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From: Minchan Kim <minchan@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Will Deacon <will@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Matthew Wilcox <willy@infradead.org>,
	Mike Galbraith <umgwanakikbuti@gmail.com>,
	Nitin Gupta <ngupta@vflare.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Subject: Re: [PATCH v3 7/7] zram: Use local lock to protect per-CPU data
Date: Fri, 29 May 2020 13:57:40 -0700	[thread overview]
Message-ID: <20200529205740.GD86436@google.com> (raw)
In-Reply-To: <20200527201119.1692513-8-bigeasy@linutronix.de>

On Wed, May 27, 2020 at 10:11:19PM +0200, Sebastian Andrzej Siewior wrote:
> From: Mike Galbraith <umgwanakikbuti@gmail.com>
> 
> The zcomp driver uses per-CPU compression. The per-CPU data pointer is
> acquired with get_cpu_ptr() which implicitly disables preemption.
> It allocates memory inside the preempt disabled region which conflicts
> with the PREEMPT_RT semantics.
> 
> Replace the implicit preemption control with an explicit local lock.
> This allows RT kernels to substitute it with a real per CPU lock, which
> serializes the access but keeps the code section preemptible. On non RT
> kernels this maps to preempt_disable() as before, i.e. no functional
> change.
> 
> [bigeasy: Use local_lock(), description, drop reordering]
> 
> Cc: Minchan Kim <minchan@kernel.org>
> Cc: Nitin Gupta <ngupta@vflare.org>
> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
> Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Minchan Kim <minchan@kernel.org>

  reply	other threads:[~2020-05-29 20:57 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 20:11 [PATCH v3 0/7] Introduce local_lock() Sebastian Andrzej Siewior
2020-05-27 20:11 ` [PATCH v3 1/7] locking: " Sebastian Andrzej Siewior
2020-06-01  9:52   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-05-27 20:11 ` [PATCH v3 2/7] radix-tree: Use local_lock for protection Sebastian Andrzej Siewior
2020-06-01  9:52   ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-05-27 20:11 ` [PATCH v3 3/7] mm/swap: " Sebastian Andrzej Siewior
2020-06-01  9:52   ` [tip: locking/core] " tip-bot2 for Ingo Molnar
2020-05-27 20:11 ` [PATCH v3 4/7] squashfs: make use of local lock in multi_cpu decompressor Sebastian Andrzej Siewior
2020-06-01  9:52   ` [tip: locking/core] squashfs: Make " tip-bot2 for Julia Cartwright
2020-05-27 20:11 ` [PATCH v3 5/7] connector/cn_proc: Protect send_msg() with a local lock Sebastian Andrzej Siewior
2020-06-01  9:52   ` [tip: locking/core] " tip-bot2 for Mike Galbraith
2020-05-27 20:11 ` [PATCH v3 6/7] zram: Allocate struct zcomp_strm as per-CPU memory Sebastian Andrzej Siewior
2020-05-29 20:51   ` Minchan Kim
2020-06-01  9:52   ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-05-27 20:11 ` [PATCH v3 7/7] zram: Use local lock to protect per-CPU data Sebastian Andrzej Siewior
2020-05-29 20:57   ` Minchan Kim [this message]
2020-06-01  9:52   ` [tip: locking/core] " tip-bot2 for Mike Galbraith
2020-10-19  1:52   ` [PATCH v3 7/7] " Yu Zhao
2020-10-19  2:33     ` Hugh Dickins
2020-10-19  2:33       ` Hugh Dickins
2020-10-19  2:46     ` Mike Galbraith
2020-10-19  2:46       ` Mike Galbraith

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