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[124.209.188.1]) by smtp.gmail.com with ESMTPSA id w7-20020a170902904700b001a25d7d1fbcsm7594893plz.38.2023.04.17.05.37.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Apr 2023 05:37:43 -0700 (PDT) Date: Mon, 17 Apr 2023 21:37:40 +0900 From: Sergey Senozhatsky To: Yosry Ahmed Cc: Sergey Senozhatsky , Minchan Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] zsmalloc: allow only one active pool compaction context Message-ID: <20230417123740.GP25053@google.com> References: <20230417110259.1737315-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 3055814000D X-Rspam-User: X-Stat-Signature: cdwekaxbb4wx77qqyfzjukrigsoyr8g5 X-HE-Tag: 1681735064-588947 X-HE-Meta: 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 ji2WXWC6 lcti9ud8uViu+x46RoxiCVwj1sqJpZYz+7MWq4PQHr+FOLjSKHHIeoLnOisRFrL6CwF+AFNgVufakm7nE5BvTtIMUcgqpNns0MKSHbHjZ38UDXuVDZsTOL4kct+QwpHi6c5Gqsb2trkA2XT+fp4nyBTPJnPdoVqmKD5Vypi5BhN7BwoX4njf3a7t8l5yLIvUb+Cl5r+spr9+a4w/MF+B/TPu2MIsK16tbOZ0LNeJWrjBrcUP1+1ZzGf4qSJ2HAfUUdmepNh91ZFYBG42lTUqK8vXtYquLSbRpVxF1JasXWWw3TlIiDjEMZ2ERTLF5pZLQhItxowIWDtjhjrswCICaAJrduhp/zLAotDKiD7iUdo+s0KPgV0PxoLiq3A== 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: Hi, On (23/04/17 04:53), Yosry Ahmed wrote: > > Introduce pool compaction mutex and permit only one compaction > > context at a time. > > I am not sure what's the best practice here, but if the only use of > the mutex is a trylock, do we need a mutex here? It seems like a > simple atomic would do the trick. Perhaps something like: > > static atomic_t ongoing_compaction = ATOMIC_INIT(0); > ... > if (atomic_xchg(&ongoing_compaction, 1)) > return; > .... > atomic_set(&ongoing_compaction, 0); Looks good to me. Will switch to atomic_t in v2.