diff options
| -rw-r--r-- | mm/page-writeback.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 601a5e048d12..c1a4b32af1a7 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1858,6 +1858,27 @@ free_running: break; } + /* + * Unconditionally start background writeback if it's not + * already in progress. We need to do this because the global + * dirty threshold check above (nr_dirty > gdtc->bg_thresh) + * doesn't account for these cases: + * + * a) strictlimit BDIs: throttling is calculated using per-wb + * thresholds. The per-wb threshold can be exceeded even when + * nr_dirty < gdtc->bg_thresh + * + * b) memcg-based throttling: memcg uses its own dirty count and + * thresholds and can trigger throttling even when global + * nr_dirty < gdtc->bg_thresh + * + * Writeback needs to be started else the writer stalls in the + * throttle loop waiting for dirty pages to be written back + * while no writeback is running. + */ + if (unlikely(!writeback_in_progress(wb))) + wb_start_background_writeback(wb); + mem_cgroup_flush_foreign(wb); /* |