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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1u7ehY-00000009qzH-3LfM; Wed, 23 Apr 2025 18:20:05 +0000 Date: Wed, 23 Apr 2025 19:20:04 +0100 From: Matthew Wilcox To: Vlastimil Babka Cc: linux-mm@kvack.org, Harry Yoo , David Rientjes , Christoph Lameter , Andrew Morton Subject: Re: [PATCH RFC] mm, slab: warn when increasing refcount on large kmalloc page Message-ID: References: <20250417074102.4543-2-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250417074102.4543-2-vbabka@suse.cz> X-Rspam-User: X-Rspamd-Queue-Id: A3C5A180005 X-Rspamd-Server: rspam04 X-Stat-Signature: 8wogseecsjirf7nejmse4s5o56s5rjcg X-HE-Tag: 1745432409-264460 X-HE-Meta: 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 g6VY8BQY M7HvDZJQfJia/1kYz92dGP3IfmQXSviICYLIuNZLiYtQn2ObJfe+am8my3phkZvQjv5rWgsVJH7ipda6AECGwdzFQEcGkZ5pRA/d+MGYnV97UOWcy8p3TPHfUZVuO89mhKwO8Qj2ekhFcp3EsD2h6Ov6JT8HskhVHDCsg88jRLIQo6eJr48CU07dLA6TyzEdYHtkYcZlxbdX1ubO9Be6bEN3LUKcLWkUoSwma X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 17, 2025 at 09:41:03AM +0200, Vlastimil Babka wrote: > I'd like to expose this via slab-next and see if there are any reports. > If not for few weeks, maybe proceed immediately to freezing refcount and > handling it in get_page/put_page exactly like folio_test_slab. Thoughts? I think you're being too cautious ;-) I had a bit of a play around to see if there's a way of getting gcc to optimise the generated code for this, but didn't come up with anything too clever.