tracing: Fix preempt count leak (1dbd1951) · Commits · 戴 / test

While running my ftrace stress test, this showed up: BUG: sleeping function called from invalid context at mm/mmap.c:233 ... note: cat[3293] exited with preempt_count 1 The bug was introduced by commit ("tracing: Fix recursive user stack trace") Cc: <stable@kernel.org> Signed-off-by:

Li Zefan <lizf@cn.fujitsu.com> LKML-Reference: <4D0089AC.1020802@cn.fujitsu.com> Signed-off-by:

Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -1313,12 +1313,10 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)

		__this_cpu_inc(user_stack_count);



		event = trace_buffer_lock_reserve(buffer, TRACE_USER_STACK,
		sizeof(*entry), flags, pc);
		if (!event)
		return;
		goto out_drop_count;
		entry = ring_buffer_event_data(event);

		entry->tgid = current->tgid;
		@@ -1333,8 +1331,8 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)
		if (!filter_check_discard(call, entry, buffer, event))
		ring_buffer_unlock_commit(buffer, event);

		out_drop_count:
		__this_cpu_dec(user_stack_count);

		out:
		preempt_enable();
		}

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