On 3/21/23 10:30, chenjun (AM) wrote: > 在 2023/3/20 17:12, Mike Rapoport 写道: >>>> >>>> If we ignore __GFP_ZERO passed by kzalloc， kzalloc will not work. >>>> Could we just unmask __GFP_RECLAIMABLE | __GFP_RECLAIM? >>>> >>>> pc.flags &= ~(__GFP_RECLAIMABLE | __GFP_RECLAIM) >>>> pc.flags |= __GFP_THISNODE >>> >>> __GFP_RECLAIMABLE would be wrong, but also ignored as new_slab() does: >>> flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK) >>> >>> which would filter out __GFP_ZERO as well. That's not a problem as kzalloc() >>> will zero out the individual allocated objects, so it doesn't matter if we >>> don't zero out the whole slab page. >>> >>> But I wonder, if we're not past due time for a helper e.g. >>> gfp_opportunistic(flags) that would turn any allocation flags to a >>> GFP_NOWAIT while keeping the rest of relevant flags intact, and thus there >>> would be one canonical way to do it - I'm sure there's a number of places >>> with their own variants now? >>> With such helper we'd just add __GFP_THISNODE to the result here as that's >>> specific to this particular opportunistic allocation. >> >> I like the idea, but maybe gfp_no_reclaim() would be clearer? >> > > #define gfp_no_reclaim(gfpflag) (gfpflag & ~__GFP_DIRECT_RECLAIM) I hoped for more feedback on the idea, but it's probably best proposed outside of this slub-specific thread, so we could go for an open-coded solution in slub for now. Also just masking out __GFP_DIRECT_RECLAIM wouldn't be sufficient in any case for the general solution/ > And here, > > pc.flags = gfp_no_reclaim(gfpflags) | __GFP_THISNODE. I'd still suggest as earlier: pc.flags = GFP_NOWAIT | __GFP_NOWARN |__GFP_THISNODE; > Do I get it right？
