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Shutemov" To: Li Xinhai Cc: linux-mm@kvack.org, Jan Kara Subject: Re: [PATCH] mm/memory.c: avoid repeated set_page_dirty in fault_dirty_shared_page Message-ID: <20191212165520.g6rpzvvlyi5wszw6@box> References: <1576164078-28402-1-git-send-email-lixinhai.lxh@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1576164078-28402-1-git-send-email-lixinhai.lxh@gmail.com> User-Agent: NeoMutt/20180716 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Dec 12, 2019 at 11:21:18PM +0800, Li Xinhai wrote: > When vm_ops->page_mkwrite is defined, and called from wp_page_shared and > do_shared_fault, the set_page_dirty must already called by page_mkwrite. Must? Do all ->page_mkwrite implementation do this? > @@ -3645,7 +3646,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf) > * Check if the backing address space wants to know that the page is > * about to become writable > */ > - if (vma->vm_ops->page_mkwrite) { > + if (vma->vm_ops && vma->vm_ops->page_mkwrite) { vma->vm_ops is always non-NULL here. -- Kirill A. Shutemov