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authorJiri Olsa <jolsa@redhat.com>2013-03-19 15:35:09 +0100
committerIngo Molnar <mingo@kernel.org>2013-05-01 12:34:46 +0200
commit5919b30933d7c4fac1f214c59f26c5e990044f09 (patch)
tree1d719e5fd6534ed0a6dd00927e3b8343bb725e50 /kernel/events
parent1b0dac2ac6debdbf1541e15f2cede03613cf4465 (diff)
downloadvexpress-lsk-5919b30933d7c4fac1f214c59f26c5e990044f09.tar.gz
perf: Fix vmalloc ring buffer pages handling
If we allocate perf ring buffer with the size of single (user) page, we will get memory corruption when releasing itin rb_free_work function (for CONFIG_PERF_USE_VMALLOC option). For single page sized ring buffer the page_order is -1 (because nr_pages is 0). This needs to be recognized in the rb_free_work function to release proper amount of pages. Adding data_page_nr function that returns number of allocated data pages. Customizing the rest of the code to use it. Reported-by: Jan Stancek <jstancek@redhat.com> Original-patch-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Jiri Olsa <jolsa@redhat.com> Link: http://lkml.kernel.org/r/20130319143509.GA1128@krava.brq.redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/ring_buffer.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 97fddb09762..cd55144270b 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -326,11 +326,16 @@ void rb_free(struct ring_buffer *rb)
}
#else
+static int data_page_nr(struct ring_buffer *rb)
+{
+ return rb->nr_pages << page_order(rb);
+}
struct page *
perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
{
- if (pgoff > (1UL << page_order(rb)))
+ /* The '>' counts in the user page. */
+ if (pgoff > data_page_nr(rb))
return NULL;
return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
@@ -350,10 +355,11 @@ static void rb_free_work(struct work_struct *work)
int i, nr;
rb = container_of(work, struct ring_buffer, work);
- nr = 1 << page_order(rb);
+ nr = data_page_nr(rb);
base = rb->user_page;
- for (i = 0; i < nr + 1; i++)
+ /* The '<=' counts in the user page. */
+ for (i = 0; i <= nr; i++)
perf_mmap_unmark_page(base + (i * PAGE_SIZE));
vfree(base);
@@ -387,7 +393,7 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
rb->user_page = all_buf;
rb->data_pages[0] = all_buf + PAGE_SIZE;
rb->page_order = ilog2(nr_pages);
- rb->nr_pages = 1;
+ rb->nr_pages = !!nr_pages;
ring_buffer_init(rb, watermark, flags);