[{"id":3682282,"web_url":"http://patchwork.ozlabs.org/comment/3682282/","msgid":"<248dffc5-06ff-f9c2-7e39-c1ab991d2a16@ssi.bg>","list_archive_url":null,"date":"2026-04-25T14:40:07","subject":"Re: [PATCHv4 net] ipvs: fix races around est_mutex and est_cpulist","submitter":{"id":2825,"url":"http://patchwork.ozlabs.org/api/people/2825/","name":"Julian Anastasov","email":"ja@ssi.bg"},"content":"Hello,\n\nOn Sat, 25 Apr 2026, Julian Anastasov wrote:\n\n> Sashiko reports for races and possible crash around\n> the usage of est_cpulist_valid and sysctl_est_cpulist.\n> The problem is that we do not lock est_mutex in some\n> places which can lead to wrong write ordering and\n> as result problems when calling cpumask_weight()\n> and cpumask_empty().\n> \n> Fix them by moving the est_max_threads read/write under\n> locked est_mutex. Do the same for one ip_vs_est_reload_start()\n> call to protect the cpumask_empty() usage of sysctl_est_cpulist.\n> \n> To remove the chance of deadlock while stopping the\n> estimation kthreads, keep the data structure for kthread 0\n> even after last estimator is removed and do not hold mutexes\n> while stopping this task. Now we will use a new flag 'needed'\n> to know when kthread 0 should run. The kthreads above 0\n> do not use mutexes, so stop them under est_mutex because\n> their kthread data still can be destroyed if they do not\n> serve estimators. Now all kthreads will be started by\n> the est_reload_work to properly serialize the stop/start\n> for kthread 0.\n> \n> Reduce the use of service_mutex in ip_vs_est_calc_phase()\n> because under est_mutex we can safely walk est_kt_arr to\n> stop the kthreads above slot 0.\n> \n> Finally, fix use-after-free for kd->est_row in\n> ip_vs_est_calc_phase(). est->ktrow should simply switch to\n> a delay value while estimator is linked to est_temp_list.\n> \n> Link: https://sashiko.dev/#/patchset/20260331165015.2777765-1-longman%40redhat.com\n> Link: https://sashiko.dev/#/patchset/20260420171308.87192-1-ja%40ssi.bg\n> Link: https://sashiko.dev/#/patchset/20260422125123.40658-1-ja%40ssi.bg\n> Link: https://sashiko.dev/#/patchset/20260424175858.54752-1-ja%40ssi.bg\n> Fixes: f0be83d54217 (\"ipvs: add est_cpulist and est_nice sysctl vars\")\n> Signed-off-by: Julian Anastasov \n\n\tSashiko found another missing mutex lock [1].\nI'll send new patch version...\n\npw-bot: changes-requested\n\n[1] https://sashiko.dev/#/patchset/20260425103918.7447-1-ja%40ssi.bg\n\nRegards\n\n--\nJulian Anastasov ","headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (4096-bit key;\n unprotected) header.d=ssi.bg header.i=@ssi.bg header.a=rsa-sha256\n header.s=ssi header.b=JgnLwuWE;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; 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