From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Kirill A. Shutemov" Subject: Re: [PATCH v8 05/22] Add vm_replace_mixed() Date: Wed, 23 Jul 2014 18:55:00 +0300 Message-ID: <20140723155500.GA12790@node.dhcp.inet.fi> References: <20140723114540.GD10317@node.dhcp.inet.fi> <20140723135221.GA6754@linux.intel.com> <20140723142048.GA11963@node.dhcp.inet.fi> <20140723142745.GD6754@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org To: Matthew Wilcox Return-path: Content-Disposition: inline In-Reply-To: <20140723142745.GD6754@linux.intel.com> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Jul 23, 2014 at 10:27:45AM -0400, Matthew Wilcox wrote: > On Wed, Jul 23, 2014 at 05:20:48PM +0300, Kirill A. Shutemov wrote: > > On Wed, Jul 23, 2014 at 09:52:22AM -0400, Matthew Wilcox wrote: > > > I'd love to use a lighter-weight weapon! What would you recommend using, > > > zap_pte_range()? > > > > The most straight-forward way: extract body of pte cycle from > > zap_pte_range() to separate function -- zap_pte() -- and use it. > > OK, I can do that. What about the other parts of zap_page_range(), > do I need to call them? > > lru_add_drain(); No, I guess.. > tlb_gather_mmu(&tlb, mm, address, end); > tlb_finish_mmu(&tlb, address, end); New zap_pte() should tolerate tlb == NULL and does flush_tlb_page() or pte_clear_*flush or something. > update_hiwater_rss(mm); No: you cannot end up with lower rss after replace, iiuc. > mmu_notifier_invalidate_range_start(mm, address, end); > mmu_notifier_invalidate_range_end(mm, address, end); mmu_notifier_invalidate_page() should be enough. > > > if ((fd = open(argv[1], O_CREAT|O_RDWR, 0666)) < 0) { > > > perror(argv[1]); > > > exit(1); > > > } > > > > > > if (ftruncate(fd, 4096) < 0) { > > > > Shouldn't this be ftruncate(fd, 0)? Otherwise the memcpy() below will > > fault in page from backing storage, not hole and write will not replace > > anything. > > Ah, it was starting with a new file, hence the O_CREAT up above. Do you mean you pointed to new file all the time? O_CREAT doesn't truncate file if it exists, iirc. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org