linux-kernel - Re: [PATCH] block: Fix dio_cleanup() to advance the head index

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Date:   Wed, 14 Jun 2023 09:28:36 +0200
From:   David Hildenbrand <david@...hat.com>
To:     David Howells <dhowells@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        kernel test robot <oliver.sang@...el.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz>,
        Jeff Layton <jlayton@...nel.org>,
        Jason Gunthorpe <jgg@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Hillf Danton <hdanton@...a.com>,
        Christian Brauner <brauner@...nel.org>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-mm@...ck.org, oe-lkp@...ts.linux.dev, lkp@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block: Fix dio_cleanup() to advance the head index

On 13.06.23 23:54, David Howells wrote:
>      
> Fix dio_bio_cleanup() to advance the head index into the list of pages past
> the pages it has released, as __blockdev_direct_IO() will call it twice if
> do_direct_IO() fails.
> 
> The issue was causing:
> 
>          WARNING: CPU: 6 PID: 2220 at mm/gup.c:76 try_get_folio
> 
> This can be triggered by setting up a clean pair of UDF filesystems on
> loopback devices and running the generic/451 xfstest with them as the
> scratch and test partitions.  Something like the following:
> 
>      fallocate /mnt2/udf_scratch -l 1G
>      fallocate /mnt2/udf_test -l 1G
>      mknod /dev/lo0 b 7 0
>      mknod /dev/lo1 b 7 1
>      losetup lo0 /mnt2/udf_scratch
>      losetup lo1 /mnt2/udf_test
>      mkfs -t udf /dev/lo0
>      mkfs -t udf /dev/lo1
>      cd xfstests
>      ./check generic/451
> 
> with xfstests configured by putting the following into local.config:
> 
>      export FSTYP=udf
>      export DISABLE_UDF_TEST=1
>      export TEST_DEV=/dev/lo1
>      export TEST_DIR=/xfstest.test
>      export SCRATCH_DEV=/dev/lo0
>      export SCRATCH_MNT=/xfstest.scratch
> 
> Fixes: 1ccf164ec866 ("block: Use iov_iter_extract_pages() and page pinning in direct-io.c")
> Reported-by: kernel test robot <oliver.sang@...el.com>
> Closes: https://lore.kernel.org/oe-lkp/202306120931.a9606b88-oliver.sang@intel.com
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: Christoph Hellwig <hch@...radead.org>
> cc: David Hildenbrand <david@...hat.com>
> cc: Andrew Morton <akpm@...ux-foundation.org>
> cc: Jens Axboe <axboe@...nel.dk>
> cc: Al Viro <viro@...iv.linux.org.uk>
> cc: Matthew Wilcox <willy@...radead.org>
> cc: Jan Kara <jack@...e.cz>
> cc: Jeff Layton <jlayton@...nel.org>
> cc: Jason Gunthorpe <jgg@...dia.com>
> cc: Logan Gunthorpe <logang@...tatee.com>
> cc: Hillf Danton <hdanton@...a.com>
> cc: Christian Brauner <brauner@...nel.org>
> cc: Linus Torvalds <torvalds@...ux-foundation.org>
> cc: linux-fsdevel@...r.kernel.org
> cc: linux-block@...r.kernel.org
> cc: linux-kernel@...r.kernel.org
> cc: linux-mm@...ck.org
> ---
>   fs/direct-io.c |    1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 0643f1bb4b59..2ceb378b93c0 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -459,6 +459,7 @@ static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)
>   	if (dio->is_pinned)
>   		unpin_user_pages(dio->pages + sdio->head,
>   				 sdio->tail - sdio->head);
> +	sdio->head = sdio->tail;
>   }
>   
>   /*
> 

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb