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From: Christoph Hellwig <hch@lst.de>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Christoph Hellwig <hch@lst.de>,
	akpm@linux-foundation.org, joelaf@google.com,
	jszhang@marvell.com, joaodias@google.com, linux-mm@kvack.org,
	linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
	Andy Lutomirski <luto@amacapital.net>
Subject: Re: [PATCH 2/6] mm: mark all calls into the vmalloc subsystem as potentially sleeping
Date: Wed, 19 Oct 2016 15:05:52 +0200	[thread overview]
Message-ID: <20161019130552.GB5876@lst.de> (raw)
In-Reply-To: <20161019111541.GQ29358@nuc-i3427.alporthouse.com>

On Wed, Oct 19, 2016 at 12:15:41PM +0100, Chris Wilson wrote:
> On Tue, Oct 18, 2016 at 08:56:07AM +0200, Christoph Hellwig wrote:
> > This is how everyone seems to already use them, but let's make that
> > explicit.
> 
> Ah, found an exception, vmapped stacks:

Oh, fun.  So if we can't require vfree to be called from process context
we also can't use a mutex to wait for the vmap flushing.  Given that we
free stacks from the scheduler context switch I also fear there is no
good way to get a sleepable context there.

The only other idea I had was to use vmap_area_lock for the protection
that purge_lock currently provides, but that would require some serious
refactoring to avoid recursive locking first.

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  reply	other threads:[~2016-10-19 13:05 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-18  6:56 [RFC] reduce latency in __purge_vmap_area_lazy Christoph Hellwig
2016-10-18  6:56 ` [PATCH 1/6] mm: refactor __purge_vmap_area_lazy Christoph Hellwig
2016-10-18  6:56 ` [PATCH 2/6] mm: mark all calls into the vmalloc subsystem as potentially sleeping Christoph Hellwig
2016-10-18 10:33   ` Chris Wilson
2016-10-18 10:38     ` Christoph Hellwig
2016-10-19 11:15   ` Chris Wilson
2016-10-19 13:05     ` Christoph Hellwig [this message]
2016-10-19 15:34       ` Andy Lutomirski
2016-10-19 16:31         ` Christoph Hellwig
2016-10-19 19:43           ` Chris Wilson
2016-10-21  0:32           ` Joel Fernandes
2016-11-08 13:24     ` Joel Fernandes
2016-11-08 14:32       ` Andrey Ryabinin
2016-10-18  6:56 ` [PATCH 3/6] mm: remove free_unmap_vmap_area_noflush Christoph Hellwig
2016-10-18  6:56 ` [PATCH 4/6] mm: remove free_unmap_vmap_area_addr Christoph Hellwig
2016-10-21  0:46   ` Joel Fernandes
2016-10-21  1:58     ` Nicholas Piggin
2016-10-18  6:56 ` [PATCH 5/6] mm: turn vmap_purge_lock into a mutex Christoph Hellwig
2016-10-18  6:56 ` [PATCH 6/6] mm: add preempt points into __purge_vmap_area_lazy Christoph Hellwig
2016-10-18 20:56   ` Steven Rostedt
2016-10-18 21:01     ` Steven Rostedt
2016-10-18 10:40 ` [RFC] reduce latency in __purge_vmap_area_lazy Nicholas Piggin
2016-10-18 11:21 ` Jisheng Zhang
2016-10-21  1:08 ` Joel Fernandes

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