[PATCH 0/6] More graceful flusher thread memory reclaim wakeup
From: Jens Axboe
Date: Tue Sep 19 2017 - 15:53:17 EST
We've had some issues with writeback in presence of memory reclaim
at Facebook, and this patch set attempts to fix it up. The real
functional change is the last patch in the series, the first 5 are
prep and cleanup patches.
The basic idea is that we have callers that call
wakeup_flusher_threads() with nr_pages == 0. This means 'writeback
everything'. For memory reclaim situations, we can end up queuing
a TON of these kinds of writeback units. This can cause softlockups
and further memory issues, since we allocate huge amounts of
struct wb_writeback_work to handle this writeback. Handle this
situation more gracefully.