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bh=tJAJOI4zNpAbAbSJ2yiWr+f0FAyzO0/dqLTfBJ1SAuM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=YZ6MVO3RRUTR+rziKBAQ2Slq8Tjj2nwPpk/s6NbJ25w8iAiaFw9c8aDVrmXDscW8Q ic0xEnsKEGMniLygHDocWC0YQtdfkMLVkJ2JquZUY4SCkkHYMbfR0hjIUSbmIled2o xxMKQ+QHowfWK2eJAk8cLimZAvft7Mf7r8XwNt7U= Date: Wed, 19 Apr 2023 12:49:02 -0700 From: Andrew Morton To: Peng Zhang Cc: Liam.Howlett@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org Subject: Re: [PATCH] maple_tree: Fix allocation in mas_sparse_area() Message-Id: <20230419124902.7cb9b5c54afa37736e7b0e3a@linux-foundation.org> In-Reply-To: <20230419093625.99201-1-zhangpeng.00@bytedance.com> References: <20230419093625.99201-1-zhangpeng.00@bytedance.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: BD00E40008 X-Rspam-User: X-Stat-Signature: siw1ymq6q1r8qny3mwnaqmp5kbexyufw X-HE-Tag: 1681933744-422434 X-HE-Meta: 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 quBAHHbv go3lNo6dXQLko63wBMoo6mvWhHcUDwLHCCDBdQZt63IJC3At87z9Eb3qeQ7l+Ti9eq3zRlSIo1S0HkZ02H1pm76b9OMCM5ZZEk3PglOHMNH2dS27jM6xfJzdY0UwSkZY0Oa3GDItkvrSIoASXyt+gGuogniDnVPMwoIsvIxeapn0+o4588YucoGWSJeJ+0IbPKdkz+/IYwvWQDOZtw/O9NukE/SXEMAsC86faa2ghC+u/ikepK1wlm7vSMV/yde0KRMJbVB5zqP9RH99Hujvfu69ziEYVyRimD223ct6DfMESomscZf88Xefnfy+MCGpD8J7xFwLSl0pIpUqFv+xnhVk2eI4TwyiZcpwgWbEPkAgtpZ6iG5T7FwaFj/XvCgPWJw2aqp4u07VuBQW8+SGHEQk+eYHwAZ+kDlRTFDHZAG0NnggUCSXW+ATUAOGMuJPG55xL 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: On Wed, 19 Apr 2023 17:36:25 +0800 Peng Zhang wrote: > In the case of reverse allocation, mas->index and mas->last do not point > to the correct allocation range, which will cause users to get incorrect > allocation results, so fix it. If the user does not use it in a specific > way, this bug will not be triggered. Please describe the user-visible effects of the bug. I assume "none", because there are presently no callers which can trigger it? > Also re-checks whether the size is still satisfied after the lower bound > was increased, which is a corner case and is incorrect in previous versions. Again, what are the user-visible effects of the bug?