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h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=puq9HXMRl5VMF9cVvtRHVU08G1XuO/JjTgHJrBbT+N3q2LWjoDvzRBX8uNu5WnZX+ GLYwI4z8wvLGlKFeRn8si4CiuF1JsF9ug8SRaGkBtnU4lS2DuRjk7DHfbqJcnVaE44 p001S+ueiRDyWIay86xzrmqS4O5s8nGVRoWt5lC8= Date: Mon, 14 Oct 2024 16:25:41 -0700 From: Andrew Morton To: Wei Xu Cc: Yu Zhao , Axel Rasmussen , 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> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: hbrn7zcbipra5hdrwgiqxxrkje9txtdg X-Rspamd-Queue-Id: 000EC1C0005 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1728948340-275423 X-HE-Meta: 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 B1E/JNf1 q+wEVivo+f45vnJ7D0coXqJMZAEwmiQOD4UsbSxbOpCCx4nhFeegt8SQPOYq5mCPEQQQHJ2/QLwBuQSnkyf3pBVzrRFyzmtFx1/fVC192WLHNC0H2l7/vr/uyXeo7SWpmOsCJ7mKqE0T1QsaYyno7JcIqGJqO9uGck0pmSZAwUYjHj9eIJSxPbwrLSLUsprOWiJz+y8EEY8FjGF71gO9jegvOzcGF/PKiJ3gY3YW71vQj9Rqd3AtqCjrevkH5RwDU80Os9/eBoujq3IrW+siP6MCQgwv2Q6yftg2QxcM6Sfavrt4eQhZ6o173V9g0Kn2f4el1 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 14 Oct 2024 22:12:11 +0000 Wei Xu 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?