diff options
| author | Hugh Dickins <hughd@google.com> | 2017-01-07 15:37:31 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-20 10:18:34 +0100 |
| commit | eede34e949df8eb511a690110543deb4eed5af8f (patch) | |
| tree | 76bf74f6ec4f3d4a096a6ba58ecea837bfc0548a /mm | |
| parent | 43b0861aeee29440b70dfcb3fd6478c76933f928 (diff) | |
mm: stop leaking PageTables
commit b0b9b3df27d100a975b4e8818f35382b64a5e35c upstream.
4.10-rc loadtest (even on x86, and even without THPCache) fails with
"fork: Cannot allocate memory" or some such; and /proc/meminfo shows
PageTables growing.
Commit 953c66c2b22a ("mm: THP page cache support for ppc64") that got
merged in rc1 removed the freeing of an unused preallocated pagetable
after do_fault_around() has called map_pages().
This is usually a good optimization, so that the followup doesn't have
to reallocate one; but it's not sufficient to shift the freeing into
alloc_set_pte(), since there are failure cases (most commonly
VM_FAULT_RETRY) which never reach finish_fault().
Check and free it at the outer level in do_fault(), then we don't need
to worry in alloc_set_pte(), and can restore that to how it was (I
cannot find any reason to pte_free() under lock as it was doing).
And fix a separate pagetable leak, or crash, introduced by the same
change, that could only show up on some ppc64: why does do_set_pmd()'s
failure case attempt to withdraw a pagetable when it never deposited
one, at the same time overwriting (so leaking) the vmf->prealloc_pte?
Residue of an earlier implementation, perhaps? Delete it.
Fixes: 953c66c2b22a ("mm: THP page cache support for ppc64")
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/mm/memory.c b/mm/memory.c index 35d8217bb046..47248dc0b9e1 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3329,15 +3329,24 @@ static int do_fault(struct fault_env *fe) { struct vm_area_struct *vma = fe->vma; pgoff_t pgoff = linear_page_index(vma, fe->address); + int ret; /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */ if (!vma->vm_ops->fault) - return VM_FAULT_SIGBUS; - if (!(fe->flags & FAULT_FLAG_WRITE)) - return do_read_fault(fe, pgoff); - if (!(vma->vm_flags & VM_SHARED)) - return do_cow_fault(fe, pgoff); - return do_shared_fault(fe, pgoff); + ret = VM_FAULT_SIGBUS; + else if (!(fe->flags & FAULT_FLAG_WRITE)) + ret = do_read_fault(fe, pgoff); + else if (!(vma->vm_flags & VM_SHARED)) + ret = do_cow_fault(fe, pgoff); + else + ret = do_shared_fault(fe, pgoff); + + /* preallocated pagetable is unused: free it */ + if (fe->prealloc_pte) { + pte_free(vma->vm_mm, fe->prealloc_pte); + fe->prealloc_pte = 0; + } + return ret; } static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, |