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Wed, 5 Nov 2025 08:46:58 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id UlxlNAIPC2lAcQAAD6G6ig (envelope-from ); Wed, 05 Nov 2025 08:46:58 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 8E5FCA28C2; Wed, 5 Nov 2025 09:46:58 +0100 (CET) Date: Wed, 5 Nov 2025 09:46:58 +0100 From: Jan Kara To: libaokun@huaweicloud.com Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, linux-kernel@vger.kernel.org, kernel@pankajraghav.com, mcgrof@kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, yi.zhang@huawei.com, yangerkun@huawei.com, chengzhihao1@huawei.com, libaokun1@huawei.com Subject: Re: [PATCH 11/25] ext4: support large block size in ext4_mb_load_buddy_gfp() Message-ID: References: <20251025032221.2905818-1-libaokun@huaweicloud.com> <20251025032221.2905818-12-libaokun@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20251025032221.2905818-12-libaokun@huaweicloud.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: B398220005 X-Stat-Signature: y8ku3km6gyj56o3ap6wt6h7f9g9byiuk X-Rspam-User: X-HE-Tag: 1762332420-373583 X-HE-Meta: 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 jPXq5xnQ b2k6Pzss2d/llLXYN1TSAFGwaltz6PNYZ0IgmCtMF7IPAkOsJO2RnIgGqmfSR1tMgTqeoABeEUoPaf32tUmRMIen6wXsphjTd/cWPJvwlQB9asCVDFJ0kAp/HPSwvB1hcsEtJRq9NBAb1W03vbLw62uPJslZWahmNuIPizURA68eL68nbDp8ZWM7zavGfHlGjrgmjDEVfZhcFjDd4sdgJsNc1dBS3Z0/4RVCPkXXyjgIOkU6ohJW44BbNZpz3ifTpdisOC4a1iD30ByqI1pP7u9VW3yg2ptu0jzL7JAvi/deng4MiIW9+d+ns/2DhzE+AKqk30LV2NbVOuVsZJiHiUzxmspvVoYsHxQy9H6PiJU8HHTfHgtBRGsMeTtbAnSXWa8bN2FI5xz9EKFjHvLCNNJjTLJKu2uagZspHwJiT/X8sIDAI+u75VOQsLEtsaSB6TygB/uDGH8Z6YSs= 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: List-Subscribe: List-Unsubscribe: On Sat 25-10-25 11:22:07, libaokun@huaweicloud.com wrote: > From: Baokun Li > > Currently, ext4_mb_load_buddy_gfp() uses blocks_per_page to calculate the > folio index and offset. However, when blocksize is larger than PAGE_SIZE, > blocks_per_page becomes zero, leading to a potential division-by-zero bug. > > To support BS > PS, use bytes to compute folio index and offset within > folio to get rid of blocks_per_page. > > Also, if buddy and bitmap land in the same folio, we get that folio’s ref > instead of looking it up again before updating the buddy. > > Signed-off-by: Baokun Li > Reviewed-by: Zhang Yi Looks good! Feel free to add: Reviewed-by: Jan Kara Honza -- Jan Kara SUSE Labs, CR