Re: [PATCH 2/2] tracing: fprobe: Fix to remove recorded module addresses from filter

On Wed, 24 Sep 2025 11:49:39 +0800
menglong.dong@linux.dev wrote:

On 2025/9/24 08:26 Masami Hiramatsu (Google) [off-list ref] write:

quoted

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Even if there is a memory allocation failure in fprobe_addr_list_add(),
there is a partial list of module addresses. So remove the recorded
addresses from filter if exists.
This also removes the redundant ret local variable.

Fixes: a3dc2983ca7b ("tracing: fprobe: Cleanup fprobe hash when module unloading")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/trace/fprobe.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Hi, Masami. Should I send the V2 of the patch:

  tracing: fprobe: optimization for entry only case

after this series applied?

Yeah, I'll push this [2/2] to stable tonight. and
push [1/2] to probes/for-next too. I'll rebase probes/for-next
so that it will have both patch.

Thank you,

Thanks!
Menglong Dong

quoted

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 12ec194fdfed..95e43814b85b 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c

@@ -434,8 +434,9 @@ static int fprobe_addr_list_add(struct fprobe_addr_list *alist, unsigned long ad
 {
 	unsigned long *addrs;
 
-	if (alist->index >= alist->size)
-		return -ENOMEM;
+	/* Previously we failed to expand the list. */
+	if (alist->index == alist->size)
+		return -ENOSPC;
 
 	alist->addrs[alist->index++] = addr;
 	if (alist->index < alist->size)

@@ -497,7 +498,7 @@ static int fprobe_module_callback(struct notifier_block *nb,
 	} while (node == ERR_PTR(-EAGAIN));
 	rhashtable_walk_exit(&iter);
 
-	if (alist.index < alist.size && alist.index > 0)
+	if (alist.index > 0)
 		ftrace_set_filter_ips(&fprobe_graph_ops.ops,
 				      alist.addrs, alist.index, 1, 0);
 	mutex_unlock(&fprobe_mutex);

-- 
Masami Hiramatsu (Google) [off-list ref]