Re: [PATCH 3.17 00/25] 3.17.1-stable review

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Wed, Nov 19, 2014 at 12:16:48PM -0800, Greg Kroah-Hartman wrote:
> On Wed, Nov 19, 2014 at 11:44:14AM -0800, Paul E. McKenney wrote:
> > On Wed, Nov 19, 2014 at 09:22:35AM -0800, Greg Kroah-Hartman wrote:
> > > On Mon, Oct 13, 2014 at 08:23:19AM -0500, Chuck Ebbert wrote:
> > > > On Mon, 13 Oct 2014 08:28:35 -0300
> > > > Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:
> > > > 
> > > > > On Mon, 13 Oct 2014, Greg Kroah-Hartman wrote:
> > > > > > This is the start of the stable review cycle for the 3.17.1
> > > > > > release. There are 25 patches in this series, all will be posted
> > > > > > as a response to this one.  If anyone has any issues with these
> > > > > > being applied, please let me know.
> > > > > 
> > > > > Actually, 3.17 is a filesystem killer for some unlucky users due to
> > > > > the libata blacklist being disabled by a bug.
> > > > > 
> > > > > Patch:
> > > > > https://git.kernel.org/cgit/linux/kernel/git/tj/libata.git/patch/?id=1c40279960bcd7d52dbdf1d466b20d24b99176c8
> > > > > 1c40279960bcd7d52dbdf1d466b20d24b99176c8 (libata: Un-break ATA
> > > > > blacklist)
> > > > > 
> > > > 
> > > > There are some more bugs too:
> > > > 
> > > > 
> > > > RCU stalls, fix has been in rcu/urgent for 7 days:
> > > > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=rcu/urgent&id=789cbbeca4eb7141cbd748ee93772471101b507b
> > > 
> > > Doesn't build in 3.17 properly :(
> > > 
> > > > blk-mq bio merging (still no good fix available):
> > > > https://lkml.org/lkml/2014/10/9/729
> > > > (The fix sitting in the block tree:
> > > > https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-3.18/core&id=764f612c6c3c231b9c12cfae7c328ccc9c453258
> > > > is wrong according to that message.)
> > > 
> > > Did this ever get resolved?
> > > 
> > > > Stalls when using nohz, requires series of six patches to fix that
> > > > didn't make 3.17 and weren't marked for -stable:
> > > > 
> > > > From a80e49e2cc3145af014a8ae44f575829cc236192 Mon Sep 17 00:00:00 2001
> > > > From: Frederic Weisbecker <fweisbec@gmail.com>
> > > > Subject: nohz: Move nohz full init call to tick init
> > > > 
> > > > From c5c38ef3d70377dc504a6a3f611a3ec814bc757b Mon Sep 17 00:00:00 2001
> > > > From: Peter Zijlstra <peterz@infradead.org>
> > > > Subject: irq_work: Introduce arch_irq_work_has_interrupt()
> > > > 
> > > > From 76a33061b9323b7fdb220ae5fa116c10833ec22e Mon Sep 17 00:00:00 2001
> > > > From: Frederic Weisbecker <fweisbec@gmail.com>
> > > > Subject: irq_work: Force raised irq work to run on irq work interrupt
> > > > 
> > > > From 3010279f0fc36f0388872203e63ca49912f648fd Mon Sep 17 00:00:00 2001
> > > > From: Frederic Weisbecker <fweisbec@gmail.com>
> > > > Subject: x86: Tell irq work about self IPI support
> > > > 
> > > > From 09f6edd424218eb69078551b2ecfada1f2d098eb Mon Sep 17 00:00:00 2001
> > > > From: Frederic Weisbecker <fweisbec@gmail.com>
> > > > Subject: arm: Tell irq work about self IPI support
> > > > 
> > > > From 3631073659d0aafeaa52227bb61a100efaf901dc Mon Sep 17 00:00:00 2001
> > > > From: Frederic Weisbecker <fweisbec@gmail.com>
> > > To: 09f6edd424218eb69078551b2ecfada1f2d098eb
> > > To: Chuck Ebbert <cebbert.lkml@gmail.com>
> > > Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
> > > 	linux-kernel@vger.kernel.org, stable@kernel.org
> > > Bcc: 
> > > Subject: Re: [PATCH 3.17 00/25] 3.17.1-stable review
> > > Reply-To: 
> > > In-Reply-To: <20141013082319.175d90bb@as>
> > > 
> > > On Mon, Oct 13, 2014 at 08:23:19AM -0500, Chuck Ebbert wrote:
> > > > On Mon, 13 Oct 2014 08:28:35 -0300
> > > > Henrique de Moraes Holschuh <hmh@hmh.eng.br> wrote:
> > > > 
> > > > > On Mon, 13 Oct 2014, Greg Kroah-Hartman wrote:
> > > > > > This is the start of the stable review cycle for the 3.17.1
> > > > > > release. There are 25 patches in this series, all will be posted
> > > > > > as a response to this one.  If anyone has any issues with these
> > > > > > being applied, please let me know.
> > > > > 
> > > > > Actually, 3.17 is a filesystem killer for some unlucky users due to
> > > > > the libata blacklist being disabled by a bug.
> > > > > 
> > > > > Patch:
> > > > > https://git.kernel.org/cgit/linux/kernel/git/tj/libata.git/patch/?id=1c40279960bcd7d52dbdf1d466b20d24b99176c8
> > > > > 1c40279960bcd7d52dbdf1d466b20d24b99176c8 (libata: Un-break ATA
> > > > > blacklist)
> > > > > 
> > > > 
> > > > There are some more bugs too:
> > > > 
> > > > 
> > > > RCU stalls, fix has been in rcu/urgent for 7 days:
> > > > https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=rcu/urgent&id=789cbbeca4eb7141cbd748ee93772471101b507b
> > > 
> > > Doesn't build in 3.17 properly :(
> > 
> > Older kernels can use rcu_note_context_switch() instead of
> > rcu_note_voluntary_context_switch(), which didn't show up until quite
> > recently.  Please note that rcu_note_context_switch() is quite a bit
> > more heavy-weight than is rcu_note_voluntary_context_switch(), but it
> > should be OK in this context.
> 
> "OK" as in "worth the overhead to fix the known bug"?  Or is this just
> not worth backporting to 3.17, 3.14, and 3.10 as no one really hits this
> issue there?

"OK" as in "the added overhead of rcu_note_context_switch() is likely
to be down in the noise in this case".  I must confess that I have no
idea whether or not people hit this issue in 3.17, 3.14, or 3.10.

							Thanx, Paul