unlikely(flags & FOLL_LONGTERM) &&
+ is_migrate_cma_page(page))
+ goto pte_unmap;
+
head = try_get_compound_head(page, 1);
if (!head)
goto pte_unmap;
@@ -1900,6 +1908,12 @@ static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
refs++;
} while (addr += PAGE_SIZE, addr != end);
+ if (unlikely(flags & FOLL_LONGTERM) &&
+ is_migrate_cma_page(page)) {
+ *nr -= refs;
+ return 0;
+ }
+
head = try_get_compound_head(pmd_page(orig), refs);
if (!head) {
*nr -= refs;
@@ -1941,6 +1955,12 @@ static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
refs++;
} while (addr += PAGE_SIZE, addr != end);
+ if (unlikely(flags & FOLL_LONGTERM) &&
+ is_migrate_cma_page(page)) {
+ *nr -= refs;
+ return 0;
+ }
+
head = try_get_compound_head(pud_page(orig), refs);
if (!head) {
*nr -= refs;
@@ -1978,6 +1998,12 @@ static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
refs++;
} while (addr += PAGE_SIZE, addr != end);
+ if (unlikely(flags & FOLL_LONGTERM) &&
+ is_migrate_cma_page(page)) {
+ *nr -= refs;
+ return 0;
+ }
+
head = try_get_compound_head(pgd_page(orig), refs);
if (!head) {
*nr -= refs;
--
2.7.5
next prev parent reply other threads:[~2019-06-13 15:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-13 10:44 [PATCHv4 0/3] mm/gup: fix omission of check on FOLL_LONGTERM in gup fast path Pingfan Liu
2019-06-13 10:45 ` [PATCHv4 1/3] mm/gup: rename nr as nr_pinned in get_user_pages_fast() Pingfan Liu
2019-06-13 21:28 ` Ira Weiny
2019-06-13 10:45 ` Pingfan Liu [this message]
2019-06-13 21:39 ` [PATCHv4 2/3] mm/gup: fix omission of check on FOLL_LONGTERM in gup fast path Ira Weiny
2019-06-14 15:24 ` Pingfan Liu
2019-06-13 10:45 ` [PATCHv4 3/3] mm/gup_benchemark: add LONGTERM_BENCHMARK test " Pingfan Liu
2019-06-13 21:42 ` Ira Weiny
2019-06-13 21:49 ` Ira Weiny
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