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Wed, 4 Dec 2024 16:07:01 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id kzTXDiV+UGfMagAAD6G6ig (envelope-from ); Wed, 04 Dec 2024 16:07:01 +0000 Message-ID: <839ce57b-c8be-4d78-8589-f2ee1ea91d28@suse.cz> Date: Wed, 4 Dec 2024 17:07:01 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 00/15] Allocate and free frozen pages Content-Language: en-US To: Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Matthew Wilcox (Oracle)" Cc: Andrew Morton , linux-mm@kvack.org, David Hildenbrand References: <20241125210149.2976098-1-willy@infradead.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; 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 BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Action: no action X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 1E8CD1A0011 X-Stat-Signature: stoymxgwhghb47tw5o9k464xqd74czni X-Rspam-User: X-HE-Tag: 1733328406-949055 X-HE-Meta: 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 Q/W/ACmN VVHKcfrxvX6T5osDndy86SB1TlmGtVwvXM0aiciV8GtNWW0ux8M9kvlO8F1VynwGVp6KZJvIbw3Wivrutfb+WXy4s4xbzb6W2f9aDBHAj4wN7VrNcccFp05MKpShogJ3C0+i7aGsvWMuXkxH0mtWqjDm4YEjjhPFYnZ9S0j7FOpxVvB8/bAatS/tF5qHevPsIjSwxOkdyasa4me62lW+im2n1hB+yMgLb93L2GKTUHVTkt/PrDj1RIVIfcw4UOcOBB4VeLy6TLn4TxKM+3ykDryifgOpC0+PMkzmQot84EErOg5P2buaSRDDVb2eSP4Z/vAsC83vdsidzwQdXcHuSX04Nn9htKhaJE2esIqjoIWIDqH3Q2aMFkD66U6hk9hfzsezJNXOPL6YCKXSfJfbjIsLXcriFeFp68K15cft3xHYwYhmrMOMmHFJfY1chPRuCgI8Y4YbXppQl8JQAcWdDozPDgQ== 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 11/26/24 06:04, Hyeonggon Yoo wrote: > On Tue, Nov 26, 2024 at 7:38 AM Matthew Wilcox (Oracle) > wrote: >> >> Slab does not need to use the page refcount at all, and it can avoid >> an atomic operation on page free. Hugetlb wants to delay setting the >> refcount until it has assembled a complete gigantic page. We already >> have the ability to freeze a page (safely reduce its reference count to >> 0), so this patchset adds APIs to allocate and free pages which are in >> a frozen state. > > [+Cc Vlastimil] > > I think with this patchset, we can finally remove the memory barriers used > in isolate_movable_page(), alloc_slab_page(), and __free_slab(), > because folio_get_nontail_page() should fail for frozen pages? Thanks for the heads-up! > for reference, the patch that introduced the memory barrier: > https://lore.kernel.org/linux-mm/Y20BRJmRzRVMzoJw@hyeyoo Are you going to sent the necessary patch on top of this series then? :) We could route it via -mm to avoid waiting a cycle or needing extra synchronization. It's not a pure slab change anyway... Thanks, Vlastimil > Best, > Hyeonggon