Re: [PATCH] userfaultfd: reset err when move_pages_ptes succeeded

On 26/08/15 09:13PM, Foxie Flakey wrote:
> 
> There is an edge case when move_pages_ptes fails with EAGAIN and then outer
> loop attempt to retry and succeeded but "err" isn't reset. This leads to
> outer loop retry erroneously on same set of pages that was successfully
> moved. This is fixed by resetting "err" when move_pages_ptes succeeded.
> 
> Fixes: 50944692052b ("userfaultfd: opportunistic TLB-flush batching for present pages in MOVE")
> Signed-off-by: Foxie Flakey <[email protected]>
> Assisted-by: ChatGPT:GPT-5.6-Luna
> ---
>  mm/userfaultfd.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index c3adedaaf7d5..595e7e232f90 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -2069,10 +2069,12 @@ static ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
>  			ret = move_pages_ptes(mm, dst_pmd, src_pmd,
>  					      dst_vma, src_vma, dst_addr,
>  					      src_addr, src_end - src_addr, mode);
> -			if (ret < 0)
> +			if (ret < 0) {
>  				err = ret;
> -			else
> +			} else {
> +				err = 0;
>  				step_size = ret;
> +			}
>  		}
> 
>  		cond_resched();
> 
> base-commit: 62cc90241548d5570ee68e01aaba6506964e9811
> -- 
> 2.55.0
> 
> 

Hi,

Use `./scripts/get_maintainer.pl <file>` to figure out to which mailing
list you should send your patches. Also don't forget to CC the subsytem
and the file maintainer. I don't think this is the correct mailing list
for your patch :)

Cheers,
    Ali