Andrew, I'm very sorry, this is so late: I thought we had already
tested 5.12-rc's mm/filemap changes earlier, but running xfstests
on 32-bit huge tmpfs last weekend revealed a hang (fixed in 1/2);
then looking closer at test results, found SEEK_HOLE/SEEK_DATA
discrepancies that I'd previously assumed benign (surprises there
not surprising when huge pages get used) were in fact indicating
regressions in the new seek_hole_data implementation (fixed in 2/2).

Complicated by xfstests' seek_sanity_test needing some adjustments
to work correctly on huge tmpfs; but not yet submitted because I've
more to do there.  seek_sanity combo patch attached, to allow anyone
here to verify the fixes on generic 308 285 286 436 445 448 490 539.

Up to you and Matthew whether these are rushed last minute into
5.12, or held over until the merge window, adding "Cc: stable"s.

1/2 mm/filemap: fix find_lock_entries hang on 32-bit THP
2/2 mm/filemap: fix mapping_seek_hole_data on THP & 32-bit

 mm/filemap.c |   33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

Thanks,
Hugh