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Tue, 25 Jul 2023 19:31:28 -0700 (PDT) Received: from google.com ([2401:fa00:8f:203:a2a4:d590:6375:66ba]) by smtp.gmail.com with ESMTPSA id u11-20020aa7848b000000b00686bfbb7353sm325907pfn.184.2023.07.25.19.31.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Jul 2023 19:31:27 -0700 (PDT) Date: Wed, 26 Jul 2023 11:31:22 +0900 From: Sergey Senozhatsky To: Andrew Yang Cc: Minchan Kim , Sergey Senozhatsky , Andrew Morton , Matthias Brugger , AngeloGioacchino Del Regno , Sebastian Andrzej Siewior , wsd_upstream@mediatek.com, casper.li@mediatek.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH] zsmalloc: Fix races between modifications of fullness and isolated Message-ID: <20230726023122.GH955071@google.com> References: <20230721063705.11455-1-andrew.yang@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230721063705.11455-1-andrew.yang@mediatek.com> X-Rspamd-Queue-Id: 0C0B51C000D X-Rspam-User: X-Stat-Signature: wwxmy55wptwxwnzgip9m5kg8x1bh5hf5 X-Rspamd-Server: rspam03 X-HE-Tag: 1690338689-319644 X-HE-Meta: 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 kpIBCXvT dOFWMT4lrulc61cJvIwqXtCXHVEcEW8nhRDJCT0ZwKEkIr0F+sqq3kDckZ8KwY4SQv0yeFf6h/3LRYxm+qLgbY/MTn5VmZOJ+iXPs2Ccwt9wzbz8vA8E77CasnYlalTlrlMJBp+HytGu7nGPykrdG+680TMShZzdpiiuP45it0wvlsNqiIm5cuj8QnIa3aVxwwL4dr8RtTldCCvAO9MLVYDeaCA+DO5FGd/5pcsmrChBsxTnIuGhA088XsN9nRGZAWgXopObG1T6nUQ6B4C3vSdaLyor7WwAWHguZdiKUy1Q/A3jUe16IGZ1NgR5G83QhssGOJj5jOHCr0TpnEZOx0PKFGjAkiiWik51wnfk7L4yAN8ibxmiKuuQLNUBNTIAcwTOTj4yQq0KwZE3tkbJ1Xoml14u/uEtVqNH0g6ePX4uXncw= X-Bogosity: Ham, tests=bogofilter, spamicity=0.009586, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On (23/07/21 14:37), Andrew Yang wrote: > > Since fullness and isolated share the same unsigned int, > modifications of them should be protected by the same lock. Sorry, I don't think I follow. Can you please elaborate? What is fullness in this context? What is the race condition exactly? Can I please have something like CPU0 CPU1 foo bar