| From foo@baz Sun Jun 17 12:07:33 CEST 2018 |
| From: Huang Ying <ying.huang@intel.com> |
| Date: Fri, 20 Apr 2018 14:55:38 -0700 |
| Subject: mm, pagemap: fix swap offset value for PMD migration entry |
| |
| From: Huang Ying <ying.huang@intel.com> |
| |
| [ Upstream commit 88c28f2469151b031f8cea9b28ed5be1b74a4172 ] |
| |
| The swap offset reported by /proc/<pid>/pagemap may be not correct for |
| PMD migration entries. If addr passed into pagemap_pmd_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. |
| |
| This may happen after opening /proc/<pid>/pagemap and seeking to a page |
| whose address doesn't align with a PMD start address. I have verified |
| this with a simple test program. |
| |
| BTW: migration swap entries have PFN information, do we need to restrict |
| whether to show them? |
| |
| [akpm@linux-foundation.org: fix typo, per Huang, Ying] |
| Link: http://lkml.kernel.org/r/20180408033737.10897-1-ying.huang@intel.com |
| Signed-off-by: "Huang, Ying" <ying.huang@intel.com> |
| Cc: Michal Hocko <mhocko@suse.com> |
| Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> |
| Cc: Andrei Vagin <avagin@openvz.org> |
| Cc: Dan Williams <dan.j.williams@intel.com> |
| Cc: "Jerome Glisse" <jglisse@redhat.com> |
| Cc: Daniel Colascione <dancol@google.com> |
| Cc: Zi Yan <zi.yan@cs.rutgers.edu> |
| Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> |
| Cc: Alexey Dobriyan <adobriyan@gmail.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| fs/proc/task_mmu.c | 6 +++++- |
| 1 file changed, 5 insertions(+), 1 deletion(-) |
| |
| --- a/fs/proc/task_mmu.c |
| +++ b/fs/proc/task_mmu.c |
| @@ -1329,9 +1329,11 @@ static int pagemap_pmd_range(pmd_t *pmdp |
| #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; |
| @@ -1351,6 +1353,8 @@ static int pagemap_pmd_range(pmd_t *pmdp |
| break; |
| if (pm->show_pfn && (flags & PM_PRESENT)) |
| frame++; |
| + else if (flags & PM_SWAP) |
| + frame += (1 << MAX_SWAPFILES_SHIFT); |
| } |
| spin_unlock(ptl); |
| return err; |