From: Tejun Heo Date: Wed, 4 Mar 2015 15:37:43 +0000 (-0500) Subject: writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() X-Git-Tag: v3.12.41~59 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0d4958ffdbf7a14e58ea822968a40c05b3c9de0f;p=thirdparty%2Fkernel%2Fstable.git writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() commit 7d70e15480c0450d2bfafaad338a32e884fc215e upstream. 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 Acked-by: Jan Kara Cc: Wu Fengguang Cc: Jens Axboe Signed-off-by: Jens Axboe Signed-off-by: Jiri Slaby --- diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 9f45f87a58595..d3653325a2550 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -943,7 +943,7 @@ static void global_update_bandwidth(unsigned long thresh, unsigned long now) { static DEFINE_SPINLOCK(dirty_lock); - static unsigned long update_time; + static unsigned long update_time = INITIAL_JIFFIES; /* * check locklessly first to optimize away locking for the most time