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SubjectRe: [PATCH] Fix display of Maximum Memory
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Le 14/01/2020 à 22:07, Michael Bringmann a écrit :
> Correct overflow problem in calculation+display of Maximum Memory
> value to syscfg where 32bits is insufficient.
>
> Signed-off-by: Michael Bringmann <mwb@linux.ibm.com>
> ---
> arch/powerpc/platforms/pseries/lparcfg.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
> index 4ee2594..183aeb7 100644
> --- a/arch/powerpc/platforms/pseries/lparcfg.c
> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
> @@ -435,12 +435,12 @@ static void parse_em_data(struct seq_file *m)
>
> static void maxmem_data(struct seq_file *m)
> {
> - unsigned long maxmem = 0;
> + unsigned long long maxmem = 0;

What about using u64 instead, for readability ?

>
> - maxmem += drmem_info->n_lmbs * drmem_info->lmb_size;
> - maxmem += hugetlb_total_pages() * PAGE_SIZE;
> + maxmem += (unsigned long long)drmem_info->n_lmbs * (unsigned long long)drmem_info->lmb_size;

This line is likely too long. You only need to cast one of the two
operants to force a 64 bits multiply. And using u64 would shorten the line.

Can both multiplications overflow ?

Christophe

> + maxmem += (unsigned long long)hugetlb_total_pages() * (unsigned long long)PAGE_SIZE;
>
> - seq_printf(m, "MaxMem=%ld\n", maxmem);
> + seq_printf(m, "MaxMem=%llu\n", maxmem);
> }
>
> static int pseries_lparcfg_data(struct seq_file *m, void *v)
>

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