The patch titled
Subject: mm/slub: fix endianness bug for alloc/free_traces attributes
has been added to the -mm tree. Its filename is
mm-slub-fix-endianness-bug-for-alloc-free_traces-attributes.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-slub-fix-endianness-bug-for-alloc-free_traces-attributes.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-slub-fix-endianness-bug-for-alloc-free_traces-attributes.patch
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------------------------------------------------------
From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Subject: mm/slub: fix endianness bug for alloc/free_traces attributes
On big-endian s390, the alloc/free_traces attributes produce endless
output, because of always 0 idx in slab_debugfs_show().
idx is de-referenced from *v, which points to a loff_t value, with
unsigned int idx = *(unsigned int *)v;
This will only give the upper 32 bits on big-endian, which remain 0.
Instead of only fixing this de-reference, during discussion it seemed more
appropriate to change the seq_ops so that they use an explicit iterator in
private loc_track struct.
This patch adds idx to loc_track, which will also fix the endianness bug.
Link: https://lore.kernel.org/r/20211117193932.4049412-1-gerald.schaefer@xxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20211126171848.17534-1-gerald.schaefer@xxxxxxxxxxxxx
Fixes: 64dd68497be7 ("mm: slub: move sysfs slab alloc/free interfaces to debugfs")
Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Reported-by: Steffen Maier <maier@xxxxxxxxxxxxx>
Cc: : Vlastimil Babka <vbabka@xxxxxxx>
Cc: Faiyaz Mohammed <faiyazm@xxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
--- a/mm/slub.c~mm-slub-fix-endianness-bug-for-alloc-free_traces-attributes
+++ a/mm/slub.c
@@ -5081,6 +5081,7 @@ struct loc_track {
unsigned long max;
unsigned long count;
struct location *loc;
+ loff_t idx;
};
static struct dentry *slab_debugfs_root;
@@ -6052,11 +6053,11 @@ __initcall(slab_sysfs_init);
#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)
static int slab_debugfs_show(struct seq_file *seq, void *v)
{
-
- struct location *l;
- unsigned int idx = *(unsigned int *)v;
struct loc_track *t = seq->private;
+ struct location *l;
+ unsigned long idx;
+ idx = (unsigned long) t->idx;
if (idx < t->count) {
l = &t->loc[idx];
@@ -6105,16 +6106,18 @@ static void *slab_debugfs_next(struct se
{
struct loc_track *t = seq->private;
- v = ppos;
- ++*ppos;
+ t->idx = ++(*ppos);
if (*ppos <= t->count)
- return v;
+ return ppos;
return NULL;
}
static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
{
+ struct loc_track *t = seq->private;
+
+ t->idx = *ppos;
return ppos;
}
_
Patches currently in -mm which might be from gerald.schaefer@xxxxxxxxxxxxx are
mm-slub-fix-endianness-bug-for-alloc-free_traces-attributes.patch
