Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Sun, 28 May 2023 23:14:48 -0700 (PDT)
From:   Hugh Dickins <hughd@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        David Hildenbrand <david@redhat.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Qi Zheng <zhengqi.arch@bytedance.com>,
        Yang Shi <shy828301@gmail.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Peter Xu <peterx@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>, Yu Zhao <yuzhao@google.com>,
        Alistair Popple <apopple@nvidia.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Steven Price <steven.price@arm.com>,
        SeongJae Park <sj@kernel.org>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Zack Rusin <zackr@vmware.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Pasha Tatashin <pasha.tatashin@soleen.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Minchan Kim <minchan@kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
        Song Liu <song@kernel.org>,
        Thomas Hellstrom <thomas.hellstrom@linux.intel.com>,
        Russell King <linux@armlinux.org.uk>,
        "David S. Miller" <davem@davemloft.net>,
        Michael Ellerman <mpe@ellerman.id.au>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Jann Horn <jannh@google.com>,
        linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 01/12] mm/pgtable: add rcu_read_lock() and
 rcu_read_unlock()s
In-Reply-To: <35e983f5-7ed3-b310-d949-9ae8b130cdab@google.com>
Message-ID: <88c445ae-552-5243-31a4-2674bac62d4d@google.com>
References: <35e983f5-7ed3-b310-d949-9ae8b130cdab@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

Before putting them to use (several commits later), add rcu_read_lock()
to pte_offset_map(), and rcu_read_unlock() to pte_unmap().  Make this a
separate commit, since it risks exposing imbalances: prior commits have
fixed all the known imbalances, but we may find some have been missed.

Signed-off-by: Hugh Dickins <hughd@google.com>
---
 include/linux/pgtable.h | 4 ++--
 mm/pgtable-generic.c    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index a1326e61d7ee..8b0fc7fdc46f 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -99,7 +99,7 @@ static inline pte_t *pte_offset_kernel(pmd_t *pmd, unsigned long address)
 	((pte_t *)kmap_local_page(pmd_page(*(pmd))) + pte_index((address)))
 #define pte_unmap(pte)	do {	\
 	kunmap_local((pte));	\
-	/* rcu_read_unlock() to be added later */	\
+	rcu_read_unlock();	\
 } while (0)
 #else
 static inline pte_t *__pte_map(pmd_t *pmd, unsigned long address)
@@ -108,7 +108,7 @@ static inline pte_t *__pte_map(pmd_t *pmd, unsigned long address)
 }
 static inline void pte_unmap(pte_t *pte)
 {
-	/* rcu_read_unlock() to be added later */
+	rcu_read_unlock();
 }
 #endif
 
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index c7ab18a5fb77..674671835631 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -236,7 +236,7 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp)
 {
 	pmd_t pmdval;
 
-	/* rcu_read_lock() to be added later */
+	rcu_read_lock();
 	pmdval = pmdp_get_lockless(pmd);
 	if (pmdvalp)
 		*pmdvalp = pmdval;
@@ -250,7 +250,7 @@ pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp)
 	}
 	return __pte_map(&pmdval, addr);
 nomap:
-	/* rcu_read_unlock() to be added later */
+	rcu_read_unlock();
 	return NULL;
 }
 
-- 
2.35.3