Re: [patch 3/3] mm: vmscan: clean up struct scan_control

From: Andrew Morton
Date: Mon Jul 14 2014 - 15:56:43 EST

On Mon, 14 Jul 2014 09:20:49 -0400 Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> Reorder the members by input and output, then turn the individual
> integers for may_writepage, may_unmap, may_swap, compaction_ready,
> hibernation_mode into flags that fit into a single integer.

bitfields would be a pretty good fit here. I usually don't like them
because of locking concerns with the RMWs, but scan_control is never
accessed from another thread.

> - if (!sc->may_unmap && page_mapped(page))
> + if (!(sc->flags & MAY_UNMAP) && page_mapped(page))

Then edits such as this are unneeded.

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