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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 2E955C2D0A3 for ; Mon, 2 Nov 2020 01:07:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E67CE206E5 for ; Mon, 2 Nov 2020 01:07:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604279245; bh=ka5xjbfpq5X+yy69PexjPHyqZDsQG07VUHHeWKKGtf4=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=W5NgU1/SHmfh7XAASEOI05wSRFuMHj5I9UTb/qKQtS1FKv5fejuf8a8C1qOPPkKI5 64vyp5opOHKuMV9nvBuIB1kBlouuuEB+PCTSrTBJacJ+T1Bl0JbJTpeDr0N4E7XrPi QfyQrF5aQobdjl/aspUCvaLpf5WG+dlqW9vV4Paw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727367AbgKBBHZ (ORCPT ); Sun, 1 Nov 2020 20:07:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:48644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727335AbgKBBHZ (ORCPT ); Sun, 1 Nov 2020 20:07:25 -0500 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1E57B206A4; Mon, 2 Nov 2020 01:07:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604279244; bh=ka5xjbfpq5X+yy69PexjPHyqZDsQG07VUHHeWKKGtf4=; h=Date:From:To:Subject:In-Reply-To:From; b=LqFLx2rGcGVkQ2cQL1mP8BI0YPB2huIiixDBi9qfKe+ZYSjDpxcSBU5jQhfVHSr0M ga2RAlfjKLS149Mpo7Ed37VTc1AambzI3TtI7MJP4kM6i043RnThObC7TMV0Isv9gr 68wherUznXpvsE1NDpbWGXt7X7/9JQOnRLhwzjxY= Date: Sun, 01 Nov 2020 17:07:23 -0800 From: Andrew Morton To: akpm@linux-foundation.org, aneesh.kumar@linux.ibm.com, dan.j.williams@intel.com, hch@lst.de, ira.weiny@intel.com, jgg@mellanox.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, rcampbell@nvidia.com, sachinp@linux.vnet.ibm.com, torvalds@linux-foundation.org Subject: [patch 01/15] mm/mremap_pages: fix static key devmap_managed_key updates Message-ID: <20201102010723.iGXwcvhDY%akpm@linux-foundation.org> In-Reply-To: <20201101170656.48abbd5e88375219f868af5e@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: Ralph Campbell Subject: mm/mremap_pages: fix static key devmap_managed_key updates commit 6f42193fd86e ("memremap: don't use a separate devm action for devmap_managed_enable_get") changed the static key updates such that we now call devmap_managed_enable_put() without doing the equivalent devmap_managed_enable_get(). devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap types too. This results in the below warning when switching between system-ram and devdax mode for devdax namespace. jump label: negative count! WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0 Modules linked in: .... NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0 LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0 Call Trace: [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0 [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0 [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500 [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50 [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0 [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280 [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210 [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530 [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0 [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50 [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0 [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280 [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170 [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60 [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0 [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280 [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0 [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140 [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270 [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c Link: https://lkml.kernel.org/r/20201023183222.13186-1-rcampbell@nvidia.com Signed-off-by: Ralph Campbell Reported-by: Aneesh Kumar K.V Reviewed-by: Aneesh Kumar K.V Reviewed-by: Ira Weiny Tested-by: Sachin Sant Reviewed-by: Christoph Hellwig Cc: Dan Williams Cc: Jason Gunthorpe Signed-off-by: Andrew Morton --- mm/memremap.c | 39 ++++++++++++++++----------------------- 1 file changed, 16 insertions(+), 23 deletions(-) --- a/mm/memremap.c~mm-mremap_pages-fix-static-key-devmap_managed_key-updates +++ a/mm/memremap.c @@ -41,28 +41,24 @@ EXPORT_SYMBOL_GPL(memremap_compat_align) DEFINE_STATIC_KEY_FALSE(devmap_managed_key); EXPORT_SYMBOL(devmap_managed_key); -static void devmap_managed_enable_put(void) +static void devmap_managed_enable_put(struct dev_pagemap *pgmap) { - static_branch_dec(&devmap_managed_key); + if (pgmap->type == MEMORY_DEVICE_PRIVATE || + pgmap->type == MEMORY_DEVICE_FS_DAX) + static_branch_dec(&devmap_managed_key); } -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) +static void devmap_managed_enable_get(struct dev_pagemap *pgmap) { - if (pgmap->type == MEMORY_DEVICE_PRIVATE && - (!pgmap->ops || !pgmap->ops->page_free)) { - WARN(1, "Missing page_free method\n"); - return -EINVAL; - } - - static_branch_inc(&devmap_managed_key); - return 0; + if (pgmap->type == MEMORY_DEVICE_PRIVATE || + pgmap->type == MEMORY_DEVICE_FS_DAX) + static_branch_inc(&devmap_managed_key); } #else -static int devmap_managed_enable_get(struct dev_pagemap *pgmap) +static void devmap_managed_enable_get(struct dev_pagemap *pgmap) { - return -EINVAL; } -static void devmap_managed_enable_put(void) +static void devmap_managed_enable_put(struct dev_pagemap *pgmap) { } #endif /* CONFIG_DEV_PAGEMAP_OPS */ @@ -169,7 +165,7 @@ void memunmap_pages(struct dev_pagemap * pageunmap_range(pgmap, i); WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n"); - devmap_managed_enable_put(); + devmap_managed_enable_put(pgmap); } EXPORT_SYMBOL_GPL(memunmap_pages); @@ -307,7 +303,6 @@ void *memremap_pages(struct dev_pagemap .pgprot = PAGE_KERNEL, }; const int nr_range = pgmap->nr_range; - bool need_devmap_managed = true; int error, i; if (WARN_ONCE(!nr_range, "nr_range must be specified\n")) @@ -323,6 +318,10 @@ void *memremap_pages(struct dev_pagemap WARN(1, "Missing migrate_to_ram method\n"); return ERR_PTR(-EINVAL); } + if (!pgmap->ops->page_free) { + WARN(1, "Missing page_free method\n"); + return ERR_PTR(-EINVAL); + } if (!pgmap->owner) { WARN(1, "Missing owner\n"); return ERR_PTR(-EINVAL); @@ -336,11 +335,9 @@ void *memremap_pages(struct dev_pagemap } break; case MEMORY_DEVICE_GENERIC: - need_devmap_managed = false; break; case MEMORY_DEVICE_PCI_P2PDMA: params.pgprot = pgprot_noncached(params.pgprot); - need_devmap_managed = false; break; default: WARN(1, "Invalid pgmap type %d\n", pgmap->type); @@ -364,11 +361,7 @@ void *memremap_pages(struct dev_pagemap } } - if (need_devmap_managed) { - error = devmap_managed_enable_get(pgmap); - if (error) - return ERR_PTR(error); - } + devmap_managed_enable_get(pgmap); /* * Clear the pgmap nr_range as it will be incremented for each _