Messages in this thread | | | Date | Sat, 30 Jun 2001 15:29:17 -0300 (BRT) | From | Marcelo Tosatti <> | Subject | Re: Bounce buffer deadlock |
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On Sat, 30 Jun 2001, Steve Lord wrote:
> > > Yes. 2.4.6-pre8 fixes that (not sure if its up already). > > It is up. > > > > > > If the fix is to avoid page_launder in these cases then the number of > > > occurrences when an alloc_pages fails will go up. > > > > > I was attempting to come up with a way of making try_to_free_buffers > > > fail on buffers which are being processed in the generic_make_request > > > path by marking them, the problem is there is no single place to reset > > > the state of a buffer so that try_to_free_buffers will wait for it. > > > Doing it after the end of the loop in generic_make_request is race > > > prone to say the least. > > > > I really want to fix things like this in 2.5. (ie not avoid the deadlock > > by completly avoiding physical IO, but avoid the deadlock by avoiding > > physical IO on the "device" which is doing the allocation) > > > > Could you send me your code ? No problem if it does not work at all :) > > > > Well, the basic idea is simple, but I suspect the implementation might > rapidly become historical in 2.5. Basically I added a new buffer state bit, > although BH_Req looks like it could be cannibalized, no one appears to check > for it (is it really dead code?).
Dunno. Ask Jens :)
> Using a flag to skip buffers in try_to_free_buffers is easy:
I was thinking more about skipping the buffers which are "owned" by the device which is doing the allocation.
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