writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth()
authorTejun Heo <tj@kernel.org>
Wed, 4 Mar 2015 15:37:43 +0000 (10:37 -0500)
committerJens Axboe <axboe@fb.com>
Wed, 4 Mar 2015 15:38:59 +0000 (08:38 -0700)
commit7d70e15480c0450d2bfafaad338a32e884fc215e
tree5f41bb2f4bb074959d30a51a1178d4c23411c2b3
parent13a7a6ac0a11197edcd0f756a035f472b42cdf8b
writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth()

global_update_bandwidth() uses static variable update_time as the
timestamp for the last update but forgets to initialize it to
INITIALIZE_JIFFIES.

This means that global_dirty_limit will be 5 mins into the future on
32bit and some large amount jiffies into the past on 64bit.  This
isn't critical as the only effect is that global_dirty_limit won't be
updated for the first 5 mins after booting on 32bit machines,
especially given the auxiliary nature of global_dirty_limit's role -
protecting against global dirty threshold's sudden dips; however, it
does lead to unintended suboptimal behavior.  Fix it.

Fixes: c42843f2f0bb ("writeback: introduce smoothed global dirty limit")
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
mm/page-writeback.c