On Wed, May 11, 2022 at 04:13:10PM -0700, John Hubbard wrote: > On 5/11/22 16:08, Minchan Kim wrote: > > > OK, so the code checks the wrong item each time. But the code really > > > only needs to know "is either _CMA or _ISOLATE set?". And so you > > > > Yes. > > > > > can just sidestep the entire question by writing it like this: > > > > > > int mt = get_pageblock_migratetype(page); > > > > > > if (mt & (MIGRATE_ISOLATE | MIGRATE_CMA)) > > > return false; > > > > I am confused. Isn't it same question? > > > > set_pageblock_migratetype(MIGRATE_ISOLATE) > > if (get_pageblock_migrate(page) & MIGRATE_CMA) > > > > set_pageblock_migratetype(MIGRATE_CMA) > > > > if (get_pageblock_migrate(page) & MIGRATE_ISOLATE) > > Well no, because the "&" operation is a single operation on the CPU, and > isn't going to get split up like that. Oh, if that's true, yeah, I could live with it. Thanks, let me post next revision with commenting about that.
