Messages in this thread | | | Subject | Re: [PATCH] mm: Unsigned 'nr_pages' always larger than zero | From | Vlastimil Babka <> | Date | Wed, 4 Sep 2019 13:24:58 +0200 |
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On 9/4/19 12:26 PM, zhong jiang wrote: > With the help of unsigned_lesser_than_zero.cocci. Unsigned 'nr_pages"' > compare with zero. And __get_user_pages_locked will return an long value. > Hence, Convert the long to compare with zero is feasible.
It would be nicer if the parameter nr_pages was long again instead of unsigned long (note there are two variants of the function, so both should be changed).
> Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Fixes: 932f4a630a69 ("mm/gup: replace get_user_pages_longterm() with FOLL_LONGTERM")
(which changed long to unsigned long)
AFAICS... stable shouldn't be needed as the only "risk" is that we goto check_again even when we fail, which should be harmless.
Vlastimil
> --- > mm/gup.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 23a9f9c..956d5a1 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1508,7 +1508,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk, > pages, vmas, NULL, > gup_flags); > > - if ((nr_pages > 0) && migrate_allow) { > + if (((long)nr_pages > 0) && migrate_allow) { > drain_allow = true; > goto check_again; > } >
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