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    SubjectRe: [PATCH V3 6/8] mm: and drivers core: Convert hugetlb_report_node_meminfo to sysfs_emit
    On Wed, Sep 16, 2020 at 01:40:43PM -0700, Joe Perches wrote:
    > Convert the unbound sprintf in hugetlb_report_node_meminfo to use
    > sysfs_emit_at so that no possible overrun of a PAGE_SIZE buf can occur.
    >
    > Signed-off-by: Joe Perches <joe@perches.com>
    > ---
    > drivers/base/node.c | 2 +-
    > include/linux/hugetlb.h | 4 ++--
    > mm/hugetlb.c | 18 ++++++++++--------
    > 3 files changed, 13 insertions(+), 11 deletions(-)
    >
    > diff --git a/drivers/base/node.c b/drivers/base/node.c
    > index b33526a9fcfc..dafe03e82e7c 100644
    > --- a/drivers/base/node.c
    > +++ b/drivers/base/node.c
    > @@ -473,7 +473,7 @@ static ssize_t node_read_meminfo(struct device *dev,
    > HPAGE_PMD_NR)
    > #endif
    > );
    > - len += hugetlb_report_node_meminfo(nid, buf + len);
    > + len += hugetlb_report_node_meminfo(buf, len, nid);
    > return len;
    > }
    >
    > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
    > index d5cc5f802dd4..ebca2ef02212 100644
    > --- a/include/linux/hugetlb.h
    > +++ b/include/linux/hugetlb.h
    > @@ -129,7 +129,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
    > unsigned long start, unsigned long end,
    > struct page *ref_page);
    > void hugetlb_report_meminfo(struct seq_file *);
    > -int hugetlb_report_node_meminfo(int, char *);
    > +int hugetlb_report_node_meminfo(char *buf, int len, int nid);
    > void hugetlb_show_meminfo(void);
    > unsigned long hugetlb_total_pages(void);
    > vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
    > @@ -245,7 +245,7 @@ static inline void hugetlb_report_meminfo(struct seq_file *m)
    > {
    > }
    >
    > -static inline int hugetlb_report_node_meminfo(int nid, char *buf)
    > +static inline int hugetlb_report_node_meminfo(char *buf, int len, int nid)
    > {
    > return 0;
    > }
    > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
    > index 61469fd3ad92..fe76f8fd5a73 100644
    > --- a/mm/hugetlb.c
    > +++ b/mm/hugetlb.c
    > @@ -3571,18 +3571,20 @@ void hugetlb_report_meminfo(struct seq_file *m)
    > seq_printf(m, "Hugetlb: %8lu kB\n", total / 1024);
    > }
    >
    > -int hugetlb_report_node_meminfo(int nid, char *buf)
    > +int hugetlb_report_node_meminfo(char *buf, int len, int nid)
    > {
    > struct hstate *h = &default_hstate;
    > +
    > if (!hugepages_supported())
    > return 0;
    > - return sprintf(buf,
    > - "Node %d HugePages_Total: %5u\n"
    > - "Node %d HugePages_Free: %5u\n"
    > - "Node %d HugePages_Surp: %5u\n",
    > - nid, h->nr_huge_pages_node[nid],
    > - nid, h->free_huge_pages_node[nid],
    > - nid, h->surplus_huge_pages_node[nid]);
    > +
    > + return sysfs_emit_at(buf, len,
    > + "Node %d HugePages_Total: %5u\n"
    > + "Node %d HugePages_Free: %5u\n"
    > + "Node %d HugePages_Surp: %5u\n",
    > + nid, h->nr_huge_pages_node[nid],
    > + nid, h->free_huge_pages_node[nid],
    > + nid, h->surplus_huge_pages_node[nid]);
    > }

    That is NOT one-value-per-file, which is required for sysfs files. This
    should be 3 different sysfs files.

    Ugh.

    But that's separate from this series, thanks for redoing this. I'll
    take a look at it on Monday...

    thanks,

    greg k-h

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