The patch titled Subject: btrfs: avoid live-lock in search_ioctl() on hardware with sub-page faults has been removed from the -mm tree. Its filename was btrfs-avoid-live-lock-in-search_ioctl-on-hardware-with-sub-page-faults.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------ From: Catalin Marinas catalin.marinas@arm.com Subject: btrfs: avoid live-lock in search_ioctl() on hardware with sub-page faults

Commit a48b73eca4ce ("btrfs: fix potential deadlock in the search ioctl") addressed a lockdep warning by pre-faulting the user pages and attempting the copy_to_user_nofault() in an infinite loop. On architectures like arm64 with MTE, an access may fault within a page at a location different from what fault_in_writeable() probed. Since the sk_offset is rewound to the previous struct btrfs_ioctl_search_header boundary, there is no guaranteed forward progress and search_ioctl() may live-lock.

Use fault_in_exact_writeable() instead which probes the entire user buffer for faults at sub-page granularity.

Link: https://lkml.kernel.org/r/20211124192024.2408218-4-catalin.marinas@arm.com Fixes: a48b73eca4ce ("btrfs: fix potential deadlock in the search ioctl") Signed-off-by: Catalin Marinas catalin.marinas@arm.com Reported-by: Al Viro viro@zeniv.linux.org.uk Acked-by: David Sterba dsterba@suse.com Cc: Josef Bacik josef@toxicpanda.com Cc: Andreas Gruenbacher agruenba@redhat.com Cc: Will Deacon will@kernel.org Cc: Matthew Wilcox willy@infradead.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/btrfs/ioctl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/btrfs/ioctl.c~btrfs-avoid-live-lock-in-search_ioctl-on-hardware-with-sub-page-faults +++ a/fs/btrfs/ioctl.c @@ -2225,7 +2225,8 @@ static noinline int search_ioctl(struct

while (1) { ret = -EFAULT; - if (fault_in_writeable(ubuf + sk_offset, *buf_size - sk_offset)) + if (fault_in_exact_writeable(ubuf + sk_offset, + *buf_size - sk_offset)) break;

ret = btrfs_search_forward(root, &key, path, sk->min_transid); _

Patches currently in -mm which might be from catalin.marinas@arm.com are