summaryrefslogtreecommitdiff
path: root/mm/slub.c
diff options
context:
space:
mode:
authorImran Khan <imran.f.khan@oracle.com>2022-08-14 22:53:53 +0300
committerAndrew Morton <akpm@linux-foundation.org>2022-09-12 06:25:52 +0300
commitb84e04f1baeebe6872b22a027cfc558621e842d4 (patch)
tree144f0b2e5357717a15231f00013e6cabbc2c8b99 /mm/slub.c
parent831568214883e0a9940f776771343420306d2341 (diff)
downloadlinux-b84e04f1baeebe6872b22a027cfc558621e842d4.tar.xz
kfence: add sysfs interface to disable kfence for selected slabs.
By default kfence allocation can happen for any slab object, whose size is up to PAGE_SIZE, as long as that allocation is the first allocation after expiration of kfence sample interval. But in certain debugging scenarios we may be interested in debugging corruptions involving some specific slub objects like dentry or ext4_* etc. In such cases limiting kfence for allocations involving only specific slub objects will increase the probablity of catching the issue since kfence pool will not be consumed by other slab objects. This patch introduces a sysfs interface '/sys/kernel/slab/<name>/skip_kfence' to disable kfence for specific slabs. Having the interface work in this way does not impact current/default behavior of kfence and allows us to use kfence for specific slabs (when needed) as well. The decision to skip/use kfence is taken depending on whether kmem_cache.flags has (newly introduced) SLAB_SKIP_KFENCE flag set or not. Link: https://lkml.kernel.org/r/20220814195353.2540848-1-imran.f.khan@oracle.com Signed-off-by: Imran Khan <imran.f.khan@oracle.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 862dbd9af4f5..6953c3367bc2 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5745,6 +5745,29 @@ STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
#endif /* CONFIG_SLUB_STATS */
+#ifdef CONFIG_KFENCE
+static ssize_t skip_kfence_show(struct kmem_cache *s, char *buf)
+{
+ return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_SKIP_KFENCE));
+}
+
+static ssize_t skip_kfence_store(struct kmem_cache *s,
+ const char *buf, size_t length)
+{
+ int ret = length;
+
+ if (buf[0] == '0')
+ s->flags &= ~SLAB_SKIP_KFENCE;
+ else if (buf[0] == '1')
+ s->flags |= SLAB_SKIP_KFENCE;
+ else
+ ret = -EINVAL;
+
+ return ret;
+}
+SLAB_ATTR(skip_kfence);
+#endif
+
static struct attribute *slab_attrs[] = {
&slab_size_attr.attr,
&object_size_attr.attr,
@@ -5812,6 +5835,9 @@ static struct attribute *slab_attrs[] = {
&failslab_attr.attr,
#endif
&usersize_attr.attr,
+#ifdef CONFIG_KFENCE
+ &skip_kfence_attr.attr,
+#endif
NULL
};