From: Peter Zijlstra <[email protected]> Vito said:
: The system has many usb disks coming and going day to day, with their : respective bdi's having min_ratio set to 1 when inserted. It works for : some time until eventually min_ratio can no longer be set, even when the : active set of bdi's seen in /sys/class/bdi/*/min_ratio doesn't add up to : anywhere near 100. : : This then leads to an unrelated starvation problem caused by write-heavy : fuse mounts being used atop the usb disks, a problem the min_ratio setting : at the underlying devices bdi effectively prevents. Fix this leakage by resetting the bdi min_ratio when unregistering the BDI. Signed-off-by: Peter Zijlstra <[email protected]> Reported-by: Vito Caputo <[email protected]> Cc: Wu Fengguang <[email protected]> Cc: Miklos Szeredi <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- mm/backing-dev.c | 1 + 1 file changed, 1 insertion(+) diff -puN mm/backing-dev.c~bdi_min_ratio-never-shrinks-ultimately-preventing-valid-setting-of-min_ratio mm/backing-dev.c --- a/mm/backing-dev.c~bdi_min_ratio-never-shrinks-ultimately-preventing-valid-setting-of-min_ratio +++ a/mm/backing-dev.c @@ -606,6 +606,7 @@ static void bdi_prune_sb(struct backing_ void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { + bdi_set_min_ratio(bdi, 0); trace_writeback_bdi_unregister(bdi); bdi_prune_sb(bdi); del_timer_sync(&bdi->wb.wakeup_timer); _ _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
