Patch "mm/damon/sysfs: fix wrong empty schemes assumption under online tuning in damon_sysfs_set_schemes()" has been added to the 6.0-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mm/damon/sysfs: fix wrong empty schemes assumption under online tuning in damon_sysfs_set_schemes()

to the 6.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mm-damon-sysfs-fix-wrong-empty-schemes-assumption-under-online-tuning-in-damon_sysfs_set_schemes.patch
and it can be found in the queue-6.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 95bc35f9bee5220dad4e8567654ab3288a181639 Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@xxxxxxxxxx>
Date: Tue, 22 Nov 2022 19:48:31 +0000
Subject: mm/damon/sysfs: fix wrong empty schemes assumption under online tuning in damon_sysfs_set_schemes()

From: SeongJae Park <sj@xxxxxxxxxx>

commit 95bc35f9bee5220dad4e8567654ab3288a181639 upstream.

Commit da87878010e5 ("mm/damon/sysfs: support online inputs update") made
'damon_sysfs_set_schemes()' to be called for running DAMON context, which
could have schemes.  In the case, DAMON sysfs interface is supposed to
update, remove, or add schemes to reflect the sysfs files.  However, the
code is assuming the DAMON context wouldn't have schemes at all, and
therefore creates and adds new schemes.  As a result, the code doesn't
work as intended for online schemes tuning and could have more than
expected memory footprint.  The schemes are all in the DAMON context, so
it doesn't leak the memory, though.

Remove the wrong asssumption (the DAMON context wouldn't have schemes) in
'damon_sysfs_set_schemes()' to fix the bug.

Link: https://lkml.kernel.org/r/20221122194831.3472-1-sj@xxxxxxxxxx
Fixes: da87878010e5 ("mm/damon/sysfs: support online inputs update")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[5.19+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 mm/damon/sysfs.c |   46 ++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 44 insertions(+), 2 deletions(-)

--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -2286,12 +2286,54 @@ static struct damos *damon_sysfs_mk_sche
 			sysfs_scheme->action, &quota, &wmarks);
 }
 
+static void damon_sysfs_update_scheme(struct damos *scheme,
+		struct damon_sysfs_scheme *sysfs_scheme)
+{
+	struct damon_sysfs_access_pattern *access_pattern =
+		sysfs_scheme->access_pattern;
+	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
+	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
+	struct damon_sysfs_watermarks *sysfs_wmarks = sysfs_scheme->watermarks;
+
+	scheme->pattern.min_sz_region = access_pattern->sz->min;
+	scheme->pattern.max_sz_region = access_pattern->sz->max;
+	scheme->pattern.min_nr_accesses = access_pattern->nr_accesses->min;
+	scheme->pattern.max_nr_accesses = access_pattern->nr_accesses->max;
+	scheme->pattern.min_age_region = access_pattern->age->min;
+	scheme->pattern.max_age_region = access_pattern->age->max;
+
+	scheme->action = sysfs_scheme->action;
+
+	scheme->quota.ms = sysfs_quotas->ms;
+	scheme->quota.sz = sysfs_quotas->sz;
+	scheme->quota.reset_interval = sysfs_quotas->reset_interval_ms;
+	scheme->quota.weight_sz = sysfs_weights->sz;
+	scheme->quota.weight_nr_accesses = sysfs_weights->nr_accesses;
+	scheme->quota.weight_age = sysfs_weights->age;
+
+	scheme->wmarks.metric = sysfs_wmarks->metric;
+	scheme->wmarks.interval = sysfs_wmarks->interval_us;
+	scheme->wmarks.high = sysfs_wmarks->high;
+	scheme->wmarks.mid = sysfs_wmarks->mid;
+	scheme->wmarks.low = sysfs_wmarks->low;
+}
+
 static int damon_sysfs_set_schemes(struct damon_ctx *ctx,
 		struct damon_sysfs_schemes *sysfs_schemes)
 {
-	int i;
+	struct damos *scheme, *next;
+	int i = 0;
+
+	damon_for_each_scheme_safe(scheme, next, ctx) {
+		if (i < sysfs_schemes->nr)
+			damon_sysfs_update_scheme(scheme,
+					sysfs_schemes->schemes_arr[i]);
+		else
+			damon_destroy_scheme(scheme);
+		i++;
+	}
 
-	for (i = 0; i < sysfs_schemes->nr; i++) {
+	for (; i < sysfs_schemes->nr; i++) {
 		struct damos *scheme, *next;
 
 		scheme = damon_sysfs_mk_scheme(sysfs_schemes->schemes_arr[i]);


Patches currently in stable-queue which might be from sj@xxxxxxxxxx are

queue-6.0/mm-damon-sysfs-fix-wrong-empty-schemes-assumption-under-online-tuning-in-damon_sysfs_set_schemes.patch