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charset="us-ascii" Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 93DB8140017 X-Stat-Signature: aezk31cc6oekzktpmrnxhbp7eed3ihhu X-HE-Tag: 1789488132-247659 X-HE-Meta: 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 BmgupKea 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 11 Sep 2026 09:32:00 -0700 Andrew Morton wrote: > does any of this look real? The mechanism seems real, but it only shows up with vm.defrag_mode=1, which is off by default. With defrag_mode=1, a costly __GFP_NORETRY allocation that used to fail cleanly can now succeed by fragmenting another migratetype's pageblock, which seems like the wrong trade for a caller whose premise is a cheap lower-order fallback. Johannes, do we want to keep it strict? If so, we could add a condition like below. It is equally applicable to v4 and v5. Happy to send it separately or in v6. /* * Reclaim/compaction cannot run, so defrag_mode's strategy * of enforcing ALLOC_NOFRAGMENT cannot be fulfilled. Allow * fallbacks rather than failing the allocation outright. * Not for costly __GFP_NORETRY: those have a cheap lower * order fallback, so failing beats fragmenting. */ if (defrag_mode && (alloc_flags & ALLOC_NOFRAGMENT) && !(costly_order && (gfp_mask & __GFP_NORETRY)) && (gfp_mask & __GFP_KSWAPD_RECLAIM)) { alloc_flags &= ~ALLOC_NOFRAGMENT; goto retry; } Salvatore AMAZON DEVELOPMENT CENTER ITALY SRL, viale Monte Grappa 3/5, 20124 Milano, Italia, Registro delle Imprese di Milano Monza Brianza Lodi REA n. 2504859, Capitale Sociale: 10.000 EUR i.v., Cod. Fisc. e P.IVA 10100050961, Societa con Socio Unico