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[70.31.27.79]) by smtp.gmail.com with ESMTPSA id n1-20020a05620a294100b006fa16fe93bbsm11313013qkp.15.2022.11.29.11.35.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Nov 2022 11:35:43 -0800 (PST) From: Peter Xu To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: James Houghton , Jann Horn , peterx@redhat.com, Andrew Morton , Andrea Arcangeli , Rik van Riel , Nadav Amit , Miaohe Lin , Muchun Song , Mike Kravetz , David Hildenbrand Subject: [PATCH 09/10] mm/hugetlb: Make page_vma_mapped_walk() safe to pmd unshare Date: Tue, 29 Nov 2022 14:35:25 -0500 Message-Id: <20221129193526.3588187-10-peterx@redhat.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221129193526.3588187-1-peterx@redhat.com> References: <20221129193526.3588187-1-peterx@redhat.com> MIME-Version: 1.0 Content-type: text/plain Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since page_vma_mapped_walk() walks the pgtable, it needs the vma lock to make sure the pgtable page will not be freed concurrently. Signed-off-by: Peter Xu --- include/linux/rmap.h | 4 ++++ mm/page_vma_mapped.c | 5 ++++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/rmap.h b/include/linux/rmap.h index bd3504d11b15..a50d18bb86aa 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -13,6 +13,7 @@ #include #include #include +#include /* * The anon_vma heads a list of private "related" vmas, to scan if @@ -408,6 +409,9 @@ static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw) pte_unmap(pvmw->pte); if (pvmw->ptl) spin_unlock(pvmw->ptl); + /* This needs to be after unlock of the spinlock */ + if (is_vm_hugetlb_page(pvmw->vma)) + hugetlb_vma_unlock_read(pvmw->vma); } bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw); diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c index 93e13fc17d3c..f94ec78b54ff 100644 --- a/mm/page_vma_mapped.c +++ b/mm/page_vma_mapped.c @@ -169,10 +169,13 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw) if (pvmw->pte) return not_found(pvmw); + hugetlb_vma_lock_read(vma); /* when pud is not present, pte will be NULL */ pvmw->pte = huge_pte_offset(mm, pvmw->address, size); - if (!pvmw->pte) + if (!pvmw->pte) { + hugetlb_vma_unlock_read(vma); return false; + } pvmw->ptl = huge_pte_lock(hstate, mm, pvmw->pte); if (!check_pte(pvmw)) -- 2.37.3