On 08/07/20 at 10:28pm, Wei Yang wrote: > On Fri, Aug 07, 2020 at 08:49:51PM +0800, Baoquan He wrote: > >On 08/07/20 at 05:12pm, Wei Yang wrote: > >> list_first_entry() may not return NULL even when the list is empty. > >> > >> Let's make sure the behavior by using list_first_entry_or_null(), > >> otherwise it would corrupt the list. > >> > >> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> > >> --- > >> mm/hugetlb.c | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c > >> index 62ec74f6d03f..0a2f3851b828 100644 > >> --- a/mm/hugetlb.c > >> +++ b/mm/hugetlb.c > >> @@ -237,7 +237,8 @@ get_file_region_entry_from_cache(struct resv_map *resv, long from, long to) > >> VM_BUG_ON(resv->region_cache_count <= 0); > > > > > >We have had above line, is it possible to be NULL from list_first_entry? > > > >> > >> resv->region_cache_count--; > >> - nrg = list_first_entry(&resv->region_cache, struct file_region, link); > >> + nrg = list_first_entry_or_null(&resv->region_cache, > >> + struct file_region, link); > >> VM_BUG_ON(!nrg); > > Or we can remove this VM_BUG_ON()? Yeah, it's fine to me. > > >> list_del(&nrg->link); > >> > >> -- > >> 2.20.1 (Apple Git-117) > >> > >> > > -- > Wei Yang > Help you, Help me >
