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Thu, 03 Sep 2026 09:17:12 +0000 X-Mizu-Trace-ID: 2edda1273ec6a1c8 X-Migadu-Flow: FLOW_OUT Date: Thu, 3 Sep 2026 17:17:00 +0800 From: Baoquan He To: Nhat Pham Cc: Baoquan He , linux-mm@kvack.org, akpm@linux-foundation.org, chrisl@kernel.org, kasong@tencent.com, baohua@kernel.org, youngjun.park@lge.com, hannes@cmpxchg.org, yosry@kernel.org, shikemeng@huaweicloud.com, chengming.zhou@linux.dev, david@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/16] mm, swap: defer xswap shrink to workqueue to avoid lock recursion Message-ID: References: <20260827094509.1016740-1-hebaoquan@kylinos.cn> <20260827094509.1016740-14-hebaoquan@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D7EF2160003 X-Stat-Signature: zkn8k4dwnt6zcz5e9bb68ag5mpcjr8u8 X-HE-Tag: 1788427033-886647 X-HE-Meta: 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 e5mEKiIR 9iuul4T/sGIK6MbZucH6Fd7kZhfBQyll7JyjZuUvQEvnf921cyHUp+w4BWeUVC3kgKOS3rwIkMAGsO3Nze79zicUZ1Bbku9FPW39STFHa3c0UIYG+qDtU1a/OCoh6Q4oHiNbb984B3W3YpiNb+tfeSIkzmWEs9qGsGKzpAB/TvmLzad17WpWo+vJMg1UDSnMQkhyWE89mLAsy5ePeD9Q0WCgwHe/LH9v2Bp339L/jmHYAT10XgO2F6xwtCqvWO/purKFHXOwMosekSX95DfIl6bJL9gOSIiJLQUDcuOUO3YsLHNg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/02/26 at 10:50am, Nhat Pham wrote: > On Thu, Aug 27, 2026 at 5:57 AM Baoquan He wrote: > > > > xswap_try_shrink() was called directly from __free_cluster() while > > holding ci->lock. The shrink path calls xswap_unmap_clusters() > > which unmaps vmalloc pages backing cluster_info, and on return > > swap_cache_del_folio() tries swap_cluster_unlock(ci) on the now- > > unmapped address - crashing on a not-present page. > > This reads like a bug. It would be a bisectability problem to not > squash this to an earlier patch, no? I intentionally keep it as an independent patch. This is a new feature, we don't need to worry about bisectability problem. Mainly I want to the code change explained clearer, any people can get it from the git log. If I squash all them into one commit, it's very hard to let people know which paragraph describes what change, esp the commit is big. If it's a logic unit with a reason, I would separate it out as an independent patch. People review it and ack if no objection, then go to the next one. It's better than a big patch with which we reviewed one round, this place is changed, next round, the other place is changed. Then next round, a new place mixed the 1st place is changed. We sometime even don't know what is settled, what is not.