Messages in this thread | | | Date | Sat, 27 Jul 2013 23:29:36 +0400 | From | Pavel Emelyanov <> | Subject | Re: [PATCH] mm: Save soft-dirty bits on file pages |
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On 07/27/2013 12:55 AM, Andy Lutomirski wrote: > On Fri, Jul 26, 2013 at 1:18 PM, Cyrill Gorcunov <gorcunov@gmail.com> wrote: >> Andy reported that if file page get reclaimed we loose soft-dirty bit >> if it was there, so save _PAGE_BIT_SOFT_DIRTY bit when page address >> get encoded into pte entry. Thus when #pf happens on such non-present >> pte we can restore it back. >> > > Unless I'm misunderstanding this, it's saving the bit in the > non-present PTE. This sounds wrong -- what happens if the entire pmd > (or whatever the next level is called) gets zapped? (Also, what > happens if you unmap a file and map a different file there?)
The whole pte gets zapped on vma unmap, and in this case forgetting the soft-dirty bit completely is OK.
> --Andy > . >
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