Hi, A minor update from v3 here: https://lore.kernel.org/r/20220406180922.1522433-1-catalin.marinas@xxxxxxx In patch 3/3 I dropped the 'len' local variable, so the btrfs patch simply replaces fault_in_writeable() with fault_in_subpage_writeable() and adds a comment. I kept David's ack as there's no functional change since v3. Andrew, since there was no objection last time around, I'd like this series to land in 5.19. As it touches arch, fs and mm, it should probably go in via the mm tree but I'm also happy to merge the series via arm64. Please let me know if you have any preference. The btrfs search_ioctl() function can potentially live-lock on arm64 with MTE enabled due to a fault_in_writeable() + copy_to_user_nofault() unbounded loop. The uaccess can fault in the middle of a page (MTE tag check fault) even if a prior fault_in_writeable() successfully wrote to the beginning of that page. The btrfs loop always restarts the fault-in loop from the beginning of the user buffer, hence the live-lock. The series introduces fault_in_subpage_writeable() together with the arm64 probing counterpart and the btrfs fix. Thanks. Catalin Marinas (3): mm: Add fault_in_subpage_writeable() to probe at sub-page granularity arm64: Add support for user sub-page fault probing btrfs: Avoid live-lock in search_ioctl() on hardware with sub-page faults arch/Kconfig | 7 +++++++ arch/arm64/Kconfig | 1 + arch/arm64/include/asm/mte.h | 1 + arch/arm64/include/asm/uaccess.h | 15 +++++++++++++++ arch/arm64/kernel/mte.c | 30 ++++++++++++++++++++++++++++++ fs/btrfs/ioctl.c | 7 ++++++- include/linux/pagemap.h | 1 + include/linux/uaccess.h | 22 ++++++++++++++++++++++ mm/gup.c | 29 +++++++++++++++++++++++++++++ 9 files changed, 112 insertions(+), 1 deletion(-) base-commit: b2d229d4ddb17db541098b83524d901257e93845
