On Tue, 4 Feb 2014, Andrew Morton wrote: > > Commit bf6bddf1924e ("mm: introduce compaction and migration for ballooned > > pages") introduces page_count(page) into memory compaction which > > dereferences page->first_page if PageTail(page). > > > > Introduce a store memory barrier to ensure page->first_page is properly > > initialized so that code that does page_count(page) on pages off the lru > > always have a valid p->first_page. > > Could we have a code comment please? Even checkpatch knows this rule! > Ok. > > Reported-by: Holger Kiehl <Holger.Kiehl@xxxxxx> > > What did Holger report? > A once-in-five-years NULL pointer dereference on the aforementioned page_count(page). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>