Hi,
Thank you for your reviewing.
On Thu, Dec 29, 2011 at 10:39:18PM -0500, KOSAKI Motohiro wrote:
...
> > --- 3.2-rc5.orig/fs/proc/task_mmu.c
> > +++ 3.2-rc5/fs/proc/task_mmu.c
> > @@ -600,6 +600,9 @@ struct pagemapread {
> > u64 *buffer;
> > };
> >
> > +#define PAGEMAP_WALK_SIZE (PMD_SIZE)
> > +#define PAGEMAP_WALK_MASK (PMD_MASK)
> > +
> > #define PM_ENTRY_BYTES sizeof(u64)
> > #define PM_STATUS_BITS 3
> > #define PM_STATUS_OFFSET (64 - PM_STATUS_BITS)
> > @@ -658,6 +661,22 @@ static u64 pte_to_pagemap_entry(pte_t pte)
> > return pme;
> > }
> >
> > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > +static u64 thp_pte_to_pagemap_entry(pte_t pte, int offset)
> > +{
> > + u64 pme = 0;
> > + if (pte_present(pte))
>
> When does pte_present() return 0?
It does when the page pointed to by pte is swapped-out, under page migration,
or HWPOISONed. But currenly it can't happen on thp because thp will be
splitted before these operations are processed.
So this if-sentense is not necessary for now, but I think it's not a bad idea
to put it now to prepare for future implementation.
>
> > + pme = PM_PFRAME(pte_pfn(pte) + offset)
> > + | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
> > + return pme;
> > +}
> > +#else
> > +static inline u64 thp_pte_to_pagemap_entry(pte_t pte, int offset)
> > +{
> > + return 0;
> > +}
> > +#endif
> > +
> > static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> > struct mm_walk *walk)
> > {
> > @@ -665,14 +684,34 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> > struct pagemapread *pm = walk->private;
> > pte_t *pte;
> > int err = 0;
> > -
> > - split_huge_page_pmd(walk->mm, pmd);
> > + u64 pfn = PM_NOT_PRESENT;
> >
> > /* find the first VMA at or above 'addr' */
> > vma = find_vma(walk->mm, addr);
> > - for (; addr != end; addr += PAGE_SIZE) {
> > - u64 pfn = PM_NOT_PRESENT;
> >
> > + spin_lock(&walk->mm->page_table_lock);
> > + if (pmd_trans_huge(*pmd)) {
> > + if (pmd_trans_splitting(*pmd)) {
> > + spin_unlock(&walk->mm->page_table_lock);
> > + wait_split_huge_page(vma->anon_vma, pmd);
> > + } else {
> > + for (; addr != end; addr += PAGE_SIZE) {
> > + int offset = (addr& ~PAGEMAP_WALK_MASK)
> > + >> PAGE_SHIFT;
>
> implicit narrowing conversion. offset should be unsigned long.
OK.
>
>
> > + pfn = thp_pte_to_pagemap_entry(*(pte_t *)pmd,
> > + offset);
>
> This (pte_t*) cast looks introduce new implicit assumption. Please don't
> put x86 assumption here directly.
OK, I think it's better to write a separate patch for this job because
similar assumption is used in smaps_pte_range() and gather_pte_stats().
>
>
> > + err = add_to_pagemap(addr, pfn, pm);
> > + if (err)
> > + break;
> > + }
> > + spin_unlock(&walk->mm->page_table_lock);
> > + return err;
> > + }
> > + } else {
> > + spin_unlock(&walk->mm->page_table_lock);
> > + }
>
> coding standard violation. plz run check_patch.pl.
checkpatch.pl says nothing for here. According to Documentation/CodingStyle,
"no braces for single statement" rule is not applicable for else-blocks with
one statement if corresponding if-blocks have multiple statements.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>