On Fri, Jun 11, 2010 at 12:29:12PM -0400, Christoph Hellwig wrote: > On Tue, Jun 08, 2010 at 10:28:14AM +0100, Mel Gorman wrote: > > > - we also need to care about ->releasepage. At least for XFS it > > > can end up in the same deep allocator chain as ->writepage because > > > it does all the extent state conversions, even if it doesn't > > > start I/O. > > > > Dang. > > > > > I haven't managed yet to decode the ext4/btrfs codepaths > > > for ->releasepage yet to figure out how they release a page that > > > covers a delayed allocated or unwritten range. > > > > > > > If ext4/btrfs are also very deep call-chains and this series is going more > > or less the right direction, then avoiding calling ->releasepage from direct > > reclaim is one, somewhat unfortunate, option. The second is to avoid it on > > a per-filesystem basis for direct reclaim using PF_MEMALLOC to detect > > reclaimers and PF_KSWAPD to tell the difference between direct > > reclaimers and kswapd. > > I went throught this a bit more and I can't actually hit that code in > XFS ->releasepage anymore. I've also audited the caller and can't see > how we could theoretically hit it anymore. Do the VM gurus know a case > where we would call ->releasepage on a page that's actually dirty and > hasn't been through block_invalidatepage before? > Not a clue I'm afraid as I haven't dealt much with the interactions between VM and FS in the past. Nick? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>