FAILED: patch "[PATCH] zram: set default primary compressor in zram_destroy_comps()" failed to apply to 6.12-stable tree

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x dde75313eed0b014c437f48dd75c0308b592cbf9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090323-reflux-devoutly-8bce@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From dde75313eed0b014c437f48dd75c0308b592cbf9 Mon Sep 17 00:00:00 2001
From: Sergey Senozhatsky <[email protected]>
Date: Wed, 29 Jul 2026 13:57:35 +0900
Subject: [PATCH] zram: set default primary compressor in zram_destroy_comps()

Patch series "zram: fix zram issues reported by sashiko".

Sashiko drove by and reported [1] a couple of zram issues:
a possible BUG_ON() in zlib code due to missing winbits range validation and one possible NULL-ptr dereference in zcomp. Both are low risk yet still worth fixing.

This patch (of 2):

zram_destroy_comps() resets all compressors and leaves them set to NULL, including the primary one, which is invalid device state, as now comp_algorithm_show()->strcmp() can be called on a NULL compressor. Set default primary compressor in zram_destroy_comps().

index 4bfe63a5225d..cfa98846ac48 100644
@@ -2828,6 +2828,7 @@ static void zram_destroy_comps(struct zram *zram)
 		zram->comp_algs[prio] = NULL;
 
 	zram_comp_params_reset(zram);
+	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
 }
 
 static void zram_reset_device(struct zram *zram)

@@ -2845,8 +2846,6 @@ static void zram_reset_device(struct zram *zram)
 	zram_destroy_comps(zram);
 	memset(&zram->stats, 0, sizeof(zram->stats));
 	reset_bdev(zram);
-
-	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
 }
 
 static ssize_t disksize_store(struct device *dev, struct device_attribute *attr,

From: Sergey Senozhatsky <[email protected]>

[ Upstream commit 0d38260c2a11de147f0c4701b344fdfa6bcdd04c ]

Use init_lock guard() in sysfs store/show handlers, in order to simplify and, more importantly, to modernize the code.

While at it, fix up more coding styles.

For the 6.12 stable backport, retain only the zram_reset_device() conversion needed by the follow-up fix. The remaining upstream hunks apply to zram paths that have significantly diverged in this tree.

Stable-dep-of: dde75313eed0 ("zram: set default primary compressor in zram_destroy_comps()")

---
 drivers/block/zram/zram_drv.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index cf3c789945b41..e11f0ff18012a 100644
@@ -2173,7 +2173,7 @@ static void zram_destroy_comps(struct zram *zram)
 
 static void zram_reset_device(struct zram *zram)
 {
-	down_write(&zram->init_lock);
+	guard(rwsem_write)(&zram->init_lock);
 
 	zram->limit_pages = 0;
 

@@ -2189,7 +2189,6 @@ static void zram_reset_device(struct zram *zram)
 	reset_bdev(zram);
 
 	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
-	up_write(&zram->init_lock);
 }
 
 static ssize_t disksize_store(struct device *dev,

2.53.0

From: Sergey Senozhatsky <[email protected]>

[ Upstream commit dde75313eed0b014c437f48dd75c0308b592cbf9 ]

Patch series "zram: fix zram issues reported by sashiko".

Sashiko drove by and reported [1] a couple of zram issues:
a possible BUG_ON() in zlib code due to missing winbits range validation and one possible NULL-ptr dereference in zcomp. Both are low risk yet still worth fixing.

This patch (of 2):

zram_destroy_comps() resets all compressors and leaves them set to NULL, including the primary one, which is invalid device state, as now comp_algorithm_show()->strcmp() can be called on a NULL compressor. Set default primary compressor in zram_destroy_comps().

---
 drivers/block/zram/zram_drv.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index e11f0ff18012a..c97e025b82b44 100644
@@ -2169,6 +2169,7 @@ static void zram_destroy_comps(struct zram *zram)
 	}
 
 	zram_comp_params_reset(zram);
+	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
 }
 
 static void zram_reset_device(struct zram *zram)

@@ -2187,8 +2188,6 @@ static void zram_reset_device(struct zram *zram)
 	memset(&zram->stats, 0, sizeof(zram->stats));
 	atomic_set(&zram->pp_in_progress, 0);
 	reset_bdev(zram);
-
-	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
 }
 
 static ssize_t disksize_store(struct device *dev,

2.53.0