On Mon 25-07-16 15:30:59, Ross Zwisler wrote: > On Fri, Jul 22, 2016 at 02:19:40PM +0200, Jan Kara wrote: > > Currently PTE gets updated in wp_pfn_shared() after dax_pfn_mkwrite() > > has released corresponding radix tree entry lock. When we want to > > writeprotect PTE on cache flush, we need PTE modification to happen > > under radix tree entry lock to ensure consisten updates of PTE and radix > > tree (standard faults use page lock to ensure this consistency). So move > > update of PTE bit into dax_pfn_mkwrite(). > > > > Signed-off-by: Jan Kara <jack@xxxxxxx> > > After applying the whole series to a v4.7 baseline I was hitting a deadlock in > my testing, and it bisected to this commit. This deadlock happens in my QEMU > guest with generic/068, ext4 and DAX. It reproduces 100% of the time after > this commit. > > Here is the lockdep info, passed through kasan_symbolize.py: Thanks! I've checked why I didn't see this and apparently I've run last round of testing on the wrong branch. Drat. I've fixed the bug you've spotted (we need to release tree_lock earlier) but xfstests are triggering some more issues now for me so I'm debugging those. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>