linux-kernel - Re: [PATCH] media: atomisp: Fixed error handling path

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Message-ID: <20200928083757.GA18329@kadam>
Date:   Mon, 28 Sep 2020 11:37:57 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Souptick Joarder <jrdr.linux@...il.com>
Cc:     mchehab@...nel.org, sakari.ailus@...ux.intel.com,
        gregkh@...uxfoundation.org, daniel.m.jordan@...cle.com,
        akpm@...ux-foundation.org, walken@...gle.com,
        gustavoars@...nel.org, linux-media@...r.kernel.org,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        John Hubbard <jhubbard@...dia.com>,
        Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH] media: atomisp: Fixed error handling path

On Sun, Sep 27, 2020 at 08:38:04PM +0530, Souptick Joarder wrote:
> Inside alloc_user_pages() based on flag value either pin_user_pages()
> or get_user_pages_fast() will be called. However, these API might fail.
> 
> But free_user_pages() called in error handling path doesn't bother
> about return value and will try to unpin bo->pgnr pages, which is
> incorrect.
> 
> Fix this by passing the page_nr to free_user_pages(). If page_nr > 0
> pages will be unpinned based on bo->mem_type. This will also take care
> of non error handling path.
> 
> Fixes: 14a638ab96c5 ("media: atomisp: use pin_user_pages() for memory
> allocation")
> Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
> Cc: John Hubbard <jhubbard@...dia.com>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Cc: Dan Carpenter <dan.carpenter@...cle.com>
> ---
>  drivers/staging/media/atomisp/pci/hmm/hmm_bo.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/media/atomisp/pci/hmm/hmm_bo.c b/drivers/staging/media/atomisp/pci/hmm/hmm_bo.c
> index f13af23..0168f98 100644
> --- a/drivers/staging/media/atomisp/pci/hmm/hmm_bo.c
> +++ b/drivers/staging/media/atomisp/pci/hmm/hmm_bo.c
> @@ -857,16 +857,17 @@ static void free_private_pages(struct hmm_buffer_object *bo,
>  	kfree(bo->page_obj);
>  }
>  
> -static void free_user_pages(struct hmm_buffer_object *bo)
> +static void free_user_pages(struct hmm_buffer_object *bo,
> +			    unsigned int page_nr)
>  {
>  	int i;
>  
>  	hmm_mem_stat.usr_size -= bo->pgnr;
                              ^^^^^^^^^^^
This is still a problem.  It needs to be hmm_mem_stat.usr_size -= page_nr.

regards,
dan carpenter

>  
>  	if (bo->mem_type == HMM_BO_MEM_TYPE_PFN) {
> -		unpin_user_pages(bo->pages, bo->pgnr);
> +		unpin_user_pages(bo->pages, page_nr);
>  	} else {
> -		for (i = 0; i < bo->pgnr; i++)
> +		for (i = 0; i < page_nr; i++)
>  			put_page(bo->pages[i]);
>  	}
>  	kfree(bo->pages);