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Tue, 25 Jul 2023 20:18:50 -0700 (PDT) Date: Wed, 26 Jul 2023 12:18:46 +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: <20230726031846.GJ955071@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-Rspam-User: X-Stat-Signature: df1um18rkw7fhi8aomuib8xzwambnowi X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 0F31710000A X-HE-Tag: 1690341531-206533 X-HE-Meta: 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 /TqmhEkG QAeMyUTEhbjn18EzdeiXvVkxx3+BAY55bt078jZCUi6VC06aP7ZK50zpxaHp6n0UfmsixK+UMmYm8ZQwgQaEszELSwSFTcYQrqpmt9eJqluXs3FTY3NFfDbUl8y6XMNigpEv6R5++rLfwLDiqghIggJfSVHkMZrjfj7fIJ6zBIb/PKpKZ4arQFJrjHMj5aMKL4kTKr75CvHibCMnCfw6WI+yg02sAAOEh4bqUo93Ol36WEObTY+4Z7N9XOge9mkPtaIVCid5pDhzW5+LYFKOxkwbsHIUWTHNvR8Ad3ToWdEyK49g1emMPNIDhSNFA3946o6m7Mvg48IPbjfGCZS53PlCSq6CuLsw9r1/wf5h8rhbMWex2ad2UKUthOdvN7KKjAHzMZK5zll+g/30cK7JIe2Mq4WLTP7oWa/96rnRIJQdTMWX/MqiTLz2mvFd/7lwKRiVjpnP4leaUGvU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.028461, 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. > > Signed-off-by: Andrew Yang > Fixes: c4549b871102 ("zsmalloc: remove zspage isolation for migration") Have you observed issues in real life? That commit is more than a year and a half old, so I wonder. > @@ -1858,8 +1860,8 @@ static int zs_page_migrate(struct page *newpage, struct page *page, > * Since we complete the data copy and set up new zspage structure, > * it's okay to release the pool's lock. > */ This comment should be moved too, because this is not where we unlock the pool anymore. > - spin_unlock(&pool->lock); > dec_zspage_isolation(zspage); > + spin_unlock(&pool->lock); > migrate_write_unlock(zspage);