mm/backing-dev.c: reset bdi min_ratio in bdi_unregister()
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 <peterz@infradead.org> Reported-by: Vito Caputo <lkml@pengaru.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -606,6 +606,7 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)
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void bdi_unregister(struct backing_dev_info *bdi)
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void bdi_unregister(struct backing_dev_info *bdi)
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{
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{
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if (bdi->dev) {
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if (bdi->dev) {
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bdi_set_min_ratio(bdi, 0);
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trace_writeback_bdi_unregister(bdi);
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trace_writeback_bdi_unregister(bdi);
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bdi_prune_sb(bdi);
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bdi_prune_sb(bdi);
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del_timer_sync(&bdi->wb.wakeup_timer);
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del_timer_sync(&bdi->wb.wakeup_timer);
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