mm/backing-dev.c: reset bdi min_ratio in bdi_unregister()
authorPeter Zijlstra <peterz@infradead.org>
Tue, 26 Jul 2011 00:11:57 +0000 (17:11 -0700)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 5 Aug 2011 04:58:39 +0000 (21:58 -0700)
commit650957da7699e730e78e82735b8c2595fcf7794a
tree1f44a3a822a79e5f89eb6c71427d2576a087e7d5
parentb045b9a265fb46d8197b7d78aff1a8f6ab8e23df
mm/backing-dev.c: reset bdi min_ratio in bdi_unregister()

commit ccb6108f5b0b541d3eb332c3a73e645c0f84278e upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
mm/backing-dev.c