Messages in this thread Patch in this message | | | Subject | [PATCH 02/37] mm, frame_vector: do not use get_user_pages_locked() | From | Dave Hansen <> | Date | Mon, 16 Nov 2015 19:35:14 -0800 |
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From: Dave Hansen <dave.hansen@linux.intel.com>
get_user_pages_locked() appears to be for use when a caller needs to know that its lock on mmap_sem was invalidated by the gup call.
But, get_vaddr_frames() is not one of those users. It unconditionally locks the mmap_sem and unconditionally unlocks it after the gup call. It takes no special action and does not need to know whether its lock was invalidated or not.
Replace get_user_pages_locked() with a vanilla get_user_pages() and save a few lines of code.
Note that this was the *ONLY* use of get_user_pages_locked() in the entire kernel tree.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> ---
b/mm/frame_vector.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
diff -puN mm/frame_vector.c~remove-get_user_pages_locked-user mm/frame_vector.c --- a/mm/frame_vector.c~remove-get_user_pages_locked-user 2015-11-16 12:35:35.282169293 -0800 +++ b/mm/frame_vector.c 2015-11-16 12:35:35.285169429 -0800 @@ -40,7 +40,6 @@ int get_vaddr_frames(unsigned long start struct vm_area_struct *vma; int ret = 0; int err; - int locked; if (nr_frames == 0) return 0; @@ -49,7 +48,6 @@ int get_vaddr_frames(unsigned long start nr_frames = vec->nr_allocated; down_read(&mm->mmap_sem); - locked = 1; vma = find_vma_intersection(mm, start, start + 1); if (!vma) { ret = -EFAULT; @@ -58,8 +56,8 @@ int get_vaddr_frames(unsigned long start if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) { vec->got_ref = true; vec->is_pfns = false; - ret = get_user_pages_locked(current, mm, start, nr_frames, - write, force, (struct page **)(vec->ptrs), &locked); + ret = get_user_pages(current, mm, start, nr_frames, + write, force, (struct page **)(vec->ptrs), NULL); goto out; } @@ -87,8 +85,7 @@ int get_vaddr_frames(unsigned long start vma = find_vma_intersection(mm, start, start + 1); } while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP)); out: - if (locked) - up_read(&mm->mmap_sem); + up_read(&mm->mmap_sem); if (!ret) ret = -EFAULT; if (ret > 0) _
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