+ zram-do-not-autocorrect-bad-recompression-parameters.patch added to mm-unstable branch

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

The patch titled
     Subject: zram: do not autocorrect bad recompression parameters
has been added to the -mm mm-unstable branch.  Its filename is
     zram-do-not-autocorrect-bad-recompression-parameters.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-autocorrect-bad-recompression-parameters.patch

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@chromium.org>
Subject: zram: do not autocorrect bad recompression parameters
Date: Wed, 11 Mar 2026 17:42:45 +0900

Do not silently autocorrect bad recompression priority parameter value and
just error out.

Link: https://lkml.kernel.org/r/20260311084312.1766036-3-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: gao xu <gaoxu2@honor.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zram-do-not-autocorrect-bad-recompression-parameters
+++ a/drivers/block/zram/zram_drv.c
@@ -2528,19 +2528,16 @@ static ssize_t recompress_store(struct d
 				struct device_attribute *attr,
 				const char *buf, size_t len)
 {
+	u32 prio = ZRAM_SECONDARY_COMP, prio_max = ZRAM_MAX_COMPS;
 	struct zram *zram = dev_to_zram(dev);
 	char *args, *param, *val, *algo = NULL;
 	u64 num_recomp_pages = ULLONG_MAX;
 	struct zram_pp_ctl *ctl = NULL;
 	struct zram_pp_slot *pps;
 	u32 mode = 0, threshold = 0;
-	u32 prio, prio_max;
 	struct page *page = NULL;
 	ssize_t ret;
 
-	prio = ZRAM_SECONDARY_COMP;
-	prio_max = zram->num_active_comps;
-
 	args = skip_spaces(buf);
 	while (*args) {
 		args = next_arg(args, &param, &val);
@@ -2590,10 +2587,7 @@ static ssize_t recompress_store(struct d
 			if (ret)
 				return ret;
 
-			if (prio == ZRAM_PRIMARY_COMP)
-				prio = ZRAM_SECONDARY_COMP;
-
-			prio_max = prio + 1;
+			prio_max = min(prio + 1, ZRAM_MAX_COMPS);
 			continue;
 		}
 	}
@@ -2613,7 +2607,7 @@ static ssize_t recompress_store(struct d
 				continue;
 
 			if (!strcmp(zram->comp_algs[prio], algo)) {
-				prio_max = prio + 1;
+				prio_max = min(prio + 1, ZRAM_MAX_COMPS);
 				found = true;
 				break;
 			}
@@ -2630,6 +2624,11 @@ static ssize_t recompress_store(struct d
 		ret = -EINVAL;
 		goto out;
 	}
+
+	if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	page = alloc_page(GFP_KERNEL);
 	if (!page) {
_

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

zram-do-not-permit-params-change-after-init.patch
zram-do-not-autocorrect-bad-recompression-parameters.patch
zram-drop-num_active_comps.patch
zram-update-recompression-documentation.patch
zram-remove-chained-recompression.patch
zram-unify-and-harden-algo-priority-params-handling.patch