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

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Date:   Wed, 07 Nov 2018 15:34:51 +0000
From:   Chris Wilson <chris@...is-wilson.co.uk>
To:     Andrew Morton <akpm@...ux-foundation.org>
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

Quoting Andrew Morton (2018-11-06 18:12:11)
> 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.

Applied both corrections.

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

Thank you, pushed to drm-intel, expected to arrive around 4.21.
-Chris