On Sat, 30 Jun 2001, Marcelo Tosatti wrote:

> 
> 
> On Fri, 29 Jun 2001, Steve Lord wrote:
> 
> > 
> > Has anyone else seen a hang like this:
> > 
> >   bdflush()
> >     flush_dirty_buffers()
> >       ll_rw_block()
> >     submit_bh(buffer X)
> >       generic_make_request()
> >         __make_request()
> >             create_bounce()
> >               alloc_bounce_page()
> >                 alloc_page()
> >                   try_to_free_pages()
> >                     do_try_to_free_pages()
> >                       page_launder()
> >                         try_to_free_buffers( , 2)  -- i.e. wait for buffers
> >                           sync_page_buffers()
> >                             __wait_on_buffer(buffer X)
> > 
> > Where the buffer head X going in the top of the stack is the same as the one
> > we wait on at the bottom.
> > 
> > There still seems to be nothing to prevent the try to free buffers from
> > blocking on a buffer like this. Setting a flag on the buffer around the
> > create_bounce call, and skipping it in the try_to_free_buffers path would
> > be one approach to avoiding this.
> 
> Yes there is a bug: Linus is going to put a new fix soon. 
> 
> > I hit this in 2.4.6-pre6, and I don't see anything in the ac series to protect
> > against it.
> 
> Thats because the -ac series does not contain the __GFP_BUFFER/__GFP_IO
> moditications which are in the -ac series.
                                  ^^ 

I mean 2.4.6-pre, sorry.

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