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)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 26 Jul 2011 03:57:07 +0000 (20:57 -0700)
commitccb6108f5b0b541d3eb332c3a73e645c0f84278e
tree4c0a5c8bc1165d574e5cf4c023cefa13e9454b04
parent2b934c6236983392d01bef22e43af3051cac16f5
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>
mm/backing-dev.c