The following commit has been merged into the perf/core branch of tip: Commit-ID: 112a0e4171e111e963aada3fe790c71accf4d705 Gitweb: https://git.kernel.org/tip/112a0e4171e111e963aada3fe790c71accf4d705 Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx> AuthorDate: Tue, 28 Jul 2020 16:34:00 +09:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 28 Jul 2020 13:19:05 +02:00 kprobes: Remove unnecessary module_mutex locking from kprobe_optimizer() Since we already lock both kprobe_mutex and text_mutex in the optimizer, text will not be changed and the module unloading will be stopped inside kprobes_module_callback(). The mutex_lock() has originally been introduced to avoid conflict with text modification, at that point we didn't hold text_mutex. But after: f1c6ece23729 ("kprobes: Fix potential deadlock in kprobe_optimizer()") We started holding the text_mutex and don't need the modules mutex anyway. So remove the module_mutex locking. [ mingo: Amended the changelog. ] Suggested-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20200728163400.e00b09c594763349f99ce6cb@xxxxxxxxxx --- kernel/kprobes.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 146c648..e87679a 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -598,8 +598,6 @@ static void kprobe_optimizer(struct work_struct *work) mutex_lock(&kprobe_mutex); cpus_read_lock(); mutex_lock(&text_mutex); - /* Lock modules while optimizing kprobes */ - mutex_lock(&module_mutex); /* * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) @@ -624,7 +622,6 @@ static void kprobe_optimizer(struct work_struct *work) /* Step 4: Free cleaned kprobes after quiesence period */ do_free_cleaned_kprobes(); - mutex_unlock(&module_mutex); mutex_unlock(&text_mutex); cpus_read_unlock();
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