On Sun, Apr 26, 2009 at 01:55:22PM -0400, Trond Myklebust wrote: > On Sun, 2009-04-26 at 17:13 +0200, Nick Piggin wrote: > > This doesn't seem to fix the race, though... on kernels with the > > race still there, it will just open a window where you can have > > a dirty pte but the page not written out. > > > > I don't understand. > > I'm just pointing out that the NFS client already calls > __set_page_dirty_nobuffers() while holding the page lock inside the > nfs_vm_page_mkwrite() call, so having the VM do it too in the call to > set_page_dirty_balance() is actually redundant. IOW: as far as the NFS > code is concerned, we can get rid of the ->set_page_dirty() callback in > that situation. > > I couldn't find any other places in the VM code where we can have a > dirty pte without also having called page_mkwrite() (and hence > __set_page_dirty_nobuffers). As I said, adding a WARN_ON(!PageDirty()) > in ->set_page_dirty() didn't ever trigger any cases where the > set_page_dirty() was actually setting the dirty bit (except in the case > where we race with page writeout in do_wp_page() and __do_fault()). > > That's why I believe disabling ->set_page_dirty() is safe here, and will > in fact suffice to fix the page writeout race. Ah, no I don't think so because it opens another race where the pte is dity but the page is marked clean. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
