+ zram-do-not-release-zstd-global-params-from-error-paths.patch added to mm-new branch

+ zram-do-not-release-zstd-global-params-from-error-paths.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: zram: do not release zstd global params from error paths
has been added to the -mm mm-new branch.  Its filename is
     zram-do-not-release-zstd-global-params-from-error-paths.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-do-not-release-zstd-global-params-from-error-paths.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.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Haoqin Huang <haoqinhuang@tencent.com>
Subject: zram: do not release zstd global params from error paths
Date: Tue, 4 Aug 2026 17:38:37 +0800

Patch series "zram: fix zstd error paths and add parameter validation", v6,

Patch 1 removes zstd_release_params() from both zstd_create() and
zstd_setup_params() error paths -- the former is a layering violation
in a per-CPU callback, the latter is redundant as zcomp_init() already
calls release_params() on setup failure.

Patch 2 rejects zero-size dictionaries and prints distinct error
messages for sz < 0 (returns the original error code) and sz == 0
("empty file"). Currently errors are silently swallowed.

Patch 3 adds pr_fmt to each backend file so that pr_err() messages
are auto-prefixed with the algorithm name.

Patch 4 validates dict and level parameters in each backend's
.setup_params(), rejecting unsupported combinations and out-of-range
levels.

Patch 5 resets per-priority params on algorithm change before init.


This patch (of 5):

zstd_setup_params() creates global cdict and ddict stored in
params->drv_data, shared across all per-CPU contexts.  The per-CPU
zstd_create() error path called zstd_release_params(), which freed those
globally-shared objects.  This is a layering violation: a per-CPU callback
should only clean up its own context, not release resources owned by the
compression lifecycle.

zstd_setup_params() called zstd_release_params() on its own error path as
well, but zcomp_init() already calls release_params() when setup fails, so
this is redundant.

Remove zstd_release_params() from both error paths.

Link: https://lore.kernel.org/20260804093841.67920-1-haoqinhuang7@gmail.com
Link: https://lore.kernel.org/20260804093841.67920-2-haoqinhuang7@gmail.com
Signed-off-by: Haoqin Huang <haoqinhuang@tencent.com>
Signed-off-by: Rongwei Wang <zigiwang@tencent.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/backend_zstd.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/block/zram/backend_zstd.c~zram-do-not-release-zstd-global-params-from-error-paths
+++ a/drivers/block/zram/backend_zstd.c
@@ -85,7 +85,6 @@ static int zstd_setup_params(struct zcom
 	return 0;
 
 error:
-	zstd_release_params(params);
 	return -EINVAL;
 }
 
@@ -161,7 +160,6 @@ static int zstd_create(struct zcomp_para
 	return 0;
 
 error:
-	zstd_release_params(params);
 	zstd_destroy(ctx);
 	return -EINVAL;
 }
_

Patches currently in -mm which might be from haoqinhuang@tencent.com are

zram-do-not-release-zstd-global-params-from-error-paths.patch
zram-reject-zero-size-dictionary.patch
zram-add-pr_fmt-to-backend-files.patch
zram-validate-parameters-in-each-backends-setup_params.patch
zram-reset-per-priority-params-when-changing-algorithm-before-init.patch