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[2603:7000:c01:2716:97cf:7b55:44af:acd6]) by smtp.gmail.com with ESMTPSA id t23-20020a6b0917000000b007bfea3c536esm23386ioi.28.2024.02.01.09.45.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Feb 2024 09:45:48 -0800 (PST) Date: Thu, 1 Feb 2024 12:45:47 -0500 From: Johannes Weiner To: Chengming Zhou Cc: Nhat Pham , Andrew Morton , Yosry Ahmed , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/6] mm/zswap: add more comments in shrink_memcg_cb() Message-ID: <20240201174547.GA321148@cmpxchg.org> References: <20240201-b4-zswap-invalidate-entry-v1-0-56ed496b6e55@bytedance.com> <20240201-b4-zswap-invalidate-entry-v1-1-56ed496b6e55@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240201-b4-zswap-invalidate-entry-v1-1-56ed496b6e55@bytedance.com> X-Rspamd-Queue-Id: 30C9740016 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: u1of7ag7cb5imj5xn59cjg6krtgtsp9y X-HE-Tag: 1706809549-988164 X-HE-Meta: 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 PpLB1g5Q 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 Thu, Feb 01, 2024 at 03:49:01PM +0000, Chengming Zhou wrote: > Add more comments in shrink_memcg_cb() to describe the deref dance > which is implemented to fix race problem between lru writeback and > swapoff, and the reason why we rotate the entry at the beginning. > > Also fix the stale comments in zswap_writeback_entry(), and add > more comments to state that we only deref the tree after we get > the swapcache reference. > > Suggested-by: Yosry Ahmed > Suggested-by: Johannes Weiner > Signed-off-by: Chengming Zhou Signed-off-by: Johannes Weiner Thanks!