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 jF2kGVwW 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 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 2025-11-07 09:43, Mathieu Desnoyers wrote: > On 2025-11-06 19:32, Shakeel Butt wrote: > > [...] > >>> [   14.858862][   T67] BUG: Bad rss-counter state mm:ffff8881000655c0 >>> type:MM_ANONPAGES val:0 Comm:kworker/u9:0 Pid:67 >>> [   14.894890][   T69] BUG: Bad rss-counter state mm:ffff888100061cc0 >>> type:MM_FILEPAGES val:0 Comm:kworker/u9:0 Pid:69 >>> [   14.896108][   T69] BUG: Bad rss-counter state mm:ffff888100061cc0 >>> type:MM_ANONPAGES val:0 Comm:kworker/u9:0 Pid:69 >> >> Hmm this shows that percpu_counter_tree_precise_sum() is returning 0 but >> percpu_counter_tree_approximate_sum() is off more than >> counter->inaccuracy. I have not dig deeper to find why but this needs to >> be resolved before considering this series for upstream. > > I notice that those BUG show up while loading modules at boot in kworker > context, e.g.: > > [   14.858862][   T67] BUG: Bad rss-counter state mm:ffff8881000655c0 > type:MM_ANONPAGES val:0 Comm:kworker/u9:0 Pid:67 > [   14.894890][   T69] BUG: Bad rss-counter state mm:ffff888100061cc0 > type:MM_FILEPAGES val:0 Comm:kworker/u9:0 Pid:69 > [   14.896108][   T69] BUG: Bad rss-counter state mm:ffff888100061cc0 > type:MM_ANONPAGES val:0 Comm:kworker/u9:0 Pid:69 > [   14.918858][   T71] module: module-autoload: duplicate request for > module crypto-aes > [   14.919479][   T71] module: module-autoload: duplicate request for > module crypto-aes-all > [   14.920801][    T1] krb5: Running aes128-cts-hmac-sha256-128 enc > plain [   14.921844][    T1] krb5: Running aes128-cts-hmac-sha256-128 enc > plain==block > [   14.922852][    T1] krb5: Running aes128-cts-hmac-sha256-128 enc > plain>block > [   14.923843][    T1] krb5: Running aes256-cts-hmac-sha384-192 enc no > plain > [   14.939591][    T1] krb5: Running aes256-cts-hmac-sha384-192 enc > plain [   14.940614][    T1] krb5: Running aes256-cts-hmac-sha384-192 enc > plain==block > [   14.941586][    T1] krb5: Running aes256-cts-hmac-sha384-192 enc > plain>block > [   14.942547][    T1] krb5: Running camellia128-cts-cmac enc no plain > [   15.018568][   T85] BUG: Bad rss-counter state mm:ffff888160f81340 > type:MM_ANONPAGES val:0 Comm:kworker/u9:0 Pid:85b > > I used "module_init" similarly to lib/percpu_counter.c, but I think it > happens too late in the boot sequence: > >   module_init(percpu_counter_startup); > > module_init maps to __initcall within a built-in compile unit, which > maps to device_initcall(), which happens quite late within the sequence > called from do_initcalls(), called from do_basic_setup(). > > And even do_basic_setup is documented as: > >  * Ok, the machine is now initialized. None of the devices >  * have been touched yet, but the CPU subsystem is up and >  * running, and memory and process management works. > > which clearly requires that the mm subsystem is expected to > be ready at that point. > > It probably was not an issue for the non-hierarchical percpu > counters because all it was initializing is handling of CPU hotplug, > but the new hierarchical counters initialize the pre-calculated > inaccuracy value which is used to figure out whether the approximate > sum is sufficient to compare values or if the precise sum is needed. > > I think this is why we are hitting this BUG. > > Now I wonder where I should move this initialization. It requires > "nr_cpu_ids" to be initialized, and pretty much need to be done > before mms are created. I'm starting to suspect that the module init > code can spawn kworkers that have a mm before the init process runs. At least on x86, nr_cpu_ids appears to be set by set_nr_cpu_ids() through early_param("possible_cpus", setup_possible_cpus), which is AFAIU called from parse_early_param(), which happens very early in the boot sequence. It would make sense to call an explicit percpu counter tree init function from start_kernel() between the call to mm_core_init() and the call to maple_tree_init(). This way it would be initialized right after mm, but given that the hierarchical counter tree is a lib that can be used for other purposes than mm accounting, I think it makes sense to call its init explicitly from start_kernel() rather than bury it within mm_core_init(). Thoughts ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com