Hi I suggest to join memalloc_noio and memalloc_nofs into just one flag that prevents both filesystem recursion and i/o recursion.
Note that any I/O can recurse into a filesystem via the loop device, thus it doesn't make much sense to have a context where PF_MEMALLOC_NOFS is set and PF_MEMALLOC_NOIO is not set. Mikulas On Thu, 25 Jun 2020, Matthew Wilcox (Oracle) wrote: > I want a memalloc_nowait like we have memalloc_noio and memalloc_nofs > for an upcoming patch series, and Jens also wants it for non-blocking > io_uring. It turns out we already have dm-bufio which could benefit > from memalloc_nowait, so it may as well go into the tree now. > > The biggest problem is that we're basically out of PF_ flags, so we need > to find somewhere else to store the PF_MEMALLOC_NOWAIT flag. It turns > out the PF_ flags are really supposed to be used for flags which are > accessed from other tasks, and the MEMALLOC flags are only going to > be used by this task. So shuffling everything around frees up some PF > flags and generally makes the world a better place. > > Patch series also available from > http://git.infradead.org/users/willy/linux.git/shortlog/refs/heads/memalloc > > Matthew Wilcox (Oracle) (6): > mm: Replace PF_MEMALLOC_NOIO with memalloc_noio > mm: Add become_kswapd and restore_kswapd > xfs: Convert to memalloc_nofs_save > mm: Replace PF_MEMALLOC_NOFS with memalloc_nofs > mm: Replace PF_MEMALLOC_NOIO with memalloc_nocma > mm: Add memalloc_nowait > > drivers/block/loop.c | 3 +- > drivers/md/dm-bufio.c | 30 ++++-------- > drivers/md/dm-zoned-metadata.c | 5 +- > fs/iomap/buffered-io.c | 2 +- > fs/xfs/kmem.c | 2 +- > fs/xfs/libxfs/xfs_btree.c | 14 +++--- > fs/xfs/xfs_aops.c | 4 +- > fs/xfs/xfs_buf.c | 2 +- > fs/xfs/xfs_linux.h | 6 --- > fs/xfs/xfs_trans.c | 14 +++--- > fs/xfs/xfs_trans.h | 2 +- > include/linux/sched.h | 7 +-- > include/linux/sched/mm.h | 84 ++++++++++++++++++++++++++-------- > kernel/sys.c | 8 ++-- > mm/vmscan.c | 16 +------ > 15 files changed, 105 insertions(+), 94 deletions(-) > > -- > 2.27.0 >
