On Mon, Dec 14, 2020 at 9:03 AM Michal Hocko <mhocko@xxxxxxxx> wrote: > > On Fri 11-12-20 15:21:36, Pavel Tatashin wrote: > > PF_MEMALLOC_NOCMA is used ot guarantee that the allocator will not return > > pages that might belong to CMA region. This is currently used for long > > term gup to make sure that such pins are not going to be done on any CMA > > pages. > > > > When PF_MEMALLOC_NOCMA has been introduced we haven't realized that it is > > focusing on CMA pages too much and that there is larger class of pages that > > need the same treatment. MOVABLE zone cannot contain any long term pins as > > well so it makes sense to reuse and redefine this flag for that usecase as > > well. Rename the flag to PF_MEMALLOC_PIN which defines an allocation > > context which can only get pages suitable for long-term pins. > > > > Also re-name: > > memalloc_nocma_save()/memalloc_nocma_restore > > to > > memalloc_pin_save()/memalloc_pin_restore() > > and make the new functions common. > > > > Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> > > Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx> > > Acked-by: Michal Hocko <mhocko@xxxxxxxx> Thank you. > > with one comment below > [...] > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -1576,7 +1576,7 @@ extern struct pid *cad_pid; > > #define PF_SWAPWRITE 0x00800000 /* Allowed to write to swap */ > > #define PF_NO_SETAFFINITY 0x04000000 /* Userland is not allowed to meddle with cpus_mask */ > > #define PF_MCE_EARLY 0x08000000 /* Early kill for mce process policy */ > > -#define PF_MEMALLOC_NOCMA 0x10000000 /* All allocation request will have _GFP_MOVABLE cleared */ > > +#define PF_MEMALLOC_PIN 0x10000000 /* All allocation request will have _GFP_MOVABLE cleared */ > > This comment is not really helpeful. I would go with > /* Allocation context constrained to zones which allow long term > * pinning. > */ > > Something similar would be useful for memalloc_pin* functions as well. I will add it. > -- > Michal Hocko > SUSE Labs
