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Fri, 27 Feb 2026 00:21:50 -0800 (PST) Received: from tigerii.tok.corp.google.com ([2a00:79e0:2031:6:280f:e47e:6718:7698]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2adfb69fa4fsm48796025ad.45.2026.02.27.00.21.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Feb 2026 00:21:49 -0800 (PST) From: Sergey Senozhatsky To: Andrew Morton , Minchan Kim Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-mm@kvack.org, Brian Geffon , Sergey Senozhatsky Subject: [PATCH 3/5] zram: recompression priority param should override algo Date: Fri, 27 Feb 2026 17:21:09 +0900 Message-ID: <831636c74ca6d72317de02d96585cc6833d082e6.1772180459.git.senozhatsky@chromium.org> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog In-Reply-To: <8a5d53d19a8dbd51d7d81d153676895163e0735e.1772180459.git.senozhatsky@chromium.org> References: <8a5d53d19a8dbd51d7d81d153676895163e0735e.1772180459.git.senozhatsky@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 172FC160006 X-Stat-Signature: 4yh93imfnan3ddyrrqqbaxf1c41p5wsy X-Rspam-User: X-HE-Tag: 1772180510-716323 X-HE-Meta: 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 Nk7bch76 nI9dNFqB/lSfMrj2mBV8TAxnUSJIQZ9useLDefRIpEIXG1TJVjbwpk1lPPsdPwFZfHxdJclUS2Bv8fD6Mt97qv6D0Q9kI1J2T47r/Ylo/l1SZNC1t0NgRw1g9y6Q4zEkfXQfNxjIz02np0DRxbjes+3I7+1M5k+bx+oPv6RSRhDqQDoAqIAUhCDvFEY605pI8QflWcfu9M9drvU9+vAX/XnCLkhheI9a9Fdhtjla2496GBGesDOBjs7qT5pAyKAP5yDRC8KHj3q9M/qAOAlNpp20A1PllyKYa9LNde7Mb2/ig+iv8F+aTb2Xl4TEKm5M64YwRSimwvtx/gM0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Recompression algorithm lookup by name is ambiguous and can lead to unexpected results. The problem is that the system can configure the same algorithm but with different parameters (compression level, C/D-dicts, etc.) multiple times: [zstd clevel=3] [zstd clevel=8 dict=/etc/dict] making it impossible to distinguish compressors by name. It is advised to always use "priority". Additionally, override "algo" with "priority", when both params are provided. Suggested-by: Minchan Kim Signed-off-by: Sergey Senozhatsky --- drivers/block/zram/zram_drv.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 6ca5a76c3865..118b0b277e37 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -2594,6 +2594,16 @@ static ssize_t recompress_store(struct device *dev, if (ret) return ret; + /* + * "priority" overrides "algo". + * + * We can have several algorithms configured with + * different params (compression/acceleration level, + * C/D-dict, etc.) but under the same name. + * + * "algorithm" name lookup is ambiguous. + */ + algo = NULL; prio_max = min(prio + 1, ZRAM_MAX_COMPS); continue; } -- 2.53.0.473.g4a7958ca14-goog