On Tue 07-01-20 09:22:41, Wei Yang wrote: > On Mon, Jan 06, 2020 at 11:23:45AM +0100, Michal Hocko wrote: > >On Fri 03-01-20 22:34:07, Wei Yang wrote: > >> As all the other places, we grab the lock before manipulate the defer list. > >> Current implementation may face a race condition. > > > >Please always make sure to describe the effect of the change. Why a racy > >list_empty check matters? > > > > Hmm... access the list without proper lock leads to many bad behaviors. My point is that the changelog should describe that bad behavior. > For example, if we grab the lock after checking list_empty, the page may > already be removed from list in split_huge_page_list. And then list_del_init > would trigger bug. And how does list_empty check under the lock guarantee that the page is on the deferred list? -- Michal Hocko SUSE Labs
