Messages in this thread | | | Subject | Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmas of a mergeable VMA | From | Peter Zijlstra <> | Date | Mon, 12 Apr 2010 17:33:25 +0200 |
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On Tue, 2010-04-13 at 00:17 +0900, Minchan Kim wrote: > > Concurrent reclaim/gup/whatever could still have a count out on the page > > delaying the actual free beyond the tlb gather RCU section. > > anon_vma lock is just valid in case of page_mapped. > if reclaim/gup/whatever want to use anon_vma, it should check with page_mapped. > And last put_page doesn't touch anon_vma for freeing the page so I > think it's not a problem. Do I miss something?
Hmm, I think you're right. The race I was thinking of makes the page_lock_anon_vma() RCU section overlap with that of the mmu_gather, which ensures the thing is long enough, or hits the !_mapcount case.
I'm not sure there are other page->mapping users that are interesting.
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