Re: [PATCH] block: Fix potential page reference leak in __bio_iov_iter_get_pages()

[linmiaohe]

Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>On Tue, Sep 01, 2020 at 08:00:06AM -0400, Miaohe Lin wrote:
>> When bio is full, __bio_iov_iter_get_pages() would return error 
>> directly while left page reference still held in pages. Release these references.
>> Also advance the iov_iter according to what we have done successfully.
>> 
>> Fixes: 576ed9135489 ("block: use bio_add_page in 
>> bio_iov_iter_get_pages")
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>
>The WARN_ON means something is fundamentally wrong here.  I think a few leaked pages are the least of our problems in this case.

Yes, WARN_ON means something is fundamentally wrong here. But IMO it's not really a big problem when bio is full.
We should not simply rely on this WARN_ON and we can handle this gracefully.
Thanks.