| From: |
| Peter Zijlstra <peterz@infradead.org> |
| To: |
| linux-kernel <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org> |
| Subject: |
| [rfc][patch] mm: madvise(WILLNEED) for anonymous memory |
| Date: |
| Thu, 20 Dec 2007 14:05:38 +0100 |
| Message-ID: |
| <1198155938.6821.3.camel@twins> |
| Cc: |
| hugh <hugh@veritas.com>, Nick Piggin <npiggin@suse.de>,
riel <riel@redhat.com>, Lennart Poettering <mztabzr@0pointer.de> |
Hi,
Lennart asked for madvise(WILLNEED) to work on anonymous pages, he plans
to use this to pre-fault pages. He currently uses: mlock/munlock for
this purpose.
[ compile tested only ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
diff --git a/mm/madvise.c b/mm/madvise.c
index 93ee375..eff60ce 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -100,6 +100,24 @@ out:
return error;
}
+static long madvice_willneed_anon(struct vm_area_struct *vma,
+ struct vm_area_struct **prev,
+ unsigned long start, unsigned long end)
+{
+ int ret, len;
+
+ *prev = vma;
+ if (end > vma->vm_end)
+ end = vma->vm_end;
+
+ len = end - start;
+ ret = get_user_pages(current, current->mm, start, len,
+ 0, 0, NULL, NULL);
+ if (ret < 0)
+ return ret;
+ return ret == len ? 0 : -1;
+}
+
/*
* Schedule all required I/O operations. Do not wait for completion.
*/
@@ -110,7 +128,7 @@ static long madvise_willneed(struct vm_area_struct * vma,
struct file *file = vma->vm_file;
if (!file)
- return -EBADF;
+ return madvice_willneed_anon(vma, prev, start, end);
if (file->f_mapping->a_ops->get_xip_page) {
/* no bad return value, but ignore advice */
--
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