xfs_trans_roll() loses the NOFS allocation context on the error path,
causing a circular lock dependency between xfs_nondir_ilock_class and
fs_reclaim reported by syzbot.  Fix this by transferring the nofs
context from the old transaction to the new one in xfs_trans_dup(),
so it remains active regardless of commit success or failure.

v2:
  - Instead of moving xfs_trans_set_context() before the error check,
    transfer the nofs context in xfs_trans_dup() via a new
    memalloc_flags_move() helper, as suggested by Darrick.
  - Change t_pflags from unsigned long to unsigned int to match mm API.

v1: https://lore.kernel.org/all/20260713035505.1635191-1-yun.zhou@windriver.com/T/

Yun Zhou (2):
  mm: introduce memalloc_flags_move() for transferring allocation scopes
  xfs: restore nofs context unconditionally in xfs_trans_roll

 fs/xfs/xfs_trans.c       |  9 +++------
 fs/xfs/xfs_trans.h       |  2 +-
 include/linux/sched/mm.h | 17 +++++++++++++++++
 3 files changed, 21 insertions(+), 7 deletions(-)

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2.43.0