Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
tracing/fprobe: Unregister fprobe even if memory allocation fails
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.
Link: https://lore.kernel.org/all/177669365629.132053.8433032896213721288.stgit@mhiramat.tok.corp.google.com/
Fixes: 4346ba160409 ("fprobe: Rewrite fprobe on function-graph tracer")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
+15
-10
+15
-10
kernel/trace/fprobe.c
+15
-10
kernel/trace/fprobe.c
···
324
324
lockdep_assert_held(&fprobe_mutex);
325
325
326
326
fprobe_ftrace_active--;
327
-
if (!fprobe_ftrace_active)
327
+
if (!fprobe_ftrace_active) {
328
328
unregister_ftrace_function(&fprobe_ftrace_ops);
329
-
if (num)
329
+
ftrace_free_filter(&fprobe_ftrace_ops);
330
+
} else if (num)
330
331
ftrace_set_filter_ips(&fprobe_ftrace_ops, addrs, num, 1, 0);
331
332
}
332
333
···
526
525
527
526
fprobe_graph_active--;
528
527
/* Q: should we unregister it ? */
529
-
if (!fprobe_graph_active)
528
+
if (!fprobe_graph_active) {
530
529
unregister_ftrace_graph(&fprobe_graph_ops);
531
-
532
-
if (num)
530
+
ftrace_free_filter(&fprobe_graph_ops.ops);
531
+
} else if (num)
533
532
ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0);
534
533
}
535
534
···
933
932
934
933
hlist_array = fp->hlist_array;
935
934
addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL);
936
-
if (!addrs) {
937
-
ret = -ENOMEM; /* TODO: Fallback to one-by-one loop */
938
-
goto out;
939
-
}
935
+
/*
936
+
* This will remove fprobe_hash_node from the hash table even if
937
+
* memory allocation fails. However, ftrace_ops will not be updated.
938
+
* Anyway, when the last fprobe is unregistered, ftrace_ops is also
939
+
* unregistered.
940
+
*/
941
+
if (!addrs)
942
+
pr_warn("Failed to allocate working array. ftrace_ops may not sync.\n");
940
943
941
944
/* Remove non-synonim ips from table and hash */
942
945
count = 0;
943
946
for (i = 0; i < hlist_array->size; i++) {
944
-
if (!delete_fprobe_node(&hlist_array->array[i]))
947
+
if (!delete_fprobe_node(&hlist_array->array[i]) && addrs)
945
948
addrs[count++] = hlist_array->array[i].addr;
946
949
}
947
950
del_fprobe_hash(fp);