From ca120cf688874f4423e579e7cc5ddf7244aeca45 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sat, 3 Sep 2016 10:38:03 -0700 Subject: mm: fix show_smap() for zone_device-pmd ranges Attempting to dump /proc//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:[] [] follow_trans_huge_pmd+0x2cb/0x340 [..] Call Trace: [] smaps_pte_range+0xa0/0x4b0 [] ? vsnprintf+0x255/0x4c0 [] __walk_page_range+0x1fe/0x4d0 [] walk_page_vma+0x62/0x80 [] show_smap+0xa6/0x2b0 kernel BUG at fs/proc/task_mmu.c:585! RIP: 0010:[] [] smaps_pte_range+0x499/0x4b0 Call Trace: [] ? vsnprintf+0x255/0x4c0 [] __walk_page_range+0x1fe/0x4d0 [] walk_page_vma+0x62/0x80 [] 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 Cc: Kirill A. Shutemov Acked-by: Andrew Morton Signed-off-by: Dan Williams --- fs/proc/task_mmu.c | 2 ++ mm/huge_memory.c | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 187d84ef9de9..f6fa99eca515 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -581,6 +581,8 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, mss->anonymous_thp += HPAGE_PMD_SIZE; else if (PageSwapBacked(page)) mss->shmem_thp += HPAGE_PMD_SIZE; + else if (is_zone_device_page(page)) + /* pass */; else VM_BUG_ON_PAGE(1, page); smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd)); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 2db2112aa31e..a6abd76baa72 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1078,7 +1078,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, 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 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, } 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); -- cgit