linux-kernel - Re: [PATCH v7] mm, drm/i915: mark pinned shmemfs pages as unevictable

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Message-Id: <20181106101211.d2e4857aa36ea8ffbd870d2f@linux-foundation.org>
Date:   Tue, 6 Nov 2018 10:12:11 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     intel-gfx@...ts.freedesktop.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Kuo-Hsin Yang <vovoy@...omium.org>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH v7] mm, drm/i915: mark pinned shmemfs pages as
 unevictable

On Tue,  6 Nov 2018 13:23:24 +0000 Chris Wilson <chris@...is-wilson.co.uk> wrote:

> From: Kuo-Hsin Yang <vovoy@...omium.org>
> 
> The i915 driver uses shmemfs to allocate backing storage for gem
> objects. These shmemfs pages can be pinned (increased ref count) by
> shmem_read_mapping_page_gfp(). When a lot of pages are pinned, vmscan
> wastes a lot of time scanning these pinned pages. In some extreme case,
> all pages in the inactive anon lru are pinned, and only the inactive
> anon lru is scanned due to inactive_ratio, the system cannot swap and
> invokes the oom-killer. Mark these pinned pages as unevictable to speed
> up vmscan.
> 
> Export pagevec API check_move_unevictable_pages().
> 
> This patch was inspired by Chris Wilson's change [1].
> 
> [1]: https://patchwork.kernel.org/patch/9768741/
> 
> ...
>
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2382,12 +2382,26 @@ void __i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
>  	invalidate_mapping_pages(mapping, 0, (loff_t)-1);
>  }
>  
> +/**

This token is used to introduce a kerneldoc comment.

> + * Move pages to appropriate lru and release the pagevec. Decrement the ref
> + * count of these pages.
> + */

But this isn't a kerneldoc comment.

At least, I don't think it is.  Maybe the parser got smarter when I
wasn't looking.

> +static inline void check_release_pagevec(struct pagevec *pvec)
> +{
> +	if (pagevec_count(pvec)) {
> +		check_move_unevictable_pages(pvec);
> +		__pagevec_release(pvec);
> +		cond_resched();
> +	}
> +}

This looks too large to be inlined and the compiler will ignore the
`inline' anyway.


Otherwise, Acked-by: Andrew Morton <akpm@...ux-foundation.org>.  Please
go ahead and merge via the appropriate drm tree.