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Date: Wed, 4 Mar 2015 10:37:43 -0500 From: Tejun Heo <tj@...nel.org> To: Jens Axboe <axboe@...nel.dk> Cc: Jan Kara <jack@...e.cz>, Wu Fengguang <fengguang.wu@...el.com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org, linux-fsdevel@...r.kernel.org Subject: [PATCH block/for-4.0-fixes] writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth() Subject: 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@...nel.org> Acked-by: Jan Kara <jack@...e.cz> Cc: Wu Fengguang <fengguang.wu@...el.com> Cc: Jens Axboe <axboe@...nel.dk> Cc: stable@...r.kernel.org --- Added the "fixes" tag. Jens, can you please route this one? Thanks. mm/page-writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -922,7 +922,7 @@ static void global_update_bandwidth(unsi 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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