linux-kernel - [PATCH V2] mm/damon/schemes: Add the validity judgment of thresholds

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Date:   Thu, 18 Nov 2021 20:46:24 +0800
From:   Xin Hao <xhao@...ux.alibaba.com>
To:     sj@...nel.org
Cc:     xhao@...ux.alibaba.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH V2] mm/damon/schemes: Add the validity judgment of thresholds

In dbgfs "schemes" interface, i do some test like this:
    # cd /sys/kernel/debug/damon
    # echo "2 1 2 1 10 1 3 10 1 1 1 1 1 1 1 1 2 3" > schemes
    # cat schemes
    # 2 1 2 1 10 1 3 10 1 1 1 1 1 1 1 1 2 3 0 0

There have some unreasonable places, i set the valules of these variables
"<min_sz, max_sz> <min_nr_a, max_nr_a>, <min_age, max_age>, <wmarks.high,
wmarks.mid, wmarks.low>" as "<2, 1>, <2, 1>, <10, 1>, <1, 2, 3>.

So there add a validity judgment for these thresholds value.

Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
---
 mm/damon/dbgfs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index befb27a29aab..4a96cd4df24f 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -215,6 +215,13 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
 			goto fail;
 		}

+		if (min_sz > max_sz || min_nr_a > max_nr_a || min_age > max_age)
+			goto fail;
+
+		if (wmarks.high < wmarks.mid || wmarks.high < wmarks.low ||
+		    wmarks.mid <  wmarks.low)
+			goto fail;
+
 		pos += parsed;
 		scheme = damon_new_scheme(min_sz, max_sz, min_nr_a, max_nr_a,
 				min_age, max_age, action, &quota, &wmarks);
--
2.31.0