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| author | Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> | 2017-07-06 15:39:26 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-06 16:24:33 -0700 |
| commit | 8bc3c3fe4f3483374fed4254e47a14ec8c555909 (patch) | |
| tree | ca1f3b9e9ccba747519a47176ea2e7b5dbd33d55 /mm/mprotect.c | |
| parent | d73d3c9f698c5e474e58acbaba87a1f134772747 (diff) | |
| download | lwn-8bc3c3fe4f3483374fed4254e47a14ec8c555909.tar.gz lwn-8bc3c3fe4f3483374fed4254e47a14ec8c555909.zip | |
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>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mprotect.c')
| -rw-r--r-- | mm/mprotect.c | 2 |
1 files changed, 0 insertions, 2 deletions
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) && |