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Mon, 9 Sep 2024 07:59:18 +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 WI/4D9aq3mZAZgAAD6G6ig (envelope-from ); Mon, 09 Sep 2024 07:59:18 +0000 Message-ID: Date: Mon, 9 Sep 2024 09:59:17 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] memcg: add charging of already allocated slab objects Content-Language: en-US To: Yosry Ahmed Cc: Shakeel Butt , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , David Rientjes , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Meta kernel team , cgroups@vger.kernel.org, netdev@vger.kernel.org References: <20240905173422.1565480-1-shakeel.butt@linux.dev> <572688a7-8719-4f94-a5cd-e726486c757d@suse.cz> 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-Server: rspam06 X-Rspamd-Queue-Id: 4B595A0002 X-Stat-Signature: tt1g3tkmficupmufjyk9km95awrwajgq X-Rspam-User: X-HE-Tag: 1725868760-485436 X-HE-Meta: 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 5Wb3y0hE kSvR58eB4z9I1Jwp6jLbmo6/9+YnZVw6aN0J0SNc3v0xy0l2LmmFF56T8jvbH611JGAz1X20rs0ZBrmushJS3cctdHQ4wuPw4+HT1EbxwL9tqTUM1pGKEOvjLvGJ6uBl4T+HArYMXOhdya37aQ30UBNsYMHUX4GJToNp9yLsjtdBMqrBe+8+C44OXizwWR3Up7G8ozblYl1M3/RCiauJyRfuTkjDoUOf+1CQNJ++pEKNIPn0pRCCRgPm1vHxKyVnthK98ymoANIuA9Zrs3Kk74iKraEpZPqBlxlmjvl6I4Hd8x9RQExR8gmcuANj9FkoachISK7hgHIhYH2caqfbydkP1UCiJJPJ0zv4Ad7pG5nim6n0= 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 9/6/24 19:38, Yosry Ahmed wrote: >> But in case of kmalloc() the allocation must have been still attempted with >> __GFP_ACCOUNT so a kmalloc-cg cache is used even if the charging fails. > > It is still possible that the initial allocation did not have > __GFP_ACCOUNT, but not from a KMALLOC_NORMAL cache (e.g. KMALLOC_DMA > or KMALLOC_RECLAIM). In this case kmem_cache_charge() should still > work, right? Yeah it would work, but that's rather a corner case implementation detail so it's better to just require __GFP_ACCOUNT for kmalloc() in the comment. >> >> If there's another usage for kmem_cache_charge() where the memcg is >> available but we don't want to charge immediately on purpose (such as the >> Linus' idea for struct file), we might need to find another way to tell >> kmalloc() to use the kmalloc-cg cache but not charge immediately... > > Can we just use a dedicated kmem_cache for this instead? Right, as Shakeel mentioned, that would be the case of struct file. If all such cases in the future are fine with dedicated cache (i.e. not variable sized allocations), it should be fine.