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Wed, 4 Dec 2024 08:54:54 +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 gfnvNN4YUGf8YQAAD6G6ig (envelope-from ); Wed, 04 Dec 2024 08:54:54 +0000 Message-ID: Date: Wed, 4 Dec 2024 09:54:54 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RESEND v2 4/6] mm/page_alloc: sort out the alloc_contig_range() gfp flags mess To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Andrew Morton , Oscar Salvador , Zi Yan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Naveen N Rao , Madhavan Srinivasan References: <20241203094732.200195-1-david@redhat.com> <20241203094732.200195-5-david@redhat.com> <96c92857-4850-4f85-9474-ac193c5ea48c@redhat.com> <04c1d28e-bbea-4499-9a6d-770f9ca53ba9@suse.cz> Content-Language: en-US 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: 7bit X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Queue-Id: 0D5ED40003 X-Rspamd-Server: rspam12 X-Stat-Signature: dfernqucs33py9kyhnsxmajwdxs4as1q X-Rspam-User: X-HE-Tag: 1733302482-804988 X-HE-Meta: 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 Ljc6eOI4 NcwhmCUw2krIjibHKXRZkUGn8ofBX90IrCud1Aw5JOrp7xNTW7vaCMapO3HOxV656k0aP7n/hxc9Q8kpnWSFcPzbueYDjVWmL63osiqxb0XIbXUN99Q8CgU3UPWAJx2BHb0+/A4Z6d/4VGbNf/RonHDu6OXu1qIEyTtQJI9dcWT6l8cPIY5KHtTHkz/MmW6LcU8M86bab/5yJGu4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000007, 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 12/3/24 20:19, David Hildenbrand wrote: > On 03.12.24 15:24, Vlastimil Babka wrote: >> On 12/3/24 15:12, David Hildenbrand wrote: >>> On 03.12.24 14:55, Vlastimil Babka wrote: >>> likely the thing we are assuming here is that we are migrating a page, and >>> usually, these are user allocation (except maybe balloon and some other non-lru >>> movable things). >> >> Yeah and user allocations obey cpuset and mempolicies etc. But these are >> likely somebody elses allocations that were done according to their >> policies. With our migration we might be actually violating those, which >> probably can't be helped (is at least migration within the same node >> preferred? hmm). > > I would hope that we handle memory policies somehow (via VMAs? not > sure). cpuset? I have no idea. They are handled when allocating, but then the info is lost, the allocation doesn't carry its effective nodemask. But that's really a separate issue that just occured to me. > But it doesn't seem to me that our caller's restrictions >> (if those exist, would be enforced by __GFP_HARDWALL) are that relevant for >> somebody else's pages? > > It was always set using "GFP_USER | __GFP_MOVABLE | > __GFP_RETRY_MAYFAIL", and I removed the same flag combination in #2 from > memory offline code, and we do have the exact same thing in > do_migrate_range() in mm/memory_hotplug.c. Yeah I agree a refactoring patch shouldn't change the existing behavior... > We should investigate if__GFP_HARDWALL is the right thing to use here, > and if we can get rid of that by switching to GFP_KERNEL in all these > places. > > I can look into it + send a follow-up patch. ...but it's a great opportunity to start questioning it and possibly change it as a follow up :) Thanks! > Thanks! >