Messages in this thread | | | Date | Tue, 10 Jan 2023 12:58:32 +0100 (CET) | From | Christoph Lameter <> | Subject | Re: [PATCH v13 1/6] mm/vmstat: Add CPU-specific variable to track a vmstat discrepancy |
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On Thu, 5 Jan 2023, Marcelo Tosatti wrote:
> +static inline void vmstat_mark_dirty(void) > +{ > + this_cpu_write(vmstat_dirty, true); > +}
this_cpu_write() is intended for an per cpu atomic context. You are not using it in that way. The processor may have changed before or after and thus vmstat_dirty for another CPU may have been marked dirty.
I guess this would have to be called __vmstat_mark_dirty() and be using __this_cpu_write(*) with a requirement that preemption be disabled before using this function.
> +static inline void vmstat_clear_dirty(void) > +{ > + this_cpu_write(vmstat_dirty, false); > +}
Same
> +static inline bool is_vmstat_dirty(void) > +{ > + return this_cpu_read(vmstat_dirty); > +}
This function would only work correctly if preemption is disabled. Otherwise the processor may change.
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