Received-SPF: pass (google.com: domain of linux-kernel+bounces-25595-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Content-Type: text/plain;
	charset=us-ascii
Precedence: bulk
Mime-Version: 1.0
Subject: Re: [PATCH v3 2/3] arm64: mm: HVO: support BBM of vmemmap pgtable
 safely
From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <20240113094436.2506396-3-sunnanyong@huawei.com>
Date: Mon, 15 Jan 2024 10:38:07 +0800
Cc: Catalin Marinas <catalin.marinas@arm.com>,
 Will Deacon <will@kernel.org>,
 Mike Kravetz <mike.kravetz@oracle.com>,
 akpm@linux-foundation.org,
 anshuman.khandual@arm.com,
 willy@infradead.org,
 wangkefeng.wang@huawei.com,
 linux-arm-kernel@lists.infradead.org,
 linux-kernel@vger.kernel.org,
 linux-mm@kvack.org
Content-Transfer-Encoding: 7bit
Message-Id: <C34E859F-52FD-43C8-A1AA-554FC560663F@linux.dev>
References: <20240113094436.2506396-1-sunnanyong@huawei.com>
 <20240113094436.2506396-3-sunnanyong@huawei.com>
To: Nanyong Sun <sunnanyong@huawei.com>


> On Jan 13, 2024, at 17:44, Nanyong Sun <sunnanyong@huawei.com> wrote:
> 
> Implement vmemmap_update_pmd and vmemmap_update_pte on arm64 to do
> BBM(break-before-make) logic when change the page table of vmemmap
> address, they will under the init_mm.page_table_lock.
> If a translation fault of vmemmap address concurrently happened after
> pte/pmd cleared, vmemmap page fault handler will acquire the
> init_mm.page_table_lock to wait for vmemmap update to complete,
> by then the virtual address is valid again, so PF can return and
> access can continue.
> In other case, do the traditional kernel fault.
> 
> Implement vmemmap_flush_tlb_all/range on arm64 with nothing
> to do because tlb already flushed in every single BBM.
> 
> Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks.