From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>,
LKML <linux-kernel@vger.kernel.org>,
linux-rt-users <linux-rt-users@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch-rt] drivers/zram: fix zcomp_stream_get() smp_processor_id() use in preemptible code
Date: Fri, 1 Sep 2017 09:40:23 +0200 [thread overview]
Message-ID: <20170901074023.2ctuzw3ohlnlmtid@linutronix.de> (raw)
In-Reply-To: <alpine.DEB.2.20.1708312130260.2346@nanos>
On 2017-08-31 21:32:30 [+0200], Thomas Gleixner wrote:
> > zram_lock_table() is bit_spin_lock() on !RT and spin_lock(&table->lock);
> > on RT. So this is done.
> > !RT has this running in a kmap_atomic() section so they have no
> > preemption there.
> > zcomp_stream_get() returns a per-CPU object which is protected with a
> > spinlock and only accessed locked.
>
> So when we are inside a spinlocked section, why is this_cpu_ptr() not
> working? That does not make sense.
zram_decompress_page() invokes zcomp_stream_get() within a spin_lock
section (zram_lock_table()). This is fine.
zram_bvec_write() does not invoke zcomp_stream_get() within a spin_lock
section.
> Thanks,
>
> tglx
Sebastian
next prev parent reply other threads:[~2017-09-01 7:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-18 12:09 [ANNOUNCE] v4.11.12-rt10 Sebastian Andrzej Siewior
2017-08-23 9:53 ` v4.11.12-rt10 - hotplug lockdep splat Mike Galbraith
2017-08-31 16:18 ` Sebastian Andrzej Siewior
2017-09-02 7:00 ` Mike Galbraith
2017-09-03 2:48 ` Mike Galbraith
2017-09-04 14:58 ` Sebastian Andrzej Siewior
2017-08-23 9:57 ` [patch-rt] drivers/zram: fix zcomp_stream_get() smp_processor_id() use in preemptible code Mike Galbraith
2017-08-31 15:48 ` Sebastian Andrzej Siewior
2017-08-31 19:11 ` Thomas Gleixner
2017-08-31 19:26 ` Sebastian Andrzej Siewior
2017-08-31 19:32 ` Thomas Gleixner
2017-09-01 7:40 ` Sebastian Andrzej Siewior [this message]
2017-09-01 7:47 ` Thomas Gleixner
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