> dump-pfn interface
> (it looks more clean and easier for review to fold patches 1-5 into one, but
> let's keep the changelog for the initial post)
>
> [RFC][PATCH 1/7] tracing/mm: add page frame snapshot trace
> [RFC][PATCH 2/7] tracing/mm: rename trigger file to dump-pfn
> [RFC][PATCH 3/7] tracing/mm: create trace_objects.c
> [RFC][PATCH 4/7] tracing/mm: dump more page frame information
> [RFC][PATCH 5/7] tracing/mm: accept echo-able input format for pfn range
For your convenience, here is the combined diff for the above 5 incremental ones.
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-mmotm/include/trace/events/mm.h 2011-08-29 11:57:16.000000000 +0800
@@ -0,0 +1,69 @@
+#if !defined(_TRACE_MM_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MM_H
+
+#include <linux/tracepoint.h>
+#include <linux/page-flags.h>
+#include <linux/mm.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mm
+
+extern struct trace_print_flags pageflag_names[];
+
+/**
+ * dump_page_frame - called by the trace page dump trigger
+ * @pfn: page frame number
+ * @page: pointer to the page frame
+ *
+ * This is a helper trace point into the dumping of the page frames.
+ * It will record various infromation about a page frame.
+ */
+TRACE_EVENT(dump_page_frame,
+
+ TP_PROTO(unsigned long pfn, struct page *page),
+
+ TP_ARGS(pfn, page),
+
+ TP_STRUCT__entry(
+ __field( unsigned long, pfn )
+ __field( struct page *, page )
+ __field( u64, stable_flags )
+ __field( unsigned long, flags )
+ __field( unsigned int, count )
+ __field( unsigned int, mapcount )
+ __field( unsigned long, private )
+ __field( unsigned long, mapping )
+ __field( unsigned long, index )
+ ),
+
+ TP_fast_assign(
+ __entry->pfn = pfn;
+ __entry->page = page;
+ __entry->stable_flags = stable_page_flags(page);
+ __entry->flags = page->flags;
+ __entry->count = atomic_read(&page->_count);
+ __entry->mapcount = page_mapcount(page);
+ __entry->private = page->private;
+ __entry->mapping = (unsigned long)page->mapping;
+ __entry->index = page->index;
+ ),
+
+ TP_printk("pfn=%lu page=%p count=%u mapcount=%u "
+ "private=%lx mapping=%lx index=%lx flags=%s",
+ __entry->pfn,
+ __entry->page,
+ __entry->count,
+ __entry->mapcount,
+ __entry->private,
+ __entry->mapping,
+ __entry->index,
+ ftrace_print_flags_seq(p, "|",
+ __entry->flags & PAGE_FLAGS_MASK,
+ pageflag_names)
+ )
+);
+
+#endif /* _TRACE_MM_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
--- linux-mmotm.orig/kernel/trace/Makefile 2011-08-28 10:09:25.000000000 +0800
+++ linux-mmotm/kernel/trace/Makefile 2011-08-28 10:09:28.000000000 +0800
@@ -26,6 +26,7 @@ obj-$(CONFIG_RING_BUFFER) += ring_buffer
obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
obj-$(CONFIG_TRACING) += trace.o
+obj-$(CONFIG_TRACING) += trace_objects.o
obj-$(CONFIG_TRACING) += trace_output.o
obj-$(CONFIG_TRACING) += trace_stat.o
obj-$(CONFIG_TRACING) += trace_printk.o
@@ -53,6 +54,7 @@ endif
obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
obj-$(CONFIG_TRACEPOINTS) += power-traces.o
+obj-$(CONFIG_EVENT_TRACING) += trace_mm.o
ifeq ($(CONFIG_TRACING),y)
obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
endif
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-mmotm/kernel/trace/trace_mm.c 2011-08-29 11:57:16.000000000 +0800
@@ -0,0 +1,150 @@
+/*
+ * Trace mm pages
+ *
+ * Copyright (C) 2009 Red Hat Inc, Steven Rostedt <srostedt@xxxxxxxxxx>
+ *
+ * Code based on Matt Mackall's /proc/[kpagecount|kpageflags] code.
