Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   yulei.kernel@gmail.com
To:     linux-mm@kvack.org, akpm@linux-foundation.org,
        linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, naoya.horiguchi@nec.com,
        viro@zeniv.linux.org.uk, pbonzini@redhat.com
Cc:     joao.m.martins@oracle.com, rdunlap@infradead.org,
        sean.j.christopherson@intel.com, xiaoguangrong.eric@gmail.com,
        kernellwp@gmail.com, lihaiwei.kernel@gmail.com,
        Yulei Zhang <yuleixzhang@tencent.com>,
        Chen Zhuo <sagazchen@tencent.com>
Subject: [RFC V2 20/37] mm: support dmem huge pmd for vmf_insert_pfn_pmd()
Date:   Mon,  7 Dec 2020 19:31:13 +0800
Message-Id: <d9a59ce61973e9fcf562311f02614a5f9d124937.1607332046.git.yuleixzhang@tencent.com>
In-Reply-To: <cover.1607332046.git.yuleixzhang@tencent.com>
References: <cover.1607332046.git.yuleixzhang@tencent.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Yulei Zhang <yuleixzhang@tencent.com>

Since vmf_insert_pfn_pmd will BUG_ON non-pmd-devmap, we make pfn dmem pass
the check.

Dmem huge pmd will be marked with _PAGE_SPECIAL and _PAGE_DMEM, so that
follow_pfn() could recognize it.

Signed-off-by: Chen Zhuo <sagazchen@tencent.com>
Signed-off-by: Yulei Zhang <yuleixzhang@tencent.com>
---
 mm/huge_memory.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2a818ec..6e52d57 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -781,6 +781,8 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
 	if (pfn_t_devmap(pfn))
 		entry = pmd_mkdevmap(entry);
+	else if (pfn_t_dmem(pfn))
+		entry = pmd_mkdmem(entry);
 	if (write) {
 		entry = pmd_mkyoung(pmd_mkdirty(entry));
 		entry = maybe_pmd_mkwrite(entry, vma);
@@ -827,7 +829,7 @@ vm_fault_t vmf_insert_pfn_pmd_prot(struct vm_fault *vmf, pfn_t pfn,
 	 * can't support a 'special' bit.
 	 */
 	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) &&
-			!pfn_t_devmap(pfn));
+			!pfn_t_devmap(pfn) && !pfn_t_dmem(pfn));
 	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 						(VM_PFNMAP|VM_MIXEDMAP));
 	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
-- 
1.8.3.1