diff options
| author | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> | 2017-05-19 09:15:49 +0200 |
|---|---|---|
| committer | Michal Hocko <mhocko@suse.com> | 2017-05-19 09:15:49 +0200 |
| commit | 9d1be922d11819f13d3017972a7327b8c049f8a7 (patch) | |
| tree | e17347d4cb191f175c296209439996f09c354dde | |
| parent | 662792cbfa34006bfb31d5772c8b76c8b26114bd (diff) | |
mm: drop NULL return check of pte_offset_map_lock()
pte_offset_map_lock() finds and takes ptl, and returns pte. But some
callers return without unlocking the ptl when pte == NULL, which seems
weird.
Git history said that !pte check in change_pte_range() was introduced in
commit 1ad9f620c3a2 ("mm: numa: recheck for transhuge pages under lock
during protection changes") and still remains after commit 175ad4f1e7a2
("mm: mprotect: use pmd_trans_unstable instead of taking the pmd_lock")
which partially reverts 1ad9f620c3a2. So I think that it's just dead
code.
Many other caller of pte_offset_map_lock() never check NULL return, so
let's do likewise.
Link: http://lkml.kernel.org/r/1495089737-1292-1-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/memory.c | 2 | ||||
| -rw-r--r-- | mm/mprotect.c | 2 |
2 files changed, 0 insertions, 4 deletions
diff --git a/mm/memory.c b/mm/memory.c index 235ba51b2fbf..d0fa5a215da9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4032,8 +4032,6 @@ static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address, goto out; ptep = pte_offset_map_lock(mm, pmd, address, ptlp); - if (!ptep) - goto out; if (!pte_present(*ptep)) goto unlock; *ptepp = ptep; diff --git a/mm/mprotect.c b/mm/mprotect.c index 8edd0d576254..1a8c9ca83e48 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -58,8 +58,6 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, * reading. */ pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); - if (!pte) - return 0; /* Get target node for single threaded private VMAs */ if (prot_numa && !(vma->vm_flags & VM_SHARED) && |