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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>
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5919b30933
1 changed files with 10 additions and 4 deletions
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@ -326,11 +326,16 @@ void rb_free(struct ring_buffer *rb)
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}
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}
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#else
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#else
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static int data_page_nr(struct ring_buffer *rb)
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{
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return rb->nr_pages << page_order(rb);
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}
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struct page *
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struct page *
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perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
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perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
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{
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{
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if (pgoff > (1UL << page_order(rb)))
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/* The '>' counts in the user page. */
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if (pgoff > data_page_nr(rb))
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return NULL;
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return NULL;
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return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
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return vmalloc_to_page((void *)rb->user_page + pgoff * PAGE_SIZE);
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@ -350,10 +355,11 @@ static void rb_free_work(struct work_struct *work)
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int i, nr;
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int i, nr;
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rb = container_of(work, struct ring_buffer, work);
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rb = container_of(work, struct ring_buffer, work);
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nr = 1 << page_order(rb);
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nr = data_page_nr(rb);
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base = rb->user_page;
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base = rb->user_page;
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for (i = 0; i < nr + 1; i++)
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/* The '<=' counts in the user page. */
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for (i = 0; i <= nr; i++)
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perf_mmap_unmark_page(base + (i * PAGE_SIZE));
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perf_mmap_unmark_page(base + (i * PAGE_SIZE));
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vfree(base);
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vfree(base);
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@ -387,7 +393,7 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags)
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rb->user_page = all_buf;
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rb->user_page = all_buf;
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rb->data_pages[0] = all_buf + PAGE_SIZE;
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rb->data_pages[0] = all_buf + PAGE_SIZE;
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rb->page_order = ilog2(nr_pages);
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rb->page_order = ilog2(nr_pages);
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rb->nr_pages = 1;
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rb->nr_pages = !!nr_pages;
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ring_buffer_init(rb, watermark, flags);
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ring_buffer_init(rb, watermark, flags);
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