From: Naoya Horiguchi Date: Tue, 11 May 2010 21:06:55 +0000 (-0700) Subject: rmap: remove anon_vma check in page_address_in_vma() X-Git-Tag: v2.6.34~40 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=ab941e0fff3947b6dcc9c578d918d1bba54a6874;hp=4a6018f7f4f1075c1a5403b5ec0ee7262187b86c rmap: remove anon_vma check in page_address_in_vma() Currently page_address_in_vma() compares vma->anon_vma and page_anon_vma(page) for parameter check, but in 2.6.34 a vma can have multiple anon_vmas with anon_vma_chain, so current check does not work. (For anonymous page shared by multiple processes, some verified (page,vma) pairs return -EFAULT wrongly.) We can go to checking all anon_vmas in the "same_vma" chain, but it needs to meet lock requirement. Instead, we can remove anon_vma check safely because page_address_in_vma() assumes that page and vma are already checked to belong to the identical process. Signed-off-by: Naoya Horiguchi Reviewed-by: Rik van Riel Cc: Andi Kleen Cc: Andrea Arcangeli Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/rmap.c b/mm/rmap.c index 07fc94758799..0feeef860a8f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -336,14 +336,13 @@ vma_address(struct page *page, struct vm_area_struct *vma) /* * At what user virtual address is page expected in vma? - * checking that the page matches the vma. + * Caller should check the page is actually part of the vma. */ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) { - if (PageAnon(page)) { - if (vma->anon_vma != page_anon_vma(page)) - return -EFAULT; - } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { + if (PageAnon(page)) + ; + else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping) return -EFAULT;