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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 92EDEC55179 for ; Thu, 22 Oct 2020 15:41:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E711624640 for ; Thu, 22 Oct 2020 15:41:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E711624640 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DA6A06B0070; Thu, 22 Oct 2020 11:41:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D57116B0071; Thu, 22 Oct 2020 11:41:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BF82A6B0073; Thu, 22 Oct 2020 11:41:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0023.hostedemail.com [216.40.44.23]) by kanga.kvack.org (Postfix) with ESMTP id 91F7A6B0070 for ; Thu, 22 Oct 2020 11:41:31 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 26F0B180AD81A for ; Thu, 22 Oct 2020 15:41:31 +0000 (UTC) X-FDA: 77399975982.16.river98_3500f5a27252 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id EC99110273510 for ; Thu, 22 Oct 2020 15:41:30 +0000 (UTC) X-HE-Tag: river98_3500f5a27252 X-Filterd-Recvd-Size: 6949 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Thu, 22 Oct 2020 15:41:29 +0000 (UTC) IronPort-SDR: hBeQNZzAJgsMrNpnPcmyDnEkRMVxAO8Ge2ET9QfOmfGhg7BersRCpKZdA5nE7S1QzyVTkfWKGm j8Wmj0C1Aygg== X-IronPort-AV: E=McAfee;i="6000,8403,9781"; a="167643038" X-IronPort-AV: E=Sophos;i="5.77,404,1596524400"; d="scan'208";a="167643038" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Oct 2020 08:41:26 -0700 IronPort-SDR: 1uNh9uMV4kVTPyhJoPRnk70kap5HaSBV3cpUlNni76LkNQIPkUaUd8Juxy7z9qjPb7Jx3xXh0/ ifXUwI6+s4RQ== X-IronPort-AV: E=Sophos;i="5.77,404,1596524400"; d="scan'208";a="524320271" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Oct 2020 08:41:25 -0700 Date: Thu, 22 Oct 2020 08:41:24 -0700 From: Ira Weiny To: "Aneesh Kumar K.V" Cc: linux-mm@kvack.org, akpm@linux-foundation.org, Christoph Hellwig , Dan Williams , Sachin Sant , linux-nvdimm@lists.01.org, Jason Gunthorpe , Ralph Campbell Subject: Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Message-ID: <20201022154124.GA537138@iweiny-DESK2.sc.intel.com> References: <20201022060753.21173-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201022060753.21173-1-aneesh.kumar@linux.ibm.com> User-Agent: Mutt/1.11.1 (2018-12-01) 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 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? > > dev_pagemap_kill(pgmap); > for (i = 0; i < pgmap->nr_range; i++) > @@ -169,7 +179,8 @@ void memunmap_pages(struct dev_pagemap *pgmap) > pageunmap_range(pgmap, i); > > WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n"); > - devmap_managed_enable_put(); > + if (need_devmap_managed) > + devmap_managed_enable_put(); > } > EXPORT_SYMBOL_GPL(memunmap_pages); > > @@ -307,7 +318,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) > .pgprot = PAGE_KERNEL, > }; > const int nr_range = pgmap->nr_range; > - bool need_devmap_managed = true; > + bool need_devmap_managed = false; I'm CC'ing Ralph Campbell because I think some of his work has proposed this same change. Ira > int error, i; > > if (WARN_ONCE(!nr_range, "nr_range must be specified\n")) > @@ -327,6 +338,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) > WARN(1, "Missing owner\n"); > return ERR_PTR(-EINVAL); > } > + need_devmap_managed = true; > break; > case MEMORY_DEVICE_FS_DAX: > if (!IS_ENABLED(CONFIG_ZONE_DEVICE) || > @@ -334,13 +346,12 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid) > WARN(1, "File system DAX not supported\n"); > return ERR_PTR(-EINVAL); > } > + need_devmap_managed = true; > 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); > -- > 2.26.2 >