Hi, Andrew,
"Huang, Ying" <ying.huang@xxxxxxxxx> writes:
> From: Huang Ying <ying.huang@xxxxxxxxx>
>
> The swap offset reported by /proc/<pid>/pagemap may be not correct for
> PMD migration entry. If addr passed into pagemap_range() isn't
> aligned with PMD start address, the swap offset reported doesn't
> reflect this. And in the loop to report information of each sub-page,
> the swap offset isn't increased accordingly as that for PFN.
>
> BTW: migration swap entries have PFN information, do we need to
> restrict whether to show them?
>
> Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Andrei Vagin <avagin@xxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: "Jerome Glisse" <jglisse@xxxxxxxxxx>
> Cc: Daniel Colascione <dancol@xxxxxxxxxx>
> Cc: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
> ---
> fs/proc/task_mmu.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 65ae54659833..757e748da613 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1310,9 +1310,11 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
> #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
> else if (is_swap_pmd(pmd)) {
> swp_entry_t entry = pmd_to_swp_entry(pmd);
> + unsigned long offset = swp_offset(entry);
>
> + offset += (addr & ~PMD_MASK) >> PAGE_SHIFT;
> frame = swp_type(entry) |
> - (swp_offset(entry) << MAX_SWAPFILES_SHIFT);
> + (offset << MAX_SWAPFILES_SHIFT);
> flags |= PM_SWAP;
> if (pmd_swp_soft_dirty(pmd))
> flags |= PM_SOFT_DIRTY;
> @@ -1332,6 +1334,8 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end,
> break;
> if (pm->show_pfn && (flags & PM_PRESENT))
> frame++;
> + else if (flags | PM_SWAP)
Oops, I just found a typo here, it should be,
+ else if (flags & PM_SWAP)
Sorry about that. Do I need to refresh the patch or you will fix it
inline?
Best Regards,
Huang, Ying
> + frame += (1 << MAX_SWAPFILES_SHIFT);
> }
> spin_unlock(ptl);
> return err;
