Messages in this thread | | | Date | Thu, 5 Oct 2023 18:06:19 +0100 | Subject | Re: [PATCH v6 02/24] x86/resctrl: kfree() rmid_ptrs from rdtgroup_exit() | From | James Morse <> |
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Hi Babu,
On 04/10/2023 19:00, Moger, Babu wrote: > On 9/14/23 12:21, James Morse wrote: >> rmid_ptrs[] is allocated from dom_data_init() but never free()d. >> >> While the exit text ends up in the linker script's DISCARD section, >> the direction of travel is for resctrl to be/have loadable modules. >> >> Add resctrl_exit_mon_l3_config() to cleanup any memory allocated >> by rdt_get_mon_l3_config(). >> >> There is no reason to backport this to a stable kernel.
>> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h >> index 85ceaf9a31ac..57cf1e6a57bd 100644 >> --- a/arch/x86/kernel/cpu/resctrl/internal.h >> +++ b/arch/x86/kernel/cpu/resctrl/internal.h >> @@ -537,6 +537,7 @@ void closid_free(int closid); >> int alloc_rmid(void); >> void free_rmid(u32 rmid); >> int rdt_get_mon_l3_config(struct rdt_resource *r); >> +void resctrl_exit_mon_l3_config(struct rdt_resource *r); >> bool __init rdt_cpu_has(int flag); >> void mon_event_count(void *info); >> int rdtgroup_mondata_show(struct seq_file *m, void *arg); >> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c >> index ded1fc7cb7cb..cfb3f632a4b2 100644 >> --- a/arch/x86/kernel/cpu/resctrl/monitor.c >> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c >> @@ -741,6 +741,16 @@ static int dom_data_init(struct rdt_resource *r) >> return 0; >> } >> >> +void resctrl_exit_mon_l3_config(struct rdt_resource *r) >> +{ >> + mutex_lock(&rdtgroup_mutex); >> + >> + kfree(rmid_ptrs); >> + rmid_ptrs = NULL; >> + >> + mutex_unlock(&rdtgroup_mutex); >> +}
> What is the need for passing "rdt_resource *r" here?
My vain belief that monitors should be supported on something other than L3, but I agree that isn't what resctrl does today. I'll remove it.
> Is mutex_lock required?
Reads and writes to rmid_ptrs[] are protected by that lock. This ensures no-one reads the value while its being free()d, and after this function releases the lock, anyone trying sees NULL.
(This is all moot as its only caller is marked __exit, so gets discarded by the linker)
Thanks,
James
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