cma: tracing: print alloc result in trace_cma_alloc_finish

The result of the allocation attempt is not printed in
trace_cma_alloc_finish, but it's important to do it so we can set filters
to catch specific errors on allocation or to trigger some operations on
specific errors.

We have printed the result in log, but the log is conditional and could
not be filtered by tracing events.

It introduces little overhead to print this result.  The result of
allocation is named `errorno' in the trace.

Link: https://lkml.kernel.org/r/20221208142130.1501195-1-haowenchao@huawei.com
Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
index 3d708dae1542fddd0cca057df53e8177e852b553..ef75ea606ab261411e8332edb0369661c81dab05 100644 (file)
--- a/include/trace/events/cma.h
+++ b/include/trace/events/cma.h
@@ -91,12 +91,38 @@ TRACE_EVENT(cma_alloc_start,
                  __entry->align)
 );
 
-DEFINE_EVENT(cma_alloc_class, cma_alloc_finish,
+TRACE_EVENT(cma_alloc_finish,
 
        TP_PROTO(const char *name, unsigned long pfn, const struct page *page,
-                unsigned long count, unsigned int align),
+                unsigned long count, unsigned int align, int errorno),
 
-       TP_ARGS(name, pfn, page, count, align)
+       TP_ARGS(name, pfn, page, count, align, errorno),
+
+       TP_STRUCT__entry(
+               __string(name, name)
+               __field(unsigned long, pfn)
+               __field(const struct page *, page)
+               __field(unsigned long, count)
+               __field(unsigned int, align)
+               __field(int, errorno)
+       ),
+
+       TP_fast_assign(
+               __assign_str(name, name);
+               __entry->pfn = pfn;
+               __entry->page = page;
+               __entry->count = count;
+               __entry->align = align;
+               __entry->errorno = errorno;
+       ),
+
+       TP_printk("name=%s pfn=0x%lx page=%p count=%lu align=%u errorno=%d",
+                 __get_str(name),
+                 __entry->pfn,
+                 __entry->page,
+                 __entry->count,
+                 __entry->align,
+                 __entry->errorno)
 );
 
 DEFINE_EVENT(cma_alloc_class, cma_alloc_busy_retry,

diff --git a/mm/cma.c b/mm/cma.c
index 4a978e09547a88c734753632f488d317d2b83b2d..a75b17b03b66add6cf98b4ee4041c9434477f380 100644 (file)
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -491,7 +491,7 @@ struct page *cma_alloc(struct cma *cma, unsigned long count,
                start = bitmap_no + mask + 1;
        }
 
-       trace_cma_alloc_finish(cma->name, pfn, page, count, align);
+       trace_cma_alloc_finish(cma->name, pfn, page, count, align, ret);
 
        /*
         * CMA can allocate multiple page blocks, which results in different