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SubjectRe: [PATCH 4/4] fsfreeze: avoid to return zero in __get_user_pages
On Sat, Apr 6, 2013 at 6:07 AM, Marco Stornelli
<marco.stornelli@gmail.com> wrote:
> In case of VM_FAULT_RETRY, __get_user_pages returns the number
> of pages alredy gotten, but there isn't a check if this number is
> zero. Instead, we have to return a proper error code so we can avoid
> a possible extra call of __get_user_pages. There are several
> places where get_user_pages is called inside a loop until all the
> pages requested are gotten or an error code is returned.
>
> Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com>
> ---
> mm/memory.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 494526a..cca14ed 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1858,7 +1858,7 @@ long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> if (ret & VM_FAULT_RETRY) {
> if (nonblocking)
> *nonblocking = 0;
> - return i;
> + return i ? i : -ERESTARTSYS;

nonblock argument is only used from __mm_populate() and it expect
__get_user_pages() return 0.


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