Messages in this thread Patch in this message | | | From | Izik Eidus <> | Subject | [PATCH 02/10] ksm: first tidy up madvise_vma() | Date | Fri, 17 Jul 2009 20:30:42 +0300 |
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From: Hugh Dickins <hugh.dickins@tiscali.co.uk>
madvise.c has several levels of switch statements, what to do in which? Move MADV_DOFORK code down from madvise_vma() to madvise_behavior(), so madvise_vma() can be a simple router, to madvise_behavior() by default.
vma->vm_flags is an unsigned long so use the same type for new_flags. Add missing comment lines to describe MADV_DONTFORK and MADV_DOFORK.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Chris Wright <chrisw@redhat.com> Signed-off-by: Izik Eidus <ieidus@redhat.com> --- mm/madvise.c | 39 +++++++++++++-------------------------- 1 files changed, 13 insertions(+), 26 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c index 76eb419..66c3126 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -41,7 +41,7 @@ static long madvise_behavior(struct vm_area_struct * vma, struct mm_struct * mm = vma->vm_mm; int error = 0; pgoff_t pgoff; - int new_flags = vma->vm_flags; + unsigned long new_flags = vma->vm_flags; switch (behavior) { case MADV_NORMAL: @@ -57,6 +57,10 @@ static long madvise_behavior(struct vm_area_struct * vma, new_flags |= VM_DONTCOPY; break; case MADV_DOFORK: + if (vma->vm_flags & VM_IO) { + error = -EINVAL; + goto out; + } new_flags &= ~VM_DONTCOPY; break; } @@ -211,37 +215,16 @@ static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, unsigned long start, unsigned long end, int behavior) { - long error; - switch (behavior) { - case MADV_DOFORK: - if (vma->vm_flags & VM_IO) { - error = -EINVAL; - break; - } - case MADV_DONTFORK: - case MADV_NORMAL: - case MADV_SEQUENTIAL: - case MADV_RANDOM: - error = madvise_behavior(vma, prev, start, end, behavior); - break; case MADV_REMOVE: - error = madvise_remove(vma, prev, start, end); - break; - + return madvise_remove(vma, prev, start, end); case MADV_WILLNEED: - error = madvise_willneed(vma, prev, start, end); - break; - + return madvise_willneed(vma, prev, start, end); case MADV_DONTNEED: - error = madvise_dontneed(vma, prev, start, end); - break; - + return madvise_dontneed(vma, prev, start, end); default: - BUG(); - break; + return madvise_behavior(vma, prev, start, end, behavior); } - return error; } static int @@ -262,6 +245,7 @@ madvise_behavior_valid(int behavior) return 0; } } + /* * The madvise(2) system call. * @@ -286,6 +270,9 @@ madvise_behavior_valid(int behavior) * so the kernel can free resources associated with it. * MADV_REMOVE - the application wants to free up the given range of * pages and associated backing store. + * MADV_DONTFORK - omit this area from child's address space when forking: + * typically, to avoid COWing pages pinned by get_user_pages(). + * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking. * * return values: * zero - success -- 1.5.6.5
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