Rik van Riel wrote:
This should fix the MADV_FREE code for PPC's hashed tlb.
Signed-off-by: Rik van Riel <[EMAIL PROTECTED]>
---
Nick Piggin wrote:
Nick Piggin wrote:
3) because of this, we can treat any such accesses as
happening simultaneously with the MADV_FREE and
as illegal, aka undefined behaviour territory and
we do not need to worry about them
Yes, but I'm wondering if it is legal in all architectures.
It's similar to trying to access memory during an munmap.
You may be able to for a short time, but it'll come back to
haunt you.
The question is whether the architecture specific tlb
flushing code will break or not.
I guess we'll need to call tlb_remove_tlb_entry() inside the
MADV_FREE code to keep powerpc happy.
Thanks for pointing this one out.
Even then we do. Each invocation of zap_pte_range() only touches
one page table page, and it flushes the TLB before releasing the
page table lock.
What kernel are you looking at? -rc7 and rc6-mm1 don't, AFAIKS.
Oh dear. I see it now...
The tlb end things inside zap_pte_range() are actually
noops and the actual tlb flush only happens inside
zap_page_range().
I guess the fact that munmap gets the mmap_sem for
writing should save us, though...
What about an unmap_mapping_range, or another MADV_FREE or
MADV_DONTNEED?
------------------------------------------------------------------------
--- linux-2.6.20.x86_64/mm/memory.c.noppc 2007-04-23 21:50:09.000000000
-0400
+++ linux-2.6.20.x86_64/mm/memory.c 2007-04-23 21:48:59.000000000 -0400
@@ -679,6 +679,7 @@ static unsigned long zap_pte_range(struc
}
ptep_test_and_clear_dirty(vma, addr,
pte);
ptep_test_and_clear_young(vma, addr,
pte);
+ tlb_remove_tlb_entry(tlb, pte, addr);
SetPageLazyFree(page);
if (PageActive(page))
deactivate_tail_page(page);
--
SUSE Labs, Novell Inc.
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