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()? >> list_del(&nrg->link); >> >> -- >> 2.20.1 (Apple Git-117) >> >> -- Wei Yang Help you, Help me
