On Fri, 28 Sep 2001, Andrea Arcangeli wrote:
> Moving clear_bit just above submit_bh will fix it (please Robert make
> this change before testing it), because if we block in submit_bh in the
> bounce, then we won't deadlock on ourself because of the pagehighmem
We won't block on _ourselves_, but we can block on _two_ people doing it,
and blocking on each others requests that are blocked waiting on a bounce
buffer. Both will have one locked buffer, both will be waiting for the
other person unlocking that buffer, and neither will ever make progress.
You could clear that bit _after_ the bounce buffer allocation, I suspect.
But I also suspect that it doesn't matter much, and as I can imagine
similar problems with GFP_NOIO and loopback etc (do you see any reason why
loopback couldn't deadlock on waiting for itself?), I think the GFP_XXX
thing is the proper fix.
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This archive was generated by hypermail 2b29 : Sun Sep 30 2001 - 21:00:59 EST