linux-kernel - [PATCHv3 09/11] zram: limit max recompress prio to num_active

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Message-ID: <20250130111105.2861324-10-senozhatsky@chromium.org>
Date: Thu, 30 Jan 2025 20:10:54 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Minchan Kim <minchan@...nel.org>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCHv3 09/11] zram: limit max recompress prio to num_active_comps

Use the actual number of algorithms zram was configure with
instead of theoretical limit of ZRAM_MAX_COMPS.

Also make sure that min prio is not above max prio.

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 drivers/block/zram/zram_drv.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index af4bce1e5fe1..3e91fd1dcfc7 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -2011,16 +2011,19 @@ static ssize_t recompress_store(struct device *dev,
 				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;
 	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);
@@ -2073,7 +2076,7 @@ static ssize_t recompress_store(struct device *dev,
 			if (prio == ZRAM_PRIMARY_COMP)
 				prio = ZRAM_SECONDARY_COMP;
 
-			prio_max = min(prio + 1, ZRAM_MAX_COMPS);
+			prio_max = prio + 1;
 			continue;
 		}
 	}
@@ -2087,6 +2090,12 @@ static ssize_t recompress_store(struct device *dev,
 		goto release_init_lock;
 	}
 
+	prio_max = min(prio_max, (u32)zram->num_active_comps);
+	if (prio >= prio_max) {
+		ret = -EINVAL;
+		goto release_init_lock;
+	}
+
 	/* Do not permit concurrent post-processing actions. */
 	if (atomic_xchg(&zram->pp_in_progress, 1)) {
 		up_read(&zram->init_lock);
@@ -2101,7 +2110,7 @@ static ssize_t recompress_store(struct device *dev,
 				continue;
 
 			if (!strcmp(zram->comp_algs[prio], algo)) {
-				prio_max = min(prio + 1, ZRAM_MAX_COMPS);
+				prio_max = prio + 1;
 				found = true;
 				break;
 			}
-- 
2.48.1.262.g85cc9f2d1e-goog