[PATCH] crypto/async_pq: use __free_page() instead of put_page()

[PATCH] crypto/async_pq: use __free_page() instead of put_page()

[Arnd Bergmann]

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.

Fixes: 0f80830dd044 ("mm/page_ref: add tracepoint to track down page reference manipulation")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 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);
-- 
2.7.0

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Re: [PATCH] crypto/async_pq: use __free_page() instead of put_page()

[Dan Williams]

On Mon, Feb 29, 2016 at 1:33 AM, Arnd Bergmann <arnd@arndb.de> 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.
>
> Fixes: 0f80830dd044 ("mm/page_ref: add tracepoint to track down page reference manipulation")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Dan Williams <dan.j.williams@intel.com>

Vinod, will you take this one?

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Re: [PATCH] crypto/async_pq: use __free_page() instead of put_page()

[Joonsoo Kim]

2016-03-01 3:04 GMT+09:00 Dan Williams <dan.j.williams@intel.com>:
> On Mon, Feb 29, 2016 at 1:33 AM, Arnd Bergmann <arnd@arndb.de> 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.
>>
>> Fixes: 0f80830dd044 ("mm/page_ref: add tracepoint to track down page reference manipulation")
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Acked-by: Dan Williams <dan.j.williams@intel.com>
>
> Vinod, will you take this one?

Problematic patch ("mm/page_ref: ~~~") is not yet merged one. It is on mmotm
and this fix should go together with it or before it. I think that
handling this fix by
Andrew is easier to all.

Thanks.

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Re: [PATCH] crypto/async_pq: use __free_page() instead of put_page()

[Vinod Koul]

On Tue, Mar 01, 2016 at 10:54:50PM +0900, Joonsoo Kim wrote:
> 2016-03-01 3:04 GMT+09:00 Dan Williams <dan.j.williams@intel.com>:
> > On Mon, Feb 29, 2016 at 1:33 AM, Arnd Bergmann <arnd@arndb.de> 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.
> >>
> >> Fixes: 0f80830dd044 ("mm/page_ref: add tracepoint to track down page reference manipulation")
> >> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >
> > Acked-by: Dan Williams <dan.j.williams@intel.com>
> >
> > Vinod, will you take this one?
> 
> Problematic patch ("mm/page_ref: ~~~") is not yet merged one. It is on mmotm
> and this fix should go together with it or before it. I think that
> handling this fix by
> Andrew is easier to all.

Okay fine by me.

-- 
~Vinod

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Re: [PATCH] crypto/async_pq: use __free_page() instead of put_page()

[Vlastimil Babka]

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 <arnd@arndb.de>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  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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