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-rw-r--r--include/linux/writeback.h2
-rw-r--r--kernel/trace/trace.c38
-rw-r--r--mm/page-writeback.c10
3 files changed, 47 insertions, 3 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index f462439..bd91987 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -105,6 +105,8 @@ extern int vm_highmem_is_dirtyable;
extern int block_dump;
extern int laptop_mode;
+extern unsigned long determine_dirtyable_memory(void);
+
extern int dirty_ratio_handler(struct ctl_table *table, int write,
struct file *filp, void __user *buffer, size_t *lenp,
loff_t *ppos);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 82ced40..2824cf48 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -27,6 +27,7 @@
#include <linux/poll.h>
#include <linux/gfp.h>
#include <linux/fs.h>
+#include <linux/writeback.h>
#include <linux/stacktrace.h>
@@ -51,6 +52,8 @@ static int trace_free_page(void);
static int tracing_disabled = 1;
+static unsigned long tracing_pages_allocated;
+
long
ns2usecs(cycle_t nsec)
{
@@ -2591,12 +2594,41 @@ tracing_entries_write(struct file *filp, const char __user *ubuf,
}
if (val > global_trace.entries) {
+ long pages_requested;
+ unsigned long freeable_pages;
+
+ /* make sure we have enough memory before mapping */
+ pages_requested =
+ (val + (ENTRIES_PER_PAGE-1)) / ENTRIES_PER_PAGE;
+
+ /* account for each buffer (and max_tr) */
+ pages_requested *= tracing_nr_buffers * 2;
+
+ /* Check for overflow */
+ if (pages_requested < 0) {
+ cnt = -ENOMEM;
+ goto out;
+ }
+
+ freeable_pages = determine_dirtyable_memory();
+
+ /* we only allow to request 1/4 of useable memory */
+ if (pages_requested >
+ ((freeable_pages + tracing_pages_allocated) / 4)) {
+ cnt = -ENOMEM;
+ goto out;
+ }
+
while (global_trace.entries < val) {
if (trace_alloc_page()) {
cnt = -ENOMEM;
goto out;
}
+ /* double check that we don't go over the known pages */
+ if (tracing_pages_allocated > pages_requested)
+ break;
}
+
} else {
/* include the number of entries in val (inc of page entries) */
while (global_trace.entries > val + (ENTRIES_PER_PAGE - 1))
@@ -2776,6 +2808,7 @@ static int trace_alloc_page(void)
struct page *page, *tmp;
LIST_HEAD(pages);
void *array;
+ unsigned pages_allocated = 0;
int i;
/* first allocate a page for each CPU */
@@ -2787,6 +2820,7 @@ static int trace_alloc_page(void)
goto free_pages;
}
+ pages_allocated++;
page = virt_to_page(array);
list_add(&page->lru, &pages);
@@ -2798,6 +2832,7 @@ static int trace_alloc_page(void)
"for trace buffer!\n");
goto free_pages;
}
+ pages_allocated++;
page = virt_to_page(array);
list_add(&page->lru, &pages);
#endif
@@ -2819,6 +2854,7 @@ static int trace_alloc_page(void)
SetPageLRU(page);
#endif
}
+ tracing_pages_allocated += pages_allocated;
global_trace.entries += ENTRIES_PER_PAGE;
return 0;
@@ -2853,6 +2889,8 @@ static int trace_free_page(void)
page = list_entry(p, struct page, lru);
ClearPageLRU(page);
list_del(&page->lru);
+ tracing_pages_allocated--;
+ tracing_pages_allocated--;
__free_page(page);
tracing_reset(data);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 789b6ad..b38f700 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -126,8 +126,6 @@ static void background_writeout(unsigned long _min_pages);
static struct prop_descriptor vm_completions;
static struct prop_descriptor vm_dirties;
-static unsigned long determine_dirtyable_memory(void);
-
/*
* couple the period to the dirty_ratio:
*
@@ -347,7 +345,13 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
#endif
}
-static unsigned long determine_dirtyable_memory(void)
+/**
+ * determine_dirtyable_memory - amount of memory that may be used
+ *
+ * Returns the numebr of pages that can currently be freed and used
+ * by the kernel for direct mappings.
+ */
+unsigned long determine_dirtyable_memory(void)
{
unsigned long x;