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=-9.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 BBE3EC388F9 for ; Fri, 23 Oct 2020 06:46:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C42BB22253 for ; Fri, 23 Oct 2020 06:46:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="rr6gPWvo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C42BB22253 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CC8AB6B0068; Fri, 23 Oct 2020 02:46:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C7A026B006C; Fri, 23 Oct 2020 02:46:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B69356B006E; Fri, 23 Oct 2020 02:46:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0154.hostedemail.com [216.40.44.154]) by kanga.kvack.org (Postfix) with ESMTP id 898196B0068 for ; Fri, 23 Oct 2020 02:46:33 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 277498B5B354 for ; Fri, 23 Oct 2020 06:46:33 +0000 (UTC) X-FDA: 77402256666.24.paper01_0c097dd27257 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id 049191A4A0 for ; Fri, 23 Oct 2020 06:46:33 +0000 (UTC) X-HE-Tag: paper01_0c097dd27257 X-Filterd-Recvd-Size: 6815 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Fri, 23 Oct 2020 06:46:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=3Zl0rvw/qJiKPxvEy3tqCZ3HJK8WyPTbT7XwamJFSaI=; b=rr6gPWvoN9S4AOg+TyKLYaGM3d LMw71ZZ60yc2agUfvIQOxbtcESBDo56obTsheeYUCAdW/g4FNZelg8wfaTVeyGxNJX58CVawinboC jdBhcD12BCUyA41Etq0vQ8oulE4vU1tL9L0vPykeNMTUWWi7v4qrwPURxGF1iCWww0+UIP214JQXo UKqM9T2y7G5Pr40dulT/ZzzVzuNLqjl8+8aoczuStfw8wK2OMVHJZqHxCPbqgWgUBboIoqmJfJxA7 ToATrTdrYw6O0IOwZHxycZOo+QlptP+rRNzySE3H8bQgoyJg5ewJBXoZgdBwXDlG1YNZXKrqpZEom mUtdZMuw==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kVqq2-0005yw-W4; Fri, 23 Oct 2020 06:46:11 +0000 Date: Fri, 23 Oct 2020 07:46:10 +0100 From: Christoph Hellwig To: Ralph Campbell Cc: Ira Weiny , "Aneesh Kumar K.V" , linux-mm@kvack.org, akpm@linux-foundation.org, Christoph Hellwig , Dan Williams , Sachin Sant , linux-nvdimm@lists.01.org, Jason Gunthorpe Subject: Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Message-ID: <20201023064610.GA22405@infradead.org> References: <20201022060753.21173-1-aneesh.kumar@linux.ibm.com> <20201022154124.GA537138@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html 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 11:19:43AM -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?