On Fri, Jul 29, 2022 at 10:22:16AM +0100, Mel Gorman wrote:

There is some context missing because it's not clear what the full impact is
but it is definitly the case that writepage is ignored in some contexts for
common filesystems so lets assume that writepage from reclaim context always
failed as a worst case scenario. Certainly this type of change is something
linux-mm needs to be aware of because we've been blind-sided before.

Between willy and Johannes pushing or it I was under the strong assumption
that linux-mm knows of it..

I don't think it would be incredibly damaging although there *might* be
issues with small systems or cgroups. 

Johannes specifically mentioned that cgroup writeback will never call
into ->writepage anyway.