Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

[Qu Wenruo]

Adding S390 to the mailing list, I got the incorrect address in the 
initial patch.

Much appreciated if S390 people can give it a test.

Thanks,
Qu


在 2026/1/19 16:24, Qu Wenruo 写道:
> [BUG]
> After commit aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration
> buffer preparation"), we no longer release the folio of the page cache
> of folio returned by btrfs_compress_filemap_get_folio() for S390
> hardware accerlation path.
> 
> [CAUSE]
> Before that commit, we call kumap_local() and folio_put() after handling
> each folio.
> 
> Although the timing is not ideal (it release previous folio at the
> beginning of the loop, and rely on some extra cleanup out of the loop),
> it at least handles the folio release correctly.
> 
> Meanwhile the refactored code is easier to read, it lacks the call to
> release the filemap folio.
> 
> [FIX]
> Add the missing folio_put() for copy_data_into_buffer().
> 
> Cc: linux-s390@vger.kernel.orgaa60fe12b4f49f49fc73e5023f8675e2df1f7805
> Fixes: aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration buffer preparation")
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>   fs/btrfs/zlib.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
> index 6caba8be7c84..10ed48d4a846 100644
> --- a/fs/btrfs/zlib.c
> +++ b/fs/btrfs/zlib.c
> @@ -139,6 +139,7 @@ static int copy_data_into_buffer(struct address_space *mapping,
>   		data_in = kmap_local_folio(folio, offset);
>   		memcpy(workspace->buf + cur - filepos, data_in, copy_length);
>   		kunmap_local(data_in);
> +		folio_put(folio);
>   		cur += copy_length;
>   	}
>   	return 0;

Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

[Heiko Carstens]

On Wed, Jan 21, 2026 at 09:22:47AM +1030, Qu Wenruo wrote:
> Adding S390 to the mailing list, I got the incorrect address in the initial
> patch.
> 
> Much appreciated if S390 people can give it a test.
> 
> Thanks,
> Qu
> 
> 在 2026/1/19 16:24, Qu Wenruo 写道:
> > [BUG]
> > After commit aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration
> > buffer preparation"), we no longer release the folio of the page cache
> > of folio returned by btrfs_compress_filemap_get_folio() for S390
> > hardware accerlation path.
> > 
> > [CAUSE]
> > Before that commit, we call kumap_local() and folio_put() after handling
> > each folio.
> > 
> > Although the timing is not ideal (it release previous folio at the
> > beginning of the loop, and rely on some extra cleanup out of the loop),
> > it at least handles the folio release correctly.
> > 
> > Meanwhile the refactored code is easier to read, it lacks the call to
> > release the filemap folio.
> > 
> > [FIX]
> > Add the missing folio_put() for copy_data_into_buffer().
> > 
> > Cc: linux-s390@vger.kernel.orgaa60fe12b4f49f49fc73e5023f8675e2df1f7805
> > Fixes: aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration buffer preparation")
> > Signed-off-by: Qu Wenruo <wqu@suse.com>
> > ---
> >   fs/btrfs/zlib.c | 1 +
> >   1 file changed, 1 insertion(+)
> > 
> > diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
> > index 6caba8be7c84..10ed48d4a846 100644
> > --- a/fs/btrfs/zlib.c
> > +++ b/fs/btrfs/zlib.c
> > @@ -139,6 +139,7 @@ static int copy_data_into_buffer(struct address_space *mapping,
> >   		data_in = kmap_local_folio(folio, offset);
> >   		memcpy(workspace->buf + cur - filepos, data_in, copy_length);
> >   		kunmap_local(data_in);
> > +		folio_put(folio);
> >   		cur += copy_length;
> >   	}
> >   	return 0;

Mikhail, can you have a look at this, please?

Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

[Mikhail Zaslonko]

Hello Qu,

Sorry for the late response. 
I ran some test on s390 including folio-leak verification. LGTM.

Tested-by:   Mikhail Zaslonko <zaslonko@linux.ibm.com>


On 20-Jan-26 23:52, Qu Wenruo wrote:
> Adding S390 to the mailing list, I got the incorrect address in the initial patch.
> 
> Much appreciated if S390 people can give it a test.
> 
> Thanks,
> Qu
> 
> 
> 在 2026/1/19 16:24, Qu Wenruo 写道:
>> [BUG]
>> After commit aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration
>> buffer preparation"), we no longer release the folio of the page cache
>> of folio returned by btrfs_compress_filemap_get_folio() for S390
>> hardware accerlation path.
>>
>> [CAUSE]
>> Before that commit, we call kumap_local() and folio_put() after handling
>> each folio.
>>
>> Although the timing is not ideal (it release previous folio at the
>> beginning of the loop, and rely on some extra cleanup out of the loop),
>> it at least handles the folio release correctly.
>>
>> Meanwhile the refactored code is easier to read, it lacks the call to
>> release the filemap folio.
>>
>> [FIX]
>> Add the missing folio_put() for copy_data_into_buffer().
>>
>> Cc: linux-s390@vger.kernel.orgaa60fe12b4f49f49fc73e5023f8675e2df1f7805
>> Fixes: aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration buffer preparation")
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>> ---
>>   fs/btrfs/zlib.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
>> index 6caba8be7c84..10ed48d4a846 100644
>> --- a/fs/btrfs/zlib.c
>> +++ b/fs/btrfs/zlib.c
>> @@ -139,6 +139,7 @@ static int copy_data_into_buffer(struct address_space *mapping,
>>           data_in = kmap_local_folio(folio, offset);
>>           memcpy(workspace->buf + cur - filepos, data_in, copy_length);
>>           kunmap_local(data_in);
>> +        folio_put(folio);
>>           cur += copy_length;
>>       }
>>       return 0;
> 
> 

Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

[David Sterba]

On Thu, Feb 05, 2026 at 11:54:21PM +0100, Mikhail Zaslonko wrote:
> Hello Qu,
> 
> Sorry for the late response. 
> I ran some test on s390 including folio-leak verification. LGTM.
> 
> Tested-by:   Mikhail Zaslonko <zaslonko@linux.ibm.com>

Thanks for testing, the patch has been merged to 6.19.

Re: [PATCH] btrfs: fix the folio leak on S390 hardware acceleration

[David Sterba]

On Mon, Jan 19, 2026 at 04:24:04PM +1030, Qu Wenruo wrote:
> [BUG]
> After commit aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration
> buffer preparation"), we no longer release the folio of the page cache
> of folio returned by btrfs_compress_filemap_get_folio() for S390
> hardware accerlation path.
> 
> [CAUSE]
> Before that commit, we call kumap_local() and folio_put() after handling
> each folio.
> 
> Although the timing is not ideal (it release previous folio at the
> beginning of the loop, and rely on some extra cleanup out of the loop),
> it at least handles the folio release correctly.
> 
> Meanwhile the refactored code is easier to read, it lacks the call to
> release the filemap folio.
> 
> [FIX]
> Add the missing folio_put() for copy_data_into_buffer().
> 
> Cc: linux-s390@vger.kernel.orgaa60fe12b4f49f49fc73e5023f8675e2df1f7805
> Fixes: aa60fe12b4f4 ("btrfs: zlib: refactor S390x HW acceleration buffer preparation")
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: David Sterba <dsterba@suse.com>