Thanks for cleaning this up, will make any potential follow on I do
much easier. Feel free to add:
Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx>
Bernard Metzler <bmt@xxxxxxxxxxxxxx> writes:
> To avoid racing with other user memory reservations, immediately
> account full amount of pages to be pinned.
>
> Fixes: 2251334dcac9 ("rdma/siw: application buffer management")
> Reported-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Suggested-by: Alistair Popple <apopple@xxxxxxxxxx>
> Signed-off-by: Bernard Metzler <bmt@xxxxxxxxxxxxxx>
> ---
> drivers/infiniband/sw/siw/siw_mem.c | 23 ++++++++++++-----------
> 1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
> index b2b33dd3b4fa..f51ab2ccf151 100644
> --- a/drivers/infiniband/sw/siw/siw_mem.c
> +++ b/drivers/infiniband/sw/siw/siw_mem.c
> @@ -398,7 +398,7 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
>
> mlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
>
> - if (num_pages + atomic64_read(&mm_s->pinned_vm) > mlock_limit) {
> + if (atomic64_add_return(num_pages, &mm_s->pinned_vm) > mlock_limit) {
> rv = -ENOMEM;
> goto out_sem_up;
> }
> @@ -411,30 +411,27 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
> goto out_sem_up;
> }
> for (i = 0; num_pages; i++) {
> - int got, nents = min_t(int, num_pages, PAGES_PER_CHUNK);
> -
> - umem->page_chunk[i].plist =
> + int nents = min_t(int, num_pages, PAGES_PER_CHUNK);
> + struct page **plist =
> kcalloc(nents, sizeof(struct page *), GFP_KERNEL);
> - if (!umem->page_chunk[i].plist) {
> +
> + if (!plist) {
> rv = -ENOMEM;
> goto out_sem_up;
> }
> - got = 0;
> + umem->page_chunk[i].plist = plist;
> while (nents) {
> - struct page **plist = &umem->page_chunk[i].plist[got];
> -
> rv = pin_user_pages(first_page_va, nents, foll_flags,
> plist, NULL);
> if (rv < 0)
> goto out_sem_up;
>
> umem->num_pages += rv;
> - atomic64_add(rv, &mm_s->pinned_vm);
> first_page_va += rv * PAGE_SIZE;
> + plist += rv;
> nents -= rv;
> - got += rv;
> + num_pages -= rv;
> }
> - num_pages -= got;
> }
> out_sem_up:
> mmap_read_unlock(mm_s);
> @@ -442,6 +439,10 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
> if (rv > 0)
> return umem;
>
> + /* Adjust accounting for pages not pinned */
> + if (num_pages)
> + atomic64_sub(num_pages, &mm_s->pinned_vm);
> +
> siw_umem_release(umem, false);
>
> return ERR_PTR(rv);
