From: Mike Rapoport <rppt@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Christopher Lameter <cl@linux.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
Elena Reshetova <elena.reshetova@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
James Bottomley <jejb@linux.ibm.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Mark Rutland <mark.rutland@arm.com>,
Michal Hocko <mhocko@suse.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Mike Rapoport <rppt@kernel.org>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Roman Gushchin <guro@fb.com>, Shakeel Butt <shakeelb@google.com>,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tycho Andersen <tycho@tycho.ws>, Will Deacon <will@kernel.org>,
Yury Norov <yury.norov@gmail.com>,
linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org,
x86@kernel.org
Subject: [PATCH v3 1/2] secretmem/gup: don't check if page is secretmem without reference
Date: Tue, 20 Apr 2021 18:00:48 +0300 [thread overview]
Message-ID: <20210420150049.14031-2-rppt@kernel.org> (raw)
In-Reply-To: <20210420150049.14031-1-rppt@kernel.org>
From: Mike Rapoport <rppt@linux.ibm.com>
The check in gup_pte_range() whether a page belongs to a secretmem mapping
is performed before grabbing the page reference.
To avoid potential race move the check after try_grab_compound_head().
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
mm/gup.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/gup.c b/mm/gup.c
index c3a17b189064..6515f82b0f32 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2080,13 +2080,15 @@ 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);
- if (page_is_secretmem(page))
- goto pte_unmap;
-
head = try_grab_compound_head(page, 1, flags);
if (!head)
goto pte_unmap;
+ if (unlikely(page_is_secretmem(page))) {
+ put_compound_head(head, 1, flags);
+ goto pte_unmap;
+ }
+
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
put_compound_head(head, 1, flags);
goto pte_unmap;
--
2.28.0
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next prev parent reply other threads:[~2021-04-20 15:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 15:00 [PATCH v3 0/2] secretmem: optimize page_is_secretmem() Mike Rapoport
2021-04-20 15:00 ` Mike Rapoport [this message]
2021-04-20 15:17 ` [PATCH v3 1/2] secretmem/gup: don't check if page is secretmem without reference David Hildenbrand
2021-04-20 15:00 ` [PATCH v3 2/2] secretmem: optimize page_is_secretmem() Mike Rapoport
2021-05-07 15:01 ` Matthew Wilcox
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