From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 179E0C11F66 for ; Thu, 1 Jul 2021 01:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 037596141A for ; Thu, 1 Jul 2021 01:54:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238505AbhGAB4x (ORCPT ); Wed, 30 Jun 2021 21:56:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:46756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238429AbhGAB4w (ORCPT ); Wed, 30 Jun 2021 21:56:52 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E12E96146D; Thu, 1 Jul 2021 01:54:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1625104463; bh=6Pji3cq4i9A9CHhjXB2IEQFixwrlJYwoxrsU8PnJmPs=; h=Date:From:To:Subject:In-Reply-To:From; b=Az/a3r2eq3VcZvK3iLX/T5N4nM28HBIlDAIuiT3L+YrmJxHQ3S5wLW6kdVfyCsBxk GyvlR6NHOxZlAAOp4LZImFeBZDj3creGwfXShSx7dXHf/k/QENMjdIbRp9z3+kNxKN J9AEj4ixgJzwvADxBf8u8rXHowu8fyuAiGHbxWvM= Date: Wed, 30 Jun 2021 18:54:22 -0700 From: Andrew Morton To: akpm@linux-foundation.org, apopple@nvidia.com, bskeggs@redhat.com, hch@lst.de, hughd@google.com, jgg@nvidia.com, jhubbard@nvidia.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, peterx@redhat.com, rcampbell@nvidia.com, shakeelb@google.com, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 135/192] mm/memory.c: allow different return codes for copy_nonpresent_pte() Message-ID: <20210701015422.fnRcl9cvh%akpm@linux-foundation.org> In-Reply-To: <20210630184624.9ca1937310b0dd5ce66b30e7@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Alistair Popple Subject: mm/memory.c: allow different return codes for copy_nonpresent_pte() Currently if copy_nonpresent_pte() returns a non-zero value it is assumed to be a swap entry which requires further processing outside the loop in copy_pte_range() after dropping locks. This prevents other values being returned to signal conditions such as failure which a subsequent change requires. Instead make copy_nonpresent_pte() return an error code if further processing is required and read the value for the swap entry in the main loop under the ptl. Link: https://lkml.kernel.org/r/20210616105937.23201-7-apopple@nvidia.com Signed-off-by: Alistair Popple Reviewed-by: Peter Xu Cc: Ben Skeggs Cc: Christoph Hellwig Cc: Hugh Dickins Cc: Jason Gunthorpe Cc: John Hubbard Cc: "Matthew Wilcox (Oracle)" Cc: Ralph Campbell Cc: Shakeel Butt Signed-off-by: Andrew Morton --- mm/memory.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) --- a/mm/memory.c~mm-memoryc-allow-different-return-codes-for-copy_nonpresent_pte +++ a/mm/memory.c @@ -717,7 +717,7 @@ copy_nonpresent_pte(struct mm_struct *ds if (likely(!non_swap_entry(entry))) { if (swap_duplicate(entry) < 0) - return entry.val; + return -EIO; /* make sure dst_mm is on swapoff's mmlist. */ if (unlikely(list_empty(&dst_mm->mmlist))) { @@ -973,12 +973,14 @@ again: continue; } if (unlikely(!pte_present(*src_pte))) { - entry.val = copy_nonpresent_pte(dst_mm, src_mm, - dst_pte, src_pte, - dst_vma, src_vma, - addr, rss); - if (entry.val) + ret = copy_nonpresent_pte(dst_mm, src_mm, + dst_pte, src_pte, + dst_vma, src_vma, + addr, rss); + if (ret == -EIO) { + entry = pte_to_swp_entry(*src_pte); break; + } progress += 8; continue; } @@ -1011,20 +1013,24 @@ again: pte_unmap_unlock(orig_dst_pte, dst_ptl); cond_resched(); - if (entry.val) { + if (ret == -EIO) { + VM_WARN_ON_ONCE(!entry.val); if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) { ret = -ENOMEM; goto out; } entry.val = 0; - } else if (ret) { - WARN_ON_ONCE(ret != -EAGAIN); + } else if (ret == -EAGAIN) { prealloc = page_copy_prealloc(src_mm, src_vma, addr); if (!prealloc) return -ENOMEM; - /* We've captured and resolved the error. Reset, try again. */ - ret = 0; + } else if (ret) { + VM_WARN_ON_ONCE(1); } + + /* We've captured and resolved the error. Reset, try again. */ + ret = 0; + if (addr != end) goto again; out: _