On 02/29/2016 10:33 AM, Arnd Bergmann wrote:
> The addition of tracepoints to the page reference tracking had an
> unfortunate side-effect in at least one driver that calls put_page
> from its exit function, resulting in a link error:
>
> `.exit.text' referenced in section `__jump_table' of crypto/built-in.o:
> defined in discarded section `.exit.text' of crypto/built-in.o
>
> From a cursory look at that this driver, it seems that it may be
> doing the wrong thing here anyway, as the page gets allocated
> using 'alloc_page()', and should be freed using '__free_page()'
> rather than 'put_page()'.
>
> With this patch, I no longer get any other build errors from the
> page_ref patch, so hopefully we can assume that it's always wrong
> to call any of those functions from __exit code, and that no other
> driver does it.
Hopefully that's true. If any such driver was leaking references to
those pages, so the put_page() didn't actually result in freeing, the
explicit __free_page should catch this via built-in checks.
> Fixes: 0f80830dd044 ("mm/page_ref: add tracepoint to track down page
> reference manipulation")
Since it's in mmotm which is quilt-based, the commit hash from -next is
not stable.
> Signed-off-by: Arnd Bergmann
Acked-by: Vlastimil Babka
> ---
> crypto/async_tx/async_pq.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
> index c0748bbd4c08..08b3ac68952b 100644
> --- a/crypto/async_tx/async_pq.c
> +++ b/crypto/async_tx/async_pq.c
> @@ -444,7 +444,7 @@ static int __init async_pq_init(void)
>
> static void __exit async_pq_exit(void)
> {
> - put_page(pq_scribble_page);
> + __free_page(pq_scribble_page);
> }
>
> module_init(async_pq_init);
>
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