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AJvYcCVmxBbnHp1NhF8uTCkK6DpH1Jw0qbtsgpTcEYB1quiru3h+HxkzN5UfSzhIxmHIILEw4Ncacr/rew==@kvack.org X-Gm-Message-State: AOJu0Yz+3TWtvN1Ub5yTmusEnyg6OdIuu2U9uzSXbpO7YFkyDpddhYCf qKzi2br9+lxya3eHPW6Ak05mAXLPPpgEOCju/0SbZ2mRVkKGjQW8MptIoFab53t0AFiEJPdvoTo t4z5K9ww6aieE4A== X-Received: from wmlz10.prod.google.com ([2002:a05:600c:220a:b0:485:32b2:6b8d]) (user=jackmanb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:8b18:b0:485:3dfc:57d with SMTP id 5b1f17b1804b1-486ff01ca8dmr31517965e9.30.1774000093379; Fri, 20 Mar 2026 02:48:13 -0700 (PDT) Date: Fri, 20 Mar 2026 09:48:12 +0000 In-Reply-To: Mime-Version: 1.0 References: <20260319-gfp64-v1-0-2c73b8d42b7f@google.com> X-Mailer: aerc 0.21.0 Message-ID: Subject: Re: [PATCH 0/5] mm: Switch gfp_t to unsigned long From: Brendan Jackman To: Matthew Wilcox , Brendan Jackman , Cc: Andrew Morton , Michal Hocko , David Rientjes , Shakeel Butt , Vlastimil Babka , Suren Baghdasaryan , Johannes Weiner , Zi Yan , Harry Yoo , Hao Li , Christoph Lameter , Roman Gushchin , Uladzislau Rezki , , Content-Type: text/plain; charset="UTF-8" X-Rspam-User: X-Rspamd-Queue-Id: 31C9A4000B X-Rspamd-Server: rspam08 X-Stat-Signature: w7u8qht7nbfup9wb5k346m7gjp3pbgu1 X-HE-Tag: 1774000094-862494 X-HE-Meta: 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 OMwz0S9s 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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 Thu Mar 19, 2026 at 9:39 PM UTC, Matthew Wilcox wrote: > On Thu, Mar 19, 2026 at 06:40:59PM +0000, Brendan Jackman wrote: >> I will paste the diff at the bottom. I _think_ all the problematic >> expansions are downstream of struct xarray, but it's quite likely my >> sense for problematic struct expansions is weak. > > Urgh, no, it's not all xarray. There's one in address_space which we're > trying to shrink, not grow. Oh sorry I just assumed that one was xa_flags. > There's one in struct sock too. Huh, I suspect I am embarassing myself with this question, but why are we sensitive to the size of struct sock? It's currently 784 bytes in my build. Are the adjacent fields very hot, and we need to look up the GFP flags from hot paths? > I don't think this idea is worth it. There are other projects of greater > or lesser churniess which will give us some flags back. For example, > we could finish the GFP_NOFS and GFP_NOIO removal. We could finish the > radix_tree -> XArray removal and get back three bits. That's five bits > without even starting new projects, just finishing old ones. Anyway, this also makes sense. But, Vlastimil, I guess you had an ulterior motive for this suggestion?