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Date: Mon, 14 Oct 2024 16:25:41 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Wei Xu <weixugc@google.com>
Cc: Yu Zhao <yuzhao@google.com>, Axel Rasmussen <axelrasmussen@google.com>,
 linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm/mglru: only clear kswapd_failures if reclaimable
Message-Id: <20241014162541.a3049d0824a2f9b22221c17a@linux-foundation.org>
In-Reply-To: <20241014221211.832591-1-weixugc@google.com>
References: <20241014221211.832591-1-weixugc@google.com>
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On Mon, 14 Oct 2024 22:12:11 +0000 Wei Xu <weixugc@google.com> wrote:

> lru_gen_shrink_node() unconditionally clears kswapd_failures, which
> can prevent kswapd from sleeping and cause 100% kswapd cpu usage even
> when kswapd repeatedly fails to make progress in reclaim.
> 
> Only clear kswap_failures in lru_gen_shrink_node() if reclaim makes
> some progress, similar to shrink_node().

That sounds bad.  What triggers this?  Can you suggest why it has just
bee discovered, after 1.5 years?  And should the fix be backported into
-stable kernels?