diff options
| author | Jiri Olsa <jolsa@redhat.com> | 2013-03-19 15:35:09 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-05-01 12:34:46 +0200 |
| commit | 5919b30933d7c4fac1f214c59f26c5e990044f09 (patch) | |
| tree | 1d719e5fd6534ed0a6dd00927e3b8343bb725e50 /kernel | |
| parent | 1b0dac2ac6debdbf1541e15f2cede03613cf4465 (diff) | |
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')
| -rw-r--r-- | kernel/events/ring_buffer.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 97fddb09762b..cd55144270b5 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); |