From: Masami Hiramatsu (Google) <[email protected]>
unregister_fprobe() can fail under memory pressure because of memory
allocation failure, but this maybe called from module unloading, and
usually there is no way to retry it. Moreover. trace_fprobe does not
check the return value.
To fix this problem, unregister fprobe and fprobe_hash_node even if
working memory allocation fails.
Anyway, if the last fprobe is removed, the filter will be freed.
Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: [email protected]
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
---
Changes in v7:
- Newly added.
---
kernel/trace/fprobe.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index fc7018b28fdd..d634eb8e8b9e 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -934,15 +934,19 @@ int unregister_fprobe(struct fprobe *fp)
hlist_array = fp->hlist_array;
addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL);
- if (!addrs) {
- ret = -ENOMEM; /* TODO: Fallback to one-by-one loop */
- goto out;
- }
+ /*
+ * This will remove fprobe_hash_node from the hash table even if
+ * memory allocation fails. However, ftrace_ops will not be updated.
+ * Anyway, when the last fprobe is unregistered, ftrace_ops is also
+ * unregistered.
+ */
+ if (!addrs)
+ pr_warn("Failed to allocate working array. ftrace_ops may not
sync.\n");
/* Remove non-synonim ips from table and hash */
count = 0;
for (i = 0; i < hlist_array->size; i++) {
- if (!delete_fprobe_node(&hlist_array->array[i]))
+ if (!delete_fprobe_node(&hlist_array->array[i]) && addrs)
addrs[count++] = hlist_array->array[i].addr;
}
del_fprobe_hash(fp);
