Re: [PATCH v2 42/47] drm/ttm: introduce pool_shrink_rwsem

From: Muchun Song
Date: Wed Jul 26 2023 - 04:05:46 EST

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In reply to: Qi Zheng: "[PATCH v2 42/47] drm/ttm: introduce pool_shrink_rwsem"
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> On Jul 24, 2023, at 17:43, Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> wrote:
>
> Currently, the synchronize_shrinkers() is only used by TTM pool. It only
> requires that no shrinkers run in parallel.
>
> After we use RCU+refcount method to implement the lockless slab shrink,
> we can not use shrinker_rwsem or synchronize_rcu() to guarantee that all
> shrinker invocations have seen an update before freeing memory.
>
> So we introduce a new pool_shrink_rwsem to implement a private
> synchronize_shrinkers(), so as to achieve the same purpose.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>

Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>