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authorNick Piggin <npiggin@suse.de>2009-01-06 14:38:55 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-06 15:58:58 -0800
commitbf3f3bc5e734706730c12a323f9b2068052aa1f0 (patch)
treed93fb6beb0916cc10aeb5674578bfa3ac40371c9 /mm/filemap.c
parent3340289ddf29ca75c3acfb3a6b72f234b2f74d5c (diff)
downloadconfigs-bf3f3bc5e734706730c12a323f9b2068052aa1f0.tar.gz
mm: don't mark_page_accessed in fault path
Doing a mark_page_accessed at fault-time, then doing SetPageReferenced at unmap-time if the pte is young has a number of problems. mark_page_accessed is supposed to be roughly the equivalent of a young pte for unmapped references. Unfortunately it doesn't come with any context: after being called, reclaim doesn't know who or why the page was touched. So calling mark_page_accessed not only adds extra lru or PG_referenced manipulations for pages that are already going to have pte_young ptes anyway, but it also adds these references which are difficult to work with from the context of vma specific references (eg. MADV_SEQUENTIAL pte_young may not wish to contribute to the page being referenced). Then, simply doing SetPageReferenced when zapping a pte and finding it is young, is not a really good solution either. SetPageReferenced does not correctly promote the page to the active list for example. So after removing mark_page_accessed from the fault path, several mmap()+touch+munmap() would have a very different result from several read(2) calls for example, which is not really desirable. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Johannes Weiner <hannes@saeurebad.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/filemap.c')
-rw-r--r--mm/filemap.c1
1 files changed, 0 insertions, 1 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index f5769b4dc07..f9d88183f69 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1530,7 +1530,6 @@ retry_find:
/*
* Found the page and have a reference on it.
*/
- mark_page_accessed(page);
ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
vmf->page = page;
return ret | VM_FAULT_LOCKED;