From: Douglas Anderson dianders@chromium.org
[ Upstream commit 495fcec8648cdfb483b5b9ab310f3839f07cb3b8 ]
If you drop into kdb and type "ftdump" you'll get a sleeping while atomic warning from memory allocation in trace_find_next_entry().
This appears to have been caused by commit ff895103a84a ("tracing: Save off entry when peeking at next entry"), which added the allocation in that path. The problematic commit was already fixed by commit 8e99cf91b99b ("tracing: Do not allocate buffer in trace_find_next_entry() in atomic") but that fix missed the kdb case.
The fix here is easy: just move the assignment of the static buffer to the place where it should have been to begin with: trace_init_global_iter(). That function is called in two places, once is right before the assignment of the static buffer added by the previous fix and once is in kdb.
Note that it appears that there's a second static buffer that we need to assign that was added in commit efbbdaa22bb7 ("tracing: Show real address for trace event arguments"), so we'll move that too.
Link: https://lkml.kernel.org/r/20220708170919.1.I75844e5038d9425add2ad853a608cb44...
Fixes: ff895103a84a ("tracing: Save off entry when peeking at next entry") Fixes: efbbdaa22bb7 ("tracing: Show real address for trace event arguments") Signed-off-by: Douglas Anderson dianders@chromium.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/trace.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 518ce39a878d..f752f2574630 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9831,6 +9831,12 @@ void trace_init_global_iter(struct trace_iterator *iter) /* Output in nanoseconds only if we are using a clock in nanoseconds. */ if (trace_clocks[iter->tr->clock_id].in_ns) iter->iter_flags |= TRACE_FILE_TIME_IN_NS; + + /* Can not use kmalloc for iter.temp and iter.fmt */ + iter->temp = static_temp_buf; + iter->temp_size = STATIC_TEMP_BUF_SIZE; + iter->fmt = static_fmt_buf; + iter->fmt_size = STATIC_FMT_BUF_SIZE; }
void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) @@ -9863,11 +9869,6 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
/* Simulate the iterator */ trace_init_global_iter(&iter); - /* Can not use kmalloc for iter.temp and iter.fmt */ - iter.temp = static_temp_buf; - iter.temp_size = STATIC_TEMP_BUF_SIZE; - iter.fmt = static_fmt_buf; - iter.fmt_size = STATIC_FMT_BUF_SIZE;
for_each_tracing_cpu(cpu) { atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled);