Iterating code of /proc/kallsyms calls module_get_kallsym() which grabs and drops module_mutex internally and returns "struct module *", module is removed, aforementioned "struct module *" is used in non-trivial way.
So, grab module_mutex for entire operation like /proc/modules does. Steps to reproduce: while true; do modprobe xfs; rmmod xfs; done vs while true; do cat /proc/kallsyms >/dev/null; done ref:http://lkml.iu.edu/hypermail/linux/kernel/0703.1/2582.html https://bugzilla.kernel.org/show_bug.cgi?id=111541 Signed-off-by: Weilong Chen <[email protected]> --- kernel/kallsyms.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 3127ad5..aaecf19 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -515,6 +515,7 @@ static void *s_next(struct seq_file *m, void *p, loff_t *pos) static void *s_start(struct seq_file *m, loff_t *pos) { + mutex_lock(&module_mutex); if (!update_iter(m->private, *pos)) return NULL; return m->private; @@ -522,6 +523,7 @@ static void *s_start(struct seq_file *m, loff_t *pos) static void s_stop(struct seq_file *m, void *p) { + mutex_unlock(&module_mutex); } static int s_show(struct seq_file *m, void *p) -- 1.8.3.1
