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b=ES0zvciaohK0J9+7RmpXYjxpFv7LJFkSQIuMXxwQq8Fi5yRl1UkDmApnSBn553hSF +tubvcCgI4Z24G/XvGoPi5Q6XubUAuvumyNyf6Oi1cIKeyfAemPWH7ZLaugspv+HCr oxs6viXmtcxe3aP2U8mNykHgORNy/XdZLPA5ZZea9wk338T4ZGJuoUq3FjMY/BY865 ScNXtQAvn6n8kK3RGk5oc/v0nq293LYsMmBynLr8+9ymIQ0sTzy55ZkT+jkE6ms85c NmBVz6PrZemA+tHQGrJ+yQvRCUbzKlUc9IO1Ib0JEyuyDTxZ+11wiCZ+ZITS/UCJuK xQSW//hBZGheA== Message-ID: <96d3c629-6c03-4924-97b2-565a04c5861d@kernel.org> Date: Thu, 24 Sep 2026 09:41:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] slab: Remove slab_folio() Content-Language: en-US To: Matthew Wilcox Cc: Harry Yoo , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org References: <20260923183655.3364885-1-willy@infradead.org> <9bbdcace-0769-4391-9c97-e18e8a0fd207@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: agn1izi549tgxzqx43gn4j749798fa77 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 0AD6720007 X-HE-Tag: 1790235722-440843 X-HE-Meta: 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 uvZ2Mmjm Ckg12JvvRFxAi55Wv5gWiedOTJH6g2aYZFnGTZrntlKa5Wg9I9n2Lyv9ziZ/sHHGx5jZbzGThYEXyaOZRkGyS6a+AkHM/p6eygEF7kYx7zlYggsdI8kpuI+BX8Wrzlinbkh5HKtXVROOcuPtdw4nstg+wRquGlwMmlWPYdhBvc4K/ff60BC2G/i+3Q8eLzas2CLecXQd1jdxbGe8k9RpVLqsOLZeE8KDI4Ij+mg8ouqlDalqneKXRzAITVUu30rxI0lT05GILQHlVNvZk4SRTS+OvrcBCp6BEzY9gPjVyAJwqzDKTf4pOQ6RYxw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/23/26 22:41, Matthew Wilcox wrote: > On Wed, Sep 23, 2026 at 10:11:06PM +0200, Vlastimil Babka (SUSE) wrote: >> On 9/23/26 21:45, Harry Yoo wrote: >> > With a tiny little nit: >> > >> >> @@ -184,15 +169,16 @@ static inline struct slab *page_slab(const struct page *page) >> >> * slab_page - The first struct page allocated for a slab >> >> * @s: The slab. >> >> * >> >> - * A convenience wrapper for converting slab to the first struct page of the >> >> - * underlying folio, to communicate with code not yet converted to folio or >> >> - * struct slab. >> >> + * A convenience wrapper for returning the first page allocated to this slab. >> >> + * to communicate with code not yet converted to struct slab. >> > * A convenience wrapper for returning the first "struct" page allocated to this >> > * "slab" to communicate with code not yet converted to struct slab. >> >> */ >> > >> > Perhaps you meant this? > > My eyes are old and don't notice punctuation as well as they used to. > What I meant was: > > * A convenience wrapper for returning the first page allocated to this slab. > * This is for the benefit of code not yet converted to struct slab. > >> Yeah, and I wonder about the "code not yet converted" part, and if there's >> anything we can still convert right now. What I can see among slab_page() users: >> >> - slab_order() - we could probably add order (aliasing page's order for now) >> to struct slab right now and that would be future-proof > > That's trickier than you think because it's stored in the ->flags of > the second page when PG_head is set. When divorcing slab and page, > it moves into struct slab, but we can't do that in advance. Ah, I see. >> But: >> - slab_address() - I guess can only be converted once slab is divorced from >> page? > > Yeah, it becomes slab->virtual. > >> - __kasan_poison_slab - same as above? > > The loop calling page_kasan_tag_reset() makes me think kasan really > wants a page here. > >> - several VM_BUG_ON_PAGE() usages - same? > > We could probably introduce a VM_BUG_ON_SLAB if you're interested. Maybe not worth the effort. >> - validate_slab_ptr() - same? > > That'll change dramatically -- if we want to validate that a pointer > really points to a slab object, we'll want to, er, ask if > virt_to_slab() belongs to the slab slab. > >> __free_slab() - same, obviously > > Right.