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Howlett" , "Vlastimil Babka" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , , "Brendan Jackman" , "Johannes Weiner" , Subject: Re: [PATCH v2 1/1] mm: reduce NODE_RECLAIM_xxx and change to enum X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Brendan Jackman" To: "Zi Yan" , "Brendan Jackman" References: <20260612085052.59291-1-ptesarik@suse.com> <20260612133155.71958e80@mordecai> <34223C0D-B52D-41D4-AACC-943A4BEB3472@nvidia.com> In-Reply-To: <34223C0D-B52D-41D4-AACC-943A4BEB3472@nvidia.com> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: A092340005 X-Stat-Signature: zptxb7pohb9refkc8ngu8efcact8o4y6 X-HE-Tag: 1781277030-410368 X-HE-Meta: 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 Ammxk4sm pKKpfr0whsrZ3+vRy0n+qkC/k57F/ymCcY9/vYNRD7FmuMouFIOL4YIfKnDJ7+uPYllwqO8uZo9f6hGpX8Kr//r5n+9j1fDwS7HYhg/VamdsvRFcLupExNE0JuWrZvguCqOl7CWHx8C/0Cjef8s5N/yLn3vAWgONFyxFYFIicKordTaoLNXvDNbHkHV7fmKBQWn9ahLtakyJ3VG3HcsZ5QAvQz/+fC2TiQ/swy6v1k1Sh+w5Cue9m2d4dta7I5gmTBMO8cTKrU8hBSX9EU8faY+IcDBRcBHHyMoL2 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri Jun 12, 2026 at 3:01 PM UTC, Zi Yan wrote: > On 12 Jun 2026, at 10:28, Brendan Jackman wrote: > >> On Fri Jun 12, 2026 at 11:31 AM UTC, Petr Tesarik wrote: >>>>> >>>>> - NODE_RECLAIM_NOSCAN -> NODE_RECLAIM_NONE >>>>> - NODE_RECLAIM_FULL -> NODE_RECLAIM_NONE >>>>> - NODE_RECLAIM_SOME -> NODE_RECLAIM_SUCCESS >>>>> - NODE_RECLAIM_SUCCESS -> NODE_RECLAIM_SUCCESS >> >>>>> --- a/mm/internal.h >>>>> +++ b/mm/internal.h >>>>> @@ -1373,23 +1373,24 @@ static inline void mminit_verify_zonelist(voi= d) >>>>> } >>>>> #endif /* CONFIG_DEBUG_MEMORY_INIT */ >>>>> >>>>> -#define NODE_RECLAIM_NOSCAN -2 >>>>> -#define NODE_RECLAIM_FULL -1 >>>>> -#define NODE_RECLAIM_SOME 0 >>>>> -#define NODE_RECLAIM_SUCCESS 1 >>>>> +enum node_reclaim { >>>>> + NODE_RECLAIM_NONE, >>>>> + NODE_RECLAIM_SUCCESS, >>>>> +}; >> >>>>> - ret =3D __node_reclaim(pgdat, gfp_mask, nr_pages, &sc) >=3D nr_page= s; >>>>> + nr_reclaimed =3D __node_reclaim(pgdat, gfp_mask, nr_pages, &sc); >>>>> clear_bit_unlock(PGDAT_RECLAIM_LOCKED, &pgdat->flags); >>>>> >>>>> - if (ret) >>>>> + if (nr_reclaimed >=3D nr_pages) >>>>> count_vm_event(PGSCAN_ZONE_RECLAIM_SUCCESS); >>>>> else >>>>> count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED); >>>>> >>>>> - return ret; >>>>> + return NODE_RECLAIM_SUCCESS; >>>> >>>> Should that be returning NODE_RECLAIM_NONE when !ret? >>> >>> No. That's the thing. Before my patch, the return value here was either >>> NODE_RECLAIM_SUCCESS (when at least nr_pages were reclaimed), or >>> NODE_RECLAIM_SOME (if less than nr_pages were reclaimed), but the calle= r >>> makes no distinction, handling both cases in the default label of a >>> switch statement. >> >> Agh! Sorry. It's good that you are cleaning this up :D >> >> So in that case my question is: is it intended that we call >> zone_watermark_ok() in the case that we reclaimed 0 pages? > > It seems to me that zone_watermark_ok() here is trying to > confirm the number of reclaimed pages is enough for the > allocation, although the return value of __node_reclaim() > might be able to tell the same thing like you suggested. > But nr_reclaimed >=3D nr_pages might not be equivalent > to zone_watermark_ok(). Yeah but in the more specific case of nr_reclaimed =3D=3D 0, would it make sense to assume !zone_watermark_ok()? It doesn't seem that important in terms of behaviour but I think it would be a clarity win.