From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 26 Mar 2004 18:58:42 +0100 From: Andrea Arcangeli Subject: Re: [RFC][PATCH 1/3] radix priority search tree - objrmap complexity fix Message-ID: <20040326175842.GC9604@dualathlon.random> References: <20040325225919.GL20019@dualathlon.random> <20040326075343.GB12484@dualathlon.random> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Rajesh Venkatasubramanian Cc: akpm@osdl.org, torvalds@osdl.org, hugh@veritas.com, mbligh@aracnet.com, riel@redhat.com, mingo@elte.hu, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Fri, Mar 26, 2004 at 10:43:17AM -0500, Rajesh Venkatasubramanian wrote: > > Hi Andrea, > > There is a problem with the prio_tree merge. As usual it is > related to VM_NONLINEAR. When I was reading Hugh's nonlinear > patch, I recalled this problem. > > Currently, with the prio_tree search in try_to_unmap, you will > not check all the nonlinear vmas. Earlier, with a list walk it > was not a problem. But, now in try_to_unmap we only select vmas > that map a given page. That's meaningless for nonlinear vmas. > > I think the fix is straight-forward. My plan is to add a > "list_head i_mmap_nonlinear" to the address_space and use the > list to find all nonlinear vmas in try_to_unmap_inode. > > In sys_remap_file_pages, we can do something like below: > > if (!(vma->vm_flags & VM_NONLINEAR)) { /* vma is not already nonlinear */ > __vma_prio_tree_remove(&mapping->i_mmap_shared, vma) > list_add_tail(&vma->shared.vm_set.list, > &mapping->i_mmap_nonlinear); > } > > Urggh. That forces us to take i_shared_sem in sys_remap_file_pages. > > Please let me know if you have any better idea. Otherwise, tonite > I will send you a patch for 2.6.5-rc2-aa4. I agree this will fix it. If a better fix comes to mind I will let you know, in the meantime this fix will be welcome (despite the i_mmap_sem in remap_file_pages) and I will merge it in the next prio-tree patch. Thanks! -- 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: aart@kvack.org