On Sun, May 13, 2007 at 10:46:30PM -0700, Andrew Morton wrote: > On Mon, 14 May 2007 10:37:18 +0800 Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote: > > > PG_lazyfree and PG_booked shares the same bit. > > > > Either it is a bug that shall fixed by the following patch, or > > the situation should be explicitly documented? > > > > Signed-off-by: Fengguang Wu <wfg@xxxxxxxxxxxxxxxx> > > --- > > include/linux/page-flags.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > --- linux-2.6.21-mm2.orig/include/linux/page-flags.h > > +++ linux-2.6.21-mm2/include/linux/page-flags.h > > @@ -91,7 +91,7 @@ > > #define PG_buddy 19 /* Page is free, on buddy lists */ > > #define PG_booked 20 /* Has blocks reserved on-disk */ > > > > -#define PG_lazyfree 20 /* MADV_FREE potential throwaway */ > > +#define PG_lazyfree 21 /* MADV_FREE potential throwaway */ > > > > /* PG_owner_priv_1 users should have descriptive aliases */ > > #define PG_checked PG_owner_priv_1 /* Used by some filesystems */ > > That's an accident: PG_lazyfree got added but the out-of-tree ext4 patches > didn't get updated. > > otoh, the intersection between pages which are PageBooked() and pages which > are PageLazyFree() should be zreo, so it'd be good to actually formalise > this reuse within the ext4 patches. > > otoh2, PageLazyFree() could have reused PG_owner_priv_1. otoh3: PG_lazyfree and PG_readahead can reuse the same bit, too. PG_lazyfree applies to anonymous pages, while PG_readahead applies to file backed pages. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
