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authorJohn Hubbard <jhubbard@nvidia.com>2018-11-30 14:08:53 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-11-30 14:56:13 -0800
commit08be37b798921af207e78082fe261a6ca8be5024 (patch)
tree9b493008c4698a62b4a7c43d9ce4383ea43fdd6e
parent12457e6391e000820bb0b2b775125a569c3e80ed (diff)
mm/gup: finish consolidating error handling
Commit df06b37ffe5a ("mm/gup: cache dev_pagemap while pinning pages") attempted to operate on each page that get_user_pages had retrieved. In order to do that, it created a common exit point from the routine. However, one case was missed, which this patch fixes up. Also, there was still an unnecessary shadow declaration (with a different type) of the "ret" variable, which this patch removes. Keith's description of the situation is: This also fixes a potentially leaked dev_pagemap reference count if a failure occurs when an iteration crosses a vma boundary. I don't think it's normal to have different vma's on a users mapped zone device memory, but good to fix anyway. I actually thought that this code: /* first iteration or cross vma bound */ if (!vma || start >= vma->vm_end) { vma = find_extend_vma(mm, start); if (!vma && in_gate_area(mm, start)) { ret = get_gate_page(mm, start & PAGE_MASK, gup_flags, &vma, pages ? &pages[i] : NULL); if (ret) goto out; dealt with the "you're trying to pin the gate page, as part of this call", rather than the generic case of crossing a vma boundary. (I think there's a fine point that I must be overlooking.) But it's still a valid case, either way. Link: http://lkml.kernel.org/r/20181121081402.29641-2-jhubbard@nvidia.com Fixes: df06b37ffe5a4 ("mm/gup: cache dev_pagemap while pinning pages") Signed-off-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/gup.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/mm/gup.c b/mm/gup.c
index aa43620a3270..8cb68a50dbdf 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -702,12 +702,11 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
if (!vma || start >= vma->vm_end) {
vma = find_extend_vma(mm, start);
if (!vma && in_gate_area(mm, start)) {
- int ret;
ret = get_gate_page(mm, start & PAGE_MASK,
gup_flags, &vma,
pages ? &pages[i] : NULL);
if (ret)
- return i ? : ret;
+ goto out;
ctx.page_mask = 0;
goto next_page;
}