+ */
+#include <linux/module.h>
+#include <linux/bootmem.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+
+#include "trace_output.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/mm.h>
+
+void trace_mm_page_frames(unsigned long start, unsigned long end,
+ void (*trace)(unsigned long pfn, struct page *page))
+{
+ unsigned long pfn = start;
+ struct page *page;
+
+ if (start > max_pfn - 1)
+ return;
+
+ if (end > max_pfn - 1)
+ end = max_pfn - 1;
+
+ while (pfn < end) {
+ page = NULL;
+ if (pfn_valid(pfn))
+ page = pfn_to_page(pfn);
+ pfn++;
+ if (page)
+ trace(pfn, page);
+ }
+}
+
+static void trace_mm_page_frame(unsigned long pfn, struct page *page)
+{
+ trace_dump_page_frame(pfn, page);
+}
+
+static ssize_t
+trace_mm_pfn_range_read(struct file *filp, char __user *ubuf, size_t cnt,
+ loff_t *ppos)
+{
+ return simple_read_from_buffer(ubuf, cnt, ppos, "0\n", 2);
+}
+
+
+static ssize_t
+trace_mm_pfn_range_write(struct file *filp, const char __user *ubuf, size_t cnt,
+ loff_t *ppos)
+{
+ unsigned long val, start, end;
+ char buf[64];
+ int ret;
+
+ if (cnt >= sizeof(buf))
+ return -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ if (tracing_update_buffers() < 0)
+ return -ENOMEM;
+
+ if (trace_set_clr_event("mm", "dump_page_frame", 1))
+ return -EINVAL;
+
+ buf[cnt] = 0;
+
+ ret = strict_strtol(buf, 10, &val);
+ if (ret < 0)
+ return ret;
+
+ start = *ppos;
+ if (val < 0)
+ end = max_pfn - 1;
+ else
+ end = start + val;
+
+ trace_mm_page_frames(start, end, trace_mm_page_frame);
+
+ *ppos += cnt;
+
+ return cnt;
+}
+
+static const struct file_operations trace_mm_fops = {
+ .open = tracing_open_generic,
+ .read = trace_mm_pfn_range_read,
+ .write = trace_mm_pfn_range_write,
+};
+
+static struct dentry *trace_objects_mm_dir(void)
+{
+ static struct dentry *d_mm;
+ struct dentry *d_objects;
+
+ if (d_mm)
+ return d_mm;
+
+ d_objects = trace_objects_dir();
+ if (!d_objects)
+ return NULL;
+
+ d_mm = debugfs_create_dir("mm", d_objects);
+ if (!d_mm)
+ pr_warning("Could not create 'objects/mm' directory\n");
+
+ return d_mm;
+}
+
+static struct dentry *trace_objects_mm_pages_dir(void)
+{
+ static struct dentry *d_pages;
+ struct dentry *d_mm;
+
+ if (d_pages)
+ return d_pages;
+
+ d_mm = trace_objects_mm_dir();
+ if (!d_mm)
+ return NULL;
+
+ d_pages = debugfs_create_dir("pages", d_mm);
+ if (!d_pages)
+ pr_warning("Could not create debugfs "
+ "'objects/mm/pages' directory\n");
+
+ return d_pages;
+}
+
+static __init int trace_objects_mm_init(void)
+{
+ struct dentry *d_pages;
+
+ d_pages = trace_objects_mm_pages_dir();
+ if (!d_pages)
+ return 0;
+
+ trace_create_file("dump-pfn", 0600, d_pages, NULL,
+ &trace_mm_fops);
+
+ return 0;
+}
+fs_initcall(trace_objects_mm_init);
--- linux-mmotm.orig/kernel/trace/trace.h 2011-08-28 10:09:25.000000000 +0800
+++ linux-mmotm/kernel/trace/trace.h 2011-08-28 10:09:28.000000000 +0800
@@ -318,6 +318,7 @@ struct dentry *trace_create_file(const c
const struct file_operations *fops);
struct dentry *tracing_init_dentry(void);
+struct dentry *trace_objects_dir(void);
struct ring_buffer_event;
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-mmotm/kernel/trace/trace_objects.c 2011-08-28 10:09:28.000000000 +0800
@@ -0,0 +1,26 @@
+#include <linux/debugfs.h>
+
+#include "trace.h"
+#include "trace_output.h"
+
+struct dentry *trace_objects_dir(void)
+{
+ static struct dentry *d_objects;
+ struct dentry *d_tracer;
+
+ if (d_objects)
+ return d_objects;
+
+ d_tracer = tracing_init_dentry();
+ if (!d_tracer)
+ return NULL;
+
+ d_objects = debugfs_create_dir("objects", d_tracer);
+ if (!d_objects)
+ pr_warning("Could not create debugfs "
+ "'objects' directory\n");
+
+ return d_objects;
+}
+
+
--- linux-mmotm.orig/mm/page_alloc.c 2011-08-29 10:43:01.000000000 +0800
+++ linux-mmotm/mm/page_alloc.c 2011-08-29 10:43:03.000000000 +0800
@@ -5743,7 +5743,7 @@ bool is_free_buddy_page(struct page *pag
}
#endif
-static struct trace_print_flags pageflag_names[] = {
+struct trace_print_flags pageflag_names[] = {
{1UL << PG_locked, "locked" },
{1UL << PG_error, "error" },
{1UL << PG_referenced, "referenced" },
@@ -5790,7 +5790,7 @@ static void dump_page_flags(unsigned lon
printk(KERN_ALERT "page flags: %#lx(", flags);
/* remove zone id */
- flags &= (1UL << NR_PAGEFLAGS) - 1;
+ flags &= PAGE_FLAGS_MASK;
for (i = 0; pageflag_names[i].name && flags; i++) {
--- linux-mmotm.orig/include/linux/page-flags.h 2011-08-29 10:43:01.000000000 +0800
+++ linux-mmotm/include/linux/page-flags.h 2011-08-29 10:43:03.000000000 +0800
@@ -462,6 +462,7 @@ static inline int PageTransCompound(stru
* there has been a kernel bug or struct page corruption.
*/
#define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
+#define PAGE_FLAGS_MASK ((1 << NR_PAGEFLAGS) - 1)
#define PAGE_FLAGS_PRIVATE \
(1 << PG_private | 1 << PG_private_2)
--
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