On Tue, Feb 01, 2022 at 02:11:08AM -0800, John Hubbard wrote: > There is only one caller of get_user_pages_locked(). The purpose of > get_user_pages_locked() is to allow for unlocking the mmap_lock when > reading a page from the disk during a page fault (hidden behind > VM_FAULT_RETRY). The idea is to reduce contention on the heavily-used > mmap_lock. (Thanks to Jan Kara for clearly pointing that out, and in > fact I've used some of his wording here.) > > However, it is unlikely for lookup_node() to take a page fault. With > that in mind, change over to calling get_user_pages_fast(). This > simplifies the code, runs a little faster in the expected case, and > allows removing get_user_pages_locked() entirely. > > Cc: Jan Kara <jack@xxxxxxx> > Suggested-by: Jason Gunthorpe <jgg@xxxxxxxx> > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> > --- > include/linux/mm.h | 2 -- > mm/gup.c | 59 ---------------------------------------------- > mm/mempolicy.c | 21 +++++++---------- > 3 files changed, 9 insertions(+), 73 deletions(-) Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx> Jason
