Re: [PATCH v2 1/3] mm: document zone device struct page field usage
From: Matthew Wilcox
Date: Mon Jul 22 2019 - 07:08:29 EST
On Sun, Jul 21, 2019 at 10:13:45PM -0700, Ira Weiny wrote:
> On Sun, Jul 21, 2019 at 09:02:04AM -0700, Matthew Wilcox wrote:
> > On Fri, Jul 19, 2019 at 12:29:53PM -0700, Ralph Campbell wrote:
> > > Struct page for ZONE_DEVICE private pages uses the page->mapping and
> > > and page->index fields while the source anonymous pages are migrated to
> > > device private memory. This is so rmap_walk() can find the page when
> > > migrating the ZONE_DEVICE private page back to system memory.
> > > ZONE_DEVICE pmem backed fsdax pages also use the page->mapping and
> > > page->index fields when files are mapped into a process address space.
> > >
> > > Restructure struct page and add comments to make this more clear.
> > NAK. I just got rid of this kind of foolishness from struct page,
> > and you're making it harder to understand, not easier. The comments
> > could be improved, but don't lay it out like this again.
> Was V1 of Ralphs patch ok? It seemed ok to me.
Yes, v1 was fine. This seems like a regression.