On Sun, May 26, 2013 at 11:30 AM, Rafael Aquini <aquini@xxxxxxxxxx> wrote: > On Sun, May 26, 2013 at 10:55:32AM -0400, KOSAKI Motohiro wrote: >> On Sun, May 26, 2013 at 9:52 AM, Rafael Aquini <aquini@xxxxxxxxxx> wrote: >> > On Sun, May 26, 2013 at 07:44:56AM -0400, KOSAKI Motohiro wrote: >> >> > + /* >> >> > + * By flagging sys_swapon, a sysadmin can tell us to >> >> > + * either do sinle-time area discards only, or to just >> >> > + * perform discards for released swap page-clusters. >> >> > + * Now it's time to adjust the p->flags accordingly. >> >> > + */ >> >> > + if (swap_flags & SWAP_FLAG_DISCARD_ONCE) >> >> > + p->flags &= ~SWP_PAGE_DISCARD; >> >> > + else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) >> >> > + p->flags &= ~SWP_AREA_DISCARD; >> >> >> >> When using old swapon(8), this code turn off both flags, right >> > >> > As the flag that enables swap discards SWAP_FLAG_DISCARD remains meaning the >> > same it meant before, when using old swapon(8) (SWP_PAGE_DISCARD|SWP_AREA_DISCARD) >> >> But old swapon(8) don't use neigher SWAP_FLAG_DISCARD_ONCE nor >> SWAP_FLAG_DISCARD_PAGES. It uses only SWAP_FLAG_DISCARD. So, this >> condition disables both SWP_PAGE_DISCARD and SWP_AREA_DISCARD. >> > > This condition _only_ disables one of the new flags orthogonally if swapon(8) > flags a policy to sys_swapon. As old swapon(8) can only flag SWAP_FLAG_DISCARD, > the original behavior is kept. Nothing will change when one is using an old > swapon(8) with this changeset. Aha, got it. I misunderstood your code. Thank you. Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> -- 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>