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dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 761A76B0062; Fri, 23 Oct 2020 13:29:49 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 712376B0068; Fri, 23 Oct 2020 13:29:49 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5DA146B006C; Fri, 23 Oct 2020 13:29:49 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0079.hostedemail.com [216.40.44.79]) by kanga.kvack.org (Postfix) with ESMTP id 2D66E6B0062 for ; Fri, 23 Oct 2020 13:29:49 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id B39698249980 for ; Fri, 23 Oct 2020 17:29:48 +0000 (UTC) X-FDA: 77403877656.03.blood58_18148f82725b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin03.hostedemail.com (Postfix) with ESMTP id 9456628A4EB for ; Fri, 23 Oct 2020 17:29:48 +0000 (UTC) X-HE-Tag: blood58_18148f82725b X-Filterd-Recvd-Size: 7388 Received: from hqnvemgate25.nvidia.com (hqnvemgate25.nvidia.com [216.228.121.64]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Fri, 23 Oct 2020 17:29:47 +0000 (UTC) Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Fri, 23 Oct 2020 10:29:52 -0700 Received: from rcampbell-dev.nvidia.com (172.20.13.39) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 23 Oct 2020 17:29:36 +0000 Subject: Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates To: Christoph Hellwig CC: Ira Weiny , Aneesh Kumar K.V , , , Dan Williams , "Sachin Sant" , , "Jason Gunthorpe" References: <20201022060753.21173-1-aneesh.kumar@linux.ibm.com> <20201022154124.GA537138@iweiny-DESK2.sc.intel.com> <20201023064610.GA22405@infradead.org> X-Nvconfidentiality: public From: Ralph Campbell Message-ID: Date: Fri, 23 Oct 2020 10:29:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20201023064610.GA22405@infradead.org> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1603474192; bh=YyKQoCN1wnU7okhj6LDaueejqYWF4Ww+dZnQEYDI7FU=; h=Subject:To:CC:References:X-Nvconfidentiality:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:Content-Type:Content-Language: Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy; b=i4hqGAM3uBnsXS2G1O8qT7iA6eQW47llgBWKgIEDDQWpPNJvsHh9/qJPPQIUbO4lt Ob3BUjLwnu6G6MuyKQJYl8nABl1hrGBRGFrD7+JoF4D4UI3MaB754PfSKa2N2ftVFn /2N8C8SdJTQ5GdDrUEf+Qd2xmyf4uaaQB7esRXfJWgV20Gpe8CF9UOMdxG4bS5O02t S9PS317sSp1CxG4nYIWLduoLmm/2XKvppjFg1iBRvIORzh3cmWpabZVxXeQNV6WlV4 88L75tlC7jUaQtlj2YLaV+54zPJE5p7pleBEfs5LyZRaEepJiCSySBz6pTLyYYcRrO Q6CnBm7NNUwcw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/22/20 11:46 PM, Christoph Hellwig wrote: > On Thu, Oct 22, 2020 at 11:19:43AM -0700, Ralph Campbell wrote: >> >> On 10/22/20 8:41 AM, Ira Weiny wrote: >>> On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote: >>>> 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 (unreliable) >>>> [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 >>>> >>>> Cc: Christoph Hellwig >>>> Cc: Dan Williams >>>> Cc: Sachin Sant >>>> Cc: linux-nvdimm@lists.01.org >>>> Cc: Ira Weiny >>>> Cc: Jason Gunthorpe >>>> Signed-off-by: Aneesh Kumar K.V >>>> --- >>>> mm/memremap.c | 19 +++++++++++++++---- >>>> 1 file changed, 15 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/mm/memremap.c b/mm/memremap.c >>>> index 73a206d0f645..d4402ff3e467 100644 >>>> --- a/mm/memremap.c >>>> +++ b/mm/memremap.c >>>> @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap) >>>> { >>>> unsigned long pfn; >>>> int i; >>>> + bool need_devmap_managed = false; >>>> + >>>> + switch (pgmap->type) { >>>> + case MEMORY_DEVICE_PRIVATE: >>>> + case MEMORY_DEVICE_FS_DAX: >>>> + need_devmap_managed = true; >>>> + break; >>>> + default: >>>> + break; >>>> + } >>> >>> Is it overkill to avoid duplicating this switch logic in >>> page_is_devmap_managed() by creating another call which can be used here? >> >> Perhaps. I can imagine a helper defined in include/linux/mm.h which >> page_is_devmap_managed() could also call but that would impact a lot of >> places that include mm.h. Since memremap.c already has to have intimate >> knowledge of the pgmap->type, I think limiting the change to just what >> is needed is better for now. So the patch looks OK to me. >> >> Looking at this some more, I would suggest changing devmap_managed_enable_get() >> and devmap_managed_enable_put() to do the special case checking instead of >> doing it in memremap_pages() and memunmap_pages(). >> Then devmap_managed_enable_get() doesn't need to return an error if >> CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the >> following. >> >> Signed-off-by: Ralph Campbell > > This looks ok as well. Can you submit it as a proper standalone patch? > Yes. I was just about to ask whether I should do that and you beat me to it.