Hello, this and other enhancements have already implemented by Peter (CC'ed) and in the right way, by altering the retry logic in the page fault code. This is a requirement for other kind of usages too, notably the UFFD_WRITEPROTECT ioctl after which multiple consecutive faults can happen and must be handled. IIRC Kirill asked at last LSF-MM uffd-wp talk if there's any particular reason the fault couldn't be retried currently. I had no sure answer other than there's apparently no strong reason why VM_FAULT_RETRY is only allowed 1 time currently, so there should be no issue in lifting that artificial restriction. I'm running with this patchset applied in my systems since Nov with no regression at all. I got sidetracked by various other issues, so unfortunately I didn' post a proper reviewed-by on the last submit yet (pending), but I did at least test it and it was rock solid so far. https://lore.kernel.org/lkml/20190926093904.5090-1-peterx@xxxxxxxxxx/ Can you test and verify it too if it solves your use case? Also note the complete uffd-WP support submit also from Peter: https://lore.kernel.org/lkml/20190620022008.19172-1-peterx@xxxxxxxxxx/ https://github.com/xzpeter/linux/tree/uffd-wp-merged Thanks, Andrea
