diff options
| author | Matthew Wilcox <matthew.r.wilcox@intel.com> | 2016-02-02 16:57:57 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-02-03 08:28:43 -0800 |
| commit | 12c9d70bd5056b3ae84746fca973c286f48384cc (patch) | |
| tree | f6b95cb55c397b738b8509c03d895fa8e2bd6f21 /mm/huge_memory.c | |
| parent | c6400ba7e13a41539342f1b6e1f9e78419cb0148 (diff) | |
| download | lwn-12c9d70bd5056b3ae84746fca973c286f48384cc.tar.gz lwn-12c9d70bd5056b3ae84746fca973c286f48384cc.zip | |
mm: fix memory leak in copy_huge_pmd()
We allocate a pgtable but do not attach it to anything if the PMD is in
a DAX VMA, causing it to leak.
We certainly try to not free pgtables associated with the huge zero page
if the zero page is in a DAX VMA, so I think this is the right solution.
This needs to be properly audited.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c1411961167e..36c070167b71 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -858,7 +858,8 @@ static bool set_huge_zero_page(pgtable_t pgtable, struct mm_struct *mm, return false; entry = mk_pmd(zero_page, vma->vm_page_prot); entry = pmd_mkhuge(entry); - pgtable_trans_huge_deposit(mm, pmd, pgtable); + if (pgtable) + pgtable_trans_huge_deposit(mm, pmd, pgtable); set_pmd_at(mm, haddr, pmd, entry); atomic_long_inc(&mm->nr_ptes); return true; @@ -1036,13 +1037,15 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, spinlock_t *dst_ptl, *src_ptl; struct page *src_page; pmd_t pmd; - pgtable_t pgtable; + pgtable_t pgtable = NULL; int ret; - ret = -ENOMEM; - pgtable = pte_alloc_one(dst_mm, addr); - if (unlikely(!pgtable)) - goto out; + if (!vma_is_dax(vma)) { + ret = -ENOMEM; + pgtable = pte_alloc_one(dst_mm, addr); + if (unlikely(!pgtable)) + goto out; + } dst_ptl = pmd_lock(dst_mm, dst_pmd); src_ptl = pmd_lockptr(src_mm, src_pmd); @@ -1073,7 +1076,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, goto out_unlock; } - if (pmd_trans_huge(pmd)) { + if (!vma_is_dax(vma)) { /* thp accounting separate from pmd_devmap accounting */ src_page = pmd_page(pmd); VM_BUG_ON_PAGE(!PageHead(src_page), src_page); |