| Message ID | 20221116102659.70287-13-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O long-term pinning) | expand |
On Wed, Nov 16, 2022 at 11:26:51AM +0100, David Hildenbrand wrote: > GUP now supports reliable R/O long-term pinning in COW mappings, such > that we break COW early. MAP_SHARED VMAs only use the shared zeropage so > far in one corner case (DAXFS file with holes), which can be ignored > because GUP does not support long-term pinning in fsdax (see > check_vma_flags()). > > Consequently, FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM is no longer required > for reliable R/O long-term pinning: FOLL_LONGTERM is sufficient. So stop > using FOLL_FORCE, which is really only for ptrace access. > > Cc: Bernard Metzler <bmt@zurich.ibm.com> > Cc: Jason Gunthorpe <jgg@ziepe.ca> > Cc: Leon Romanovsky <leon@kernel.org> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > drivers/infiniband/sw/siw/siw_mem.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Jason
diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c index 61c17db70d65..b2b33dd3b4fa 100644 --- a/drivers/infiniband/sw/siw/siw_mem.c +++ b/drivers/infiniband/sw/siw/siw_mem.c @@ -368,7 +368,7 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable) struct mm_struct *mm_s; u64 first_page_va; unsigned long mlock_limit; - unsigned int foll_flags = FOLL_WRITE; + unsigned int foll_flags = FOLL_LONGTERM; int num_pages, num_chunks, i, rv = 0; if (!can_do_mlock()) @@ -391,8 +391,8 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable) mmgrab(mm_s); - if (!writable) - foll_flags |= FOLL_FORCE; + if (writable) + foll_flags |= FOLL_WRITE; mmap_read_lock(mm_s); @@ -423,8 +423,7 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable) while (nents) { struct page **plist = &umem->page_chunk[i].plist[got]; - rv = pin_user_pages(first_page_va, nents, - foll_flags | FOLL_LONGTERM, + rv = pin_user_pages(first_page_va, nents, foll_flags, plist, NULL); if (rv < 0) goto out_sem_up;
GUP now supports reliable R/O long-term pinning in COW mappings, such that we break COW early. MAP_SHARED VMAs only use the shared zeropage so far in one corner case (DAXFS file with holes), which can be ignored because GUP does not support long-term pinning in fsdax (see check_vma_flags()). Consequently, FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM is no longer required for reliable R/O long-term pinning: FOLL_LONGTERM is sufficient. So stop using FOLL_FORCE, which is really only for ptrace access. Cc: Bernard Metzler <bmt@zurich.ibm.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Leon Romanovsky <leon@kernel.org> Signed-off-by: David Hildenbrand <david@redhat.com> --- drivers/infiniband/sw/siw/siw_mem.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)