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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	intel-gfx@lists.freedesktop.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/2] mm/mmu_notifier: Mark up direct reclaim paths with MAYFAIL
Date: Wed, 24 Jun 2020 09:10:53 -0300	[thread overview]
Message-ID: <20200624121053.GD6578@ziepe.ca> (raw)
In-Reply-To: <20200624080248.3701-1-chris@chris-wilson.co.uk>

On Wed, Jun 24, 2020 at 09:02:47AM +0100, Chris Wilson wrote:
> When direct reclaim enters the shrinker and tries to reclaim pages, it
> has to opportunitically unmap them [try_to_unmap_one]. For direct
> reclaim, the calling context is unknown and may include attempts to
> unmap one page of a dma object while attempting to allocate more pages
> for that object. Pass the information along that we are inside an
> opportunistic unmap that can allow that page to remain referenced and
> mapped, and let the callback opt in to avoiding a recursive wait.

i915 should already not be holding locks shared with the notifiers
across allocations that can trigger reclaim. This is already required
to use notifiers correctly anyhow - why do we need something in the
notifiers?

I really don't like this patch, the purpose of notifiers is only to
*track changes* not to influence policy of the callers.

Jason

  parent reply	other threads:[~2020-06-24 12:10 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24  8:02 [PATCH 1/2] mm/mmu_notifier: Mark up direct reclaim paths with MAYFAIL Chris Wilson
2020-06-24  8:02 ` [PATCH 2/2] drm/i915/gem: Use mmu_notifier_range_mayfail() to avoid waiting inside reclaim Chris Wilson
2020-06-24 12:10 ` Jason Gunthorpe [this message]
2020-06-24 12:21   ` [PATCH 1/2] mm/mmu_notifier: Mark up direct reclaim paths with MAYFAIL Chris Wilson
2020-06-24 12:39     ` Jason Gunthorpe
2020-06-24 14:12       ` Chris Wilson
2020-06-24 14:16         ` Jason Gunthorpe
2020-06-24 14:21           ` Chris Wilson
2020-06-24 14:25             ` Jason Gunthorpe
2020-06-24 14:37               ` Chris Wilson
2020-06-24 16:50                 ` Jason Gunthorpe
2020-06-24 17:58                   ` Chris Wilson
2020-06-24 18:48                     ` Jason Gunthorpe

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