Messages in this thread Patch in this message | | | Date | Mon, 2 Dec 2013 14:44:34 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 1/9] mm/rmap: recompute pgoff for huge page |
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On Thu, 28 Nov 2013 16:48:38 +0900 Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> We have to recompute pgoff if the given page is huge, since result based > on HPAGE_SIZE is not approapriate for scanning the vma interval tree, as > shown by commit 36e4f20af833 ("hugetlb: do not use vma_hugecache_offset() > for vma_prio_tree_foreach") and commit 369a713e ("rmap: recompute pgoff > for unmapping huge page"). > > ... > > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1714,6 +1714,10 @@ static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, > > if (!mapping) > return ret; > + > + if (PageHuge(page)) > + pgoff = page->index << compound_order(page); > + > mutex_lock(&mapping->i_mmap_mutex); > vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { > unsigned long address = vma_address(page, vma);
a) Can't we just do this?
--- a/mm/rmap.c~mm-rmap-recompute-pgoff-for-huge-page-fix +++ a/mm/rmap.c @@ -1708,16 +1708,13 @@ static int rmap_walk_file(struct page *p struct vm_area_struct *, unsigned long, void *), void *arg) { struct address_space *mapping = page->mapping; - pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); + pgoff_t pgoff = page->index << compound_order(page); struct vm_area_struct *vma; int ret = SWAP_AGAIN; if (!mapping) return ret; - if (PageHuge(page)) - pgoff = page->index << compound_order(page); - mutex_lock(&mapping->i_mmap_mutex); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { unsigned long address = vma_address(page, vma); compound_order() does the right thing for all styles of page, yes?
b) If that PageHuge() test you added the correct thing to use?
/* * PageHuge() only returns true for hugetlbfs pages, but not for normal or * transparent huge pages. See the PageTransHuge() documentation for more * details. */ Obviously we won't be encountering transparent huge pages here, but what's the best future-safe approach?
I hate that PageHuge() oddity with a passion! Maybe it would be better if it was called PageHugetlbfs.
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