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Wed, 23 Oct 2024 17:12:16 +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 EK1PM3AuGWcYSAAAD6G6ig (envelope-from ); Wed, 23 Oct 2024 17:12:16 +0000 Message-ID: Date: Wed, 23 Oct 2024 19:12:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] mm/slab: fix a memory leak on kobject_init_and_add() failure Content-Language: en-US From: Vlastimil Babka To: Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Christoph Lameter (Ampere)" Cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , linux-mm@kvack.org References: <20241021091413.154775-1-42.hyeyoo@gmail.com> <77d5c04b-9b97-4aee-85a9-c5efb2fa21fe@suse.cz> <439eed20-d0c7-8332-2f17-d785321d3310@gentwo.org> <059dead9-51c5-49b9-bbb9-5f3be741c830@suse.cz> <7e4978d7-7f93-5d30-bf2a-736b0e1e9ad4@gentwo.org> <200f4eb7-f367-4020-ad44-382e3a24ee2a@suse.cz> 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: <200f4eb7-f367-4020-ad44-382e3a24ee2a@suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: y74tgw1p1g73pzg8q4btgac334sa788s X-Rspamd-Queue-Id: 621DA14001B X-Rspamd-Server: rspam02 X-HE-Tag: 1729703527-398117 X-HE-Meta: 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 R2dzym/l 633kCMNBo3dT0cb0IO7Fev2Ud96/YKCi5HECvhyC3BQl2NpABSr/0JrsKRRWM1Dt9fPEdwiRpQI7jV118MB0TaLNv+ODINXqcEjtySPG4QPJ0QzFNPSESF5kaKIt3AUQj8eZW4UjEVL58KMzfscdr4d1C1G7u0IDU5Nehf6yIFgq3UGCvh9hHjxpEAeQgNH1TnKJPo0hGhR64gguCxE6xNt3ZUmRdvIPzDFLy30iXbTjaPup6kr9BHp2L0iqQBeL70N9DZ0X863p9lhJFEXroBXqFyik7SKGC9a4/TXftRRqUGB1M3+e5Raso5OIGBuHuHgoLT/BUzy7kLCyXBjRmUSGhXsVzVuXUlGGe8cB3rfIh9bIoGMY25SxB9PoATQ+IhDdfzOpK1AnWFJ67VhbY9T4bUOI6R0d6ZGCZOsYH7c24Qhawy7db+HqnqTFTGAkGLwmdHf+Hgf0ONIHWwsEcMYZLN2l7ZD34anJXXtb6xOCdAGw= 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 10/23/24 11:28, Vlastimil Babka wrote: > On 10/23/24 11:23, Hyeonggon Yoo wrote: >> On Wed, Oct 23, 2024 at 1:08 AM Christoph Lameter (Ampere) >> wrote: >>> >>> On Tue, 22 Oct 2024, Vlastimil Babka wrote: >>> >>> > On 10/21/24 18:27, Christoph Lameter (Ampere) wrote: >>> > > On Mon, 21 Oct 2024, Vlastimil Babka wrote: >>> > > >>> > >> I think the comment "If this function returns an error, kobject_put() must >>> > >> be called" means that *if* you want to destroy it due to the failure, you >>> > >> must use kobject_put() and not e.g. kfree(). But IMHO it doesn't mean you >>> > >> must destroy it because of the kobject_add() failure. >>> > > >>> > > Right. The simplest solution is to see the sysfs stuff as optional. If it >>> > >>> > To clarify, I only meant the case of boot caches processed for sysfs later. >>> > I don't think we need to start ignoring all sysfs errors. >>> >>> Well not ignoring. Write something to the syslog. So it wont affect slab >>> operations. /sys support is not critical to the slab subsystem operations >>> and is often not used at all. >>> >>> If its conks out then it should be fixed but it should not impact current >>> operations. We have had so many issues with sysfs support in the past that >>> doing so would be wise to avoid future problems. >> >> Both directions look fine to me. Christoph's approach would probably be better >> for maintainability I think? Failing to create sysfs files is not a >> critical problem anyway. > > Yeah I guess, if it makes things simpler... Feel free to do that as v2 then! However we should also make sure aliases (the symlinks) behave sanely and consistently. Now __kmem_cache_alias() will bail out if sysfs_slab_alias() fails, for example. To be consistent it should also just log the failure and proceed. And if the initial mergeable cache fails to create its "unique name" that aliases symlink to, then all the symlink attempts probably will also either fail or point to a nonexisting directory. Probably can't be helped, just make sure it behaves consistently?