On Tue 17-01-17 17:16:19, Michal Hocko wrote: > > > But before going to play with that I am really wondering whether we need > > > all this with no journal at all. AFAIU what Jack told me it is the > > > journal lock(s) which is the biggest problem from the reclaim recursion > > > point of view. What would cause a deadlock in no journal mode? > > > > We still have the original problem for why we need GFP_NOFS even in > > ext2. If we are in a writeback path, and we need to allocate memory, > > we don't want to recurse back into the file system's writeback path. > > But we do not enter the writeback path from the direct reclaim. Or do > you mean something other than pageout()'s mapping->a_ops->writepage? > There is only try_to_release_page where we get back to the filesystems > but I do not see any NOFS protection in ext4_releasepage. Maybe to expand a bit: These days, direct reclaim can call ->releasepage() callback, ->evict_inode() callback (and only for inodes with i_nlink > 0), shrinkers. That's it. So the recursion possibilities are rather more limited than they used to be several years ago and we likely do not need as much GFP_NOFS protection as we used to. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>