path: root/drivers/base/node.c
diff options
authorLee Schermerhorn <>2008-10-18 20:26:52 -0700
committerLinus Torvalds <>2008-10-20 08:52:31 -0700
commit64d6519dda3905dfb94d3f93c07c5f263f41813f (patch)
tree62cae88edcb858c42a5b4b568eb77801299250bb /drivers/base/node.c
parent5344b7e648980cc2ca613ec03a56a8222ff48820 (diff)
swap: cull unevictable pages in fault path
In the fault paths that install new anonymous pages, check whether the page is evictable or not using lru_cache_add_active_or_unevictable(). If the page is evictable, just add it to the active lru list [via the pagevec cache], else add it to the unevictable list. This "proactive" culling in the fault path mimics the handling of mlocked pages in Nick Piggin's series to keep mlocked pages off the lru lists. Notes: 1) This patch is optional--e.g., if one is concerned about the additional test in the fault path. We can defer the moving of nonreclaimable pages until when vmscan [shrink_*_list()] encounters them. Vmscan will only need to handle such pages once, but if there are a lot of them it could impact system performance. 2) The 'vma' argument to page_evictable() is require to notice that we're faulting a page into an mlock()ed vma w/o having to scan the page's rmap in the fault path. Culling mlock()ed anon pages is currently the only reason for this patch. 3) We can't cull swap pages in read_swap_cache_async() because the vma argument doesn't necessarily correspond to the swap cache offset passed in by swapin_readahead(). This could [did!] result in mlocking pages in non-VM_LOCKED vmas if [when] we tried to cull in this path. 4) Move set_pte_at() to after where we add page to lru to keep it hidden from other tasks that might walk the page table. We already do it in this order in do_anonymous() page. And, these are COW'd anon pages. Is this safe? [ undo an overzealous code cleanup] Signed-off-by: Lee Schermerhorn <> Signed-off-by: Rik van Riel <> Signed-off-by: KOSAKI Motohiro <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'drivers/base/node.c')
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