On Sat, Feb 16, 2019 at 9:29 AM Matthew Wilcox <wi...@infradead.org> wrote: > > On Sat, Feb 16, 2019 at 07:35:11AM -0800, Matthew Wilcox wrote: > > Another way to fix this would be to mask the address in dax_entry_mkclean(), > > but I think this is cleaner. > > That's clearly rubbish, dax_entry_mkclean() can't possibly mask the > address. It might be mis-aligned in another process. But ... if it's > misaligned in another process, dax_entry_mkclean() will only clean the first > PTE associated with the PMD; it won't clean the whole thing. I think we need > something like this: > > (I'll have to split it apart to give us something to backport)
Looks good to me, care to send a formal patch? Tested-by: Dan Williams <dan.j.willi...@intel.com> > > diff --git a/fs/dax.c b/fs/dax.c > index 6959837cc465..09680aa0481f 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -768,7 +768,7 @@ unsigned long pgoff_address(pgoff_t pgoff, struct > vm_area_struct *vma) > > /* Walk all mappings of a given index of a file and writeprotect them */ > static void dax_entry_mkclean(struct address_space *mapping, pgoff_t index, > - unsigned long pfn) > + pgoff_t end, unsigned long pfn) > { > struct vm_area_struct *vma; > pte_t pte, *ptep = NULL; > @@ -776,7 +776,7 @@ static void dax_entry_mkclean(struct address_space > *mapping, pgoff_t index, > spinlock_t *ptl; > > i_mmap_lock_read(mapping); > - vma_interval_tree_foreach(vma, &mapping->i_mmap, index, index) { > + vma_interval_tree_foreach(vma, &mapping->i_mmap, index, end) { > struct mmu_notifier_range range; > unsigned long address; > > @@ -843,9 +843,9 @@ static void dax_entry_mkclean(struct address_space > *mapping, pgoff_t index, > static int dax_writeback_one(struct xa_state *xas, struct dax_device > *dax_dev, > struct address_space *mapping, void *entry) > { > - unsigned long pfn; > + unsigned long pfn, index; > long ret = 0; > - size_t size; > + unsigned long count; > > /* > * A page got tagged dirty in DAX mapping? Something is seriously > @@ -894,17 +894,18 @@ static int dax_writeback_one(struct xa_state *xas, > struct dax_device *dax_dev, > xas_unlock_irq(xas); > > /* > - * Even if dax_writeback_mapping_range() was given a wbc->range_start > - * in the middle of a PMD, the 'index' we are given will be aligned to > - * the start index of the PMD, as will the pfn we pull from 'entry'. > + * If dax_writeback_mapping_range() was given a wbc->range_start > + * in the middle of a PMD, the 'index' we are given needs to be > + * aligned to the start index of the PMD. > * This allows us to flush for PMD_SIZE and not have to worry about > * partial PMD writebacks. > */ > pfn = dax_to_pfn(entry); > - size = PAGE_SIZE << dax_entry_order(entry); > + count = 1UL << dax_entry_order(entry); > + index = xas->xa_index &~ (count - 1); > > - dax_entry_mkclean(mapping, xas->xa_index, pfn); > - dax_flush(dax_dev, page_address(pfn_to_page(pfn)), size); > + dax_entry_mkclean(mapping, index, index + count - 1, pfn); > + dax_flush(dax_dev, page_address(pfn_to_page(pfn)), count * PAGE_SIZE); > /* > * After we have flushed the cache, we can clear the dirty tag. There > * cannot be new dirty data in the pfn after the flush has completed > as > @@ -917,8 +918,7 @@ static int dax_writeback_one(struct xa_state *xas, struct > dax_device *dax_dev, > xas_clear_mark(xas, PAGECACHE_TAG_DIRTY); > dax_wake_entry(xas, entry, false); > > - trace_dax_writeback_one(mapping->host, xas->xa_index, > - size >> PAGE_SHIFT); > + trace_dax_writeback_one(mapping->host, xas->xa_index, count); > return ret; > > put_unlocked: > _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm