mm: fix show_smap() for zone_device-pmd ranges
Attempting to dump /proc/<pid>/smaps for a process with pmd dax mappings
currently results in the following VM_BUG_ONs:
kernel BUG at mm/huge_memory.c:1105!
task: ffff88045f16b140 task.stack: ffff88045be14000
RIP: 0010:[<ffffffff81268f9b>] [<ffffffff81268f9b>] follow_trans_huge_pmd+0x2cb/0x340
[..]
Call Trace:
[<ffffffff81306030>] smaps_pte_range+0xa0/0x4b0
[<ffffffff814c2755>] ? vsnprintf+0x255/0x4c0
[<ffffffff8123c46e>] __walk_page_range+0x1fe/0x4d0
[<ffffffff8123c8a2>] walk_page_vma+0x62/0x80
[<ffffffff81307656>] show_smap+0xa6/0x2b0
kernel BUG at fs/proc/task_mmu.c:585!
RIP: 0010:[<ffffffff81306469>] [<ffffffff81306469>] smaps_pte_range+0x499/0x4b0
Call Trace:
[<ffffffff814c2795>] ? vsnprintf+0x255/0x4c0
[<ffffffff8123c46e>] __walk_page_range+0x1fe/0x4d0
[<ffffffff8123c8a2>] walk_page_vma+0x62/0x80
[<ffffffff81307696>] show_smap+0xa6/0x2b0
These locations are sanity checking page flags that must be set for an
anonymous transparent huge page, but are not set for the zone_device
pages associated with dax mappings.
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2db2112..a6abd76 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1078,7 +1078,7 @@
goto out;
page = pmd_page(*pmd);
- VM_BUG_ON_PAGE(!PageHead(page), page);
+ VM_BUG_ON_PAGE(!PageHead(page) && !is_zone_device_page(page), page);
if (flags & FOLL_TOUCH)
touch_pmd(vma, addr, pmd);
if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
@@ -1116,7 +1116,7 @@
}
skip_mlock:
page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
- VM_BUG_ON_PAGE(!PageCompound(page), page);
+ VM_BUG_ON_PAGE(!PageCompound(page) && !is_zone_device_page(page), page);
if (flags & FOLL_GET)
get_page(page);