Messages in this thread | | | Date | Thu, 21 Oct 2004 14:45:31 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] zap_pte_range should not mark non-uptodate pages dirty |
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Dave Kleikamp <shaggy@austin.ibm.com> wrote: > > Doing O_DIRECT writes to an mmapped file caused pages in the page cache to > be marked dirty but not uptodate. This led to a bug in mpage_writepage. >
Methinks this merely reduces the probability of the BUG.
> diff -urp linux-2.6.9/mm/memory.c linux/mm/memory.c > --- linux-2.6.9/mm/memory.c 2004-10-21 10:49:26.598031488 -0500 > +++ linux/mm/memory.c 2004-10-21 16:01:44.902376232 -0500 > @@ -414,7 +414,15 @@ static void zap_pte_range(struct mmu_gat > && linear_page_index(details->nonlinear_vma, > address+offset) != page->index) > set_pte(ptep, pgoff_to_pte(page->index)); > - if (pte_dirty(pte)) > + /* > + * PG_uptodate can be cleared by > + * invalidate_inode_pages2, so we must not try to write > + * not uptodate pages. Otherwise we risk invalidating > + * underlying O_DIRECT writes, and secondly because > + * pdflush would BUG(). Coherency of mmaps against > + * O_DIRECT still cannot be guaranteed though. > + */ > + if (pte_dirty(pte) && PageUptodate(page))
invalidate_inode_pages2 runs ClearPageUptodate() here
> set_page_dirty(page); > if (pte_young(pte) && !PageAnon(page)) > mark_page_accessed(page);
Maybe we should revisit invalidate_inode_pages2(). It used to be an invariant that "pages which are mapped into process address space are always uptodate". We broke that (good) invariant and we're now seeing some fallout. There may be more. - 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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