On Sat, Oct 17, 2015 at 03:22:19PM -0400, Sasha Levin wrote: > On 09/30/2015 05:30 PM, Sasha Levin wrote: > > On 09/17/2015 10:24 PM, Sasha Levin wrote: > >> On 08/19/2015 01:46 AM, Al Viro wrote: > >>>> or mapping->a_ops->direct_IO() returned more > >>>>> than 'count'. > >>> Was there DAX involved? ->direct_IO() in there is blkdev_direct_IO(), > >>> which takes rather different paths in those cases... > >>> > >> > >> So I've traced this all the way back to dax_io(). I can trigger this with: > >> > >> diff --git a/fs/dax.c b/fs/dax.c > >> index 93bf2f9..2cdb8a5 100644 > >> --- a/fs/dax.c > >> +++ b/fs/dax.c > >> @@ -178,6 +178,7 @@ static ssize_t dax_io(struct inode *inode, struct > >> iov_iter *iter, > >> if (need_wmb) > >> wmb_pmem(); > >> > >> + WARN_ON((pos == start) && (pos - start > iov_iter_count(iter))); > >> return (pos == start) ? retval : pos - start; > >> } > >> > >> So it seems that iter gets moved twice here: once in dax_io(), and once > >> again > >> back at generic_file_read_iter(). > >> > >> I don't see how it ever worked. Am I missing something? > > > > Ping? > > Ping?
I'll try and find time to look at this issue this week. Sasha, do you have a more targeted reproducer, or is still just the trinity fuzzer? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
