+ zram-recompression-priority-param-should-override-algo.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

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The patch titled
     Subject: zram: recompression priority param should override algo
has been added to the -mm mm-new branch.  Its filename is
     zram-recompression-priority-param-should-override-algo.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-recompression-priority-param-should-override-algo.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
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fixup patches in mm-new.

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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: zram: recompression priority param should override algo
Date: Fri, 27 Feb 2026 17:21:09 +0900

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.

Link: https://lkml.kernel.org/r/831636c74ca6d72317de02d96585cc6833d082e6.1772180459.git.senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Suggested-by: Minchan Kim <minchan@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: "Christoph Böhmwalder" <christoph.boehmwalder@linbit.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/block/zram/zram_drv.c~zram-recompression-priority-param-should-override-algo
+++ a/drivers/block/zram/zram_drv.c
@@ -2594,6 +2594,16 @@ static ssize_t recompress_store(struct d
 			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;
 		}
_

Patches currently in -mm which might be from senozhatsky@chromium.org are

zram-rename-writeback_compressed-device-attr.patch
zram-do-not-autocorrect-bad-recompression-parameters.patch
zram-drop-num_active_comps.patch
zram-recompression-priority-param-should-override-algo.patch
zram-update-recompression-documentation.patch
zram-remove-chained-recompression.patch