Messages in this thread Patch in this message | | | Date | Tue, 19 Dec 2006 16:23:08 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: 2.6.19 file content corruption on ext3 |
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On Wed, 20 Dec 2006, Peter Zijlstra wrote: > On Mon, 2006-12-18 at 12:14 -0800, Linus Torvalds wrote: > > OR: > > > > - page_mkclean_one() is simply buggy. > > GOLD!
Ok. I was looking at that, and I wondered..
However, if that works, then I _think_ the correct sequence is the following..
The rule should be: - we flush the tlb _after_ we have cleared it, but _before_ we insert the new entry.
But I dunno. These things are damn subtle. Does this patch fix it for you?
I actually suspect we should do this as an arch-specific macro, and totally replace the current "ptep_clear_flush_dirty()" with one that does "ptep_clear_flush_dirty_and_set_wp()".
Because what I'd _really_ prefer to do on x86 (and probably on most other sane architectures) is to do
- atomically replace the pte with the EXACT SAME ONE, but one that has the writable bit clear.
bit_clear(_PAGE_BIT_RW, &(ptep)->pte_low);
- flush the TLB, making sure that all CPU's will no longer write to it:
flush_tlb_page(vma, address);
- finally, just fetch-and-clear the dirty bit (and since it's no longer writable, nobody should be settign it any more)
ret = bit_clear(__PAGE_BIT_DIRTY, &(ptep)->pte_low);
and now we should be all done.
But the "ptep_get_and_clear() + flush_tlb_page()" sequence should hopefully also work.
Pls test.
Linus
---- diff --git a/mm/rmap.c b/mm/rmap.c index d8a842a..eec8706 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -448,9 +448,10 @@ static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) goto unlock; entry = ptep_get_and_clear(mm, address, pte); + flush_tlb_page(vma, address); entry = pte_mkclean(entry); entry = pte_wrprotect(entry); - ptep_establish(vma, address, pte, entry); + set_pte_at(mm, address, pte, entry); lazy_mmu_prot_update(entry); ret = 1; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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