| Message ID | 20221107161740.144456-11-david@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/gup: remove FOLL_FORCE usage from drivers (reliable R/O long-term pinning) | expand |
On Mon, Nov 07, 2022 at 05:17:31PM +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 debugger access. > > Cc: Jason Gunthorpe <jgg@ziepe.ca> > Cc: Leon Romanovsky <leon@kernel.org> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > drivers/infiniband/core/umem.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) Thanks, Tested-by: Leon Romanovsky <leonro@nvidia.com> # Over mlx4 and mlx5.
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index 86d479772fbc..755a9c57db6f 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -156,7 +156,7 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr, struct mm_struct *mm; unsigned long npages; int pinned, ret; - unsigned int gup_flags = FOLL_WRITE; + unsigned int gup_flags = FOLL_LONGTERM; /* * If the combination of the addr and size requested for this memory @@ -210,8 +210,8 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr, cur_base = addr & PAGE_MASK; - if (!umem->writable) - gup_flags |= FOLL_FORCE; + if (umem->writable) + gup_flags |= FOLL_WRITE; while (npages) { cond_resched(); @@ -219,7 +219,7 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr, min_t(unsigned long, npages, PAGE_SIZE / sizeof(struct page *)), - gup_flags | FOLL_LONGTERM, page_list); + gup_flags, page_list); if (pinned < 0) { ret = pinned; goto umem_release;
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 debugger access. Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Leon Romanovsky <leon@kernel.org> Signed-off-by: David Hildenbrand <david@redhat.com> --- drivers/infiniband/core/umem.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)