Re: sk_lock: inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage

[KOSAKI Motohiro <kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org>]

> On Mon, Jun 08, 2009 at 12:55:18PM +0800, KOSAKI Motohiro wrote:
> > Hi
> > 
> > > Hi,
> > > 
> > > This lockdep warning appears when doing stress memory tests over NFS.
> > > 
> > > page reclaim => nfs_writepage => tcp_sendmsg => lock sk_lock
> > > 
> > > tcp_close => lock sk_lock => tcp_send_fin => alloc_skb_fclone => page reclaim
> > > 
> > > Any ideas?
> > 
> > AFAIK, btrfs has re-dirty hack. 
> > 
> > ------------------------------------------------------------------
> > static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
> > {
> >         struct extent_io_tree *tree;
> > 
> > 
> >         if (current->flags & PF_MEMALLOC) {
> >                 redirty_page_for_writepage(wbc, page);
> >                 unlock_page(page);
> >                 return 0;
> >         }
> >         tree = &BTRFS_I(page->mapping->host)->io_tree;
> >         return extent_write_full_page(tree, page, btrfs_get_extent, wbc);
> > }
> > ---------------------------------------------------------------
> > 
> > PF_MEMALLOC mean caller is try_to_free_pages(). (not normal write nor kswapd)
> 
> No, kswapd also sets the PF_MEMALLOC flag. It looks like btrfs_writepage()
> is trying to avoid inefficient page outs at the cost of pinning dirty
> pages in memory (even when we really want free pages).

Sorry, I was confused ;)