On Mon 24-04-23 18:46:40, Baolin Wang wrote: > > > On 4/24/2023 5:50 PM, Michal Hocko wrote: > > On Sun 23-04-23 18:59:10, Baolin Wang wrote: > > > We've already used pfn_to_online_page() for start pfn to make sure > > > > Who is we? I do not see any note explicitly requiring that start_pfn has > > to be valid for __pageblock_pfn_to_page. > > Sorry for confusing, what I mean is the __pageblock_pfn_to_page() function, > which has used pfn_to_online_page() for start pfn. So the pfn_valid() in > __pageblock_pfn_to_page() for start pfn is unnecessary. > > I will update the commit log to make it clear. Your comment suggested that the check _has_ already been done. Which is not the case. pfn_to_online_page is called later in the function so I guess you should rephrase as following: " __pageblock_pfn_to_page currently performs both pfn_valid check and pfn_to_online_page. The former one is redundant because the latter is a stronger check. Drop pfn_valid. " With that or something going along with that. Feel free to add Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > > it is online and valid, so the pfn_valid() for the start pfn is > > > unnecessary, drop it. > > > > > > Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> > > > Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> > > > Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx> > > > --- > > > Changes from v1: > > > - Collect reviewed tags. Thanks David and Ying. > > > --- > > > mm/page_alloc.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > index 9de2a18519a1..6457b64fe562 100644 > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -1512,7 +1512,7 @@ struct page *__pageblock_pfn_to_page(unsigned long start_pfn, > > > /* end_pfn is one past the range we are checking */ > > > end_pfn--; > > > - if (!pfn_valid(start_pfn) || !pfn_valid(end_pfn)) > > > + if (!pfn_valid(end_pfn)) > > > return NULL; > > > start_page = pfn_to_online_page(start_pfn); > > > -- > > > 2.27.0 > > -- Michal Hocko SUSE Labs
