This is a note to let you know that I've just added the patch titled
writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth()
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
writeback-add-missing-initial_jiffies-init-in-global_update_bandwidth.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7d70e15480c0450d2bfafaad338a32e884fc215e Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@xxxxxxxxxx>
Date: Wed, 4 Mar 2015 10:37:43 -0500
Subject: writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth()
From: Tejun Heo <tj@xxxxxxxxxx>
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 <tj@xxxxxxxxxx>
Acked-by: Jan Kara <jack@xxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -943,7 +943,7 @@ 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
Patches currently in stable-queue which might be from tj@xxxxxxxxxx are
queue-3.14/writeback-add-missing-initial_jiffies-init-in-global_update_bandwidth.patch
queue-3.14/writeback-fix-possible-underflow-in-write-bandwidth-calculation.patch
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