From patchwork Tue Jan 15 18:13:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Davidlohr Bueso X-Patchwork-Id: 10764937 X-Patchwork-Delegate: jgg@ziepe.ca Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 43BFF14E5 for ; Tue, 15 Jan 2019 18:13:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 34BDE2D467 for ; Tue, 15 Jan 2019 18:13:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 28A742D4D8; Tue, 15 Jan 2019 18:13:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BE2FB2D4AD for ; Tue, 15 Jan 2019 18:13:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731305AbfAOSNl (ORCPT ); Tue, 15 Jan 2019 13:13:41 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:53218 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731235AbfAOSNl (ORCPT ); Tue, 15 Jan 2019 13:13:41 -0500 Received: from localhost.localdomain (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by smtp2.provo.novell.com with ESMTP (TLS encrypted); Tue, 15 Jan 2019 11:13:32 -0700 From: Davidlohr Bueso To: akpm@linux-foundation.org Cc: dledford@redhat.com, jgg@mellanox.com, linux-rdma@vger.kernel.org, linux-mm@kvack.org, dave@stgolabs.net, Davidlohr Bueso Subject: [PATCH 6/6] drivers/IB,core: reduce scope of mmap_sem Date: Tue, 15 Jan 2019 10:13:00 -0800 Message-Id: <20190115181300.27547-7-dave@stgolabs.net> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190115181300.27547-1-dave@stgolabs.net> References: <20190115181300.27547-1-dave@stgolabs.net> Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP ib_umem_get() uses gup_longterm() and relies on the lock to stabilze the vma_list, so we cannot really get rid of mmap_sem altogether, but now that the counter is atomic, we can get of some complexity that mmap_sem brings with only pinned_vm. Signed-off-by: Davidlohr Bueso Reviewed-by: Ira Weiny --- drivers/infiniband/core/umem.c | 41 ++--------------------------------------- 1 file changed, 2 insertions(+), 39 deletions(-) diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c index bf556215aa7e..baa2412bf6fb 100644 --- a/drivers/infiniband/core/umem.c +++ b/drivers/infiniband/core/umem.c @@ -160,15 +160,12 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; - down_write(&mm->mmap_sem); - new_pinned = atomic_long_read(&mm->pinned_vm) + npages; + new_pinned = atomic_long_add_return(npages, &mm->pinned_vm); if (new_pinned > lock_limit && !capable(CAP_IPC_LOCK)) { - up_write(&mm->mmap_sem); + atomic_long_sub(npages, &mm->pinned_vm); ret = -ENOMEM; goto out; } - atomic_long_set(&mm->pinned_vm, new_pinned); - up_write(&mm->mmap_sem); cur_base = addr & PAGE_MASK; @@ -228,9 +225,7 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr, umem_release: __ib_umem_release(context->device, umem, 0); vma: - down_write(&mm->mmap_sem); atomic_long_sub(ib_umem_num_pages(umem), &mm->pinned_vm); - up_write(&mm->mmap_sem); out: if (vma_list) free_page((unsigned long) vma_list); @@ -253,25 +248,12 @@ static void __ib_umem_release_tail(struct ib_umem *umem) kfree(umem); } -static void ib_umem_release_defer(struct work_struct *work) -{ - struct ib_umem *umem = container_of(work, struct ib_umem, work); - - down_write(&umem->owning_mm->mmap_sem); - atomic_long_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm); - up_write(&umem->owning_mm->mmap_sem); - - __ib_umem_release_tail(umem); -} - /** * ib_umem_release - release memory pinned with ib_umem_get * @umem: umem struct to release */ void ib_umem_release(struct ib_umem *umem) { - struct ib_ucontext *context = umem->context; - if (umem->is_odp) { ib_umem_odp_release(to_ib_umem_odp(umem)); __ib_umem_release_tail(umem); @@ -280,26 +262,7 @@ void ib_umem_release(struct ib_umem *umem) __ib_umem_release(umem->context->device, umem, 1); - /* - * We may be called with the mm's mmap_sem already held. This - * can happen when a userspace munmap() is the call that drops - * the last reference to our file and calls our release - * method. If there are memory regions to destroy, we'll end - * up here and not be able to take the mmap_sem. In that case - * we defer the vm_locked accounting a workqueue. - */ - if (context->closing) { - if (!down_write_trylock(&umem->owning_mm->mmap_sem)) { - INIT_WORK(&umem->work, ib_umem_release_defer); - queue_work(ib_wq, &umem->work); - return; - } - } else { - down_write(&umem->owning_mm->mmap_sem); - } atomic_long_sub(ib_umem_num_pages(umem), &umem->owning_mm->pinned_vm); - up_write(&umem->owning_mm->mmap_sem); - __ib_umem_release_tail(umem); } EXPORT_SYMBOL(ib_umem_release);