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Thu, 22 Oct 2020 06:08:23 GMT Received: from b01cxnp23034.gho.pok.ibm.com (b01cxnp23034.gho.pok.ibm.com [9.57.198.29]) by ppma03dal.us.ibm.com with ESMTP id 347r89q612-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 22 Oct 2020 06:08:23 +0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 09M68MS653871006 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 22 Oct 2020 06:08:22 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B1B71112066; Thu, 22 Oct 2020 06:08:22 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9E1F2112062; Thu, 22 Oct 2020 06:08:13 +0000 (GMT) Received: from skywalker.ibmuc.com (unknown [9.77.198.168]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 22 Oct 2020 06:08:12 +0000 (GMT) From: "Aneesh Kumar K.V" To: linux-mm@kvack.org Cc: akpm@linux-foundation.org, "Aneesh Kumar K.V" , Christoph Hellwig , Dan Williams , Sachin Sant , linux-nvdimm@lists.01.org, Ira Weiny , Jason Gunthorpe Subject: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Date: Thu, 22 Oct 2020 11:37:53 +0530 Message-Id: <20201022060753.21173-1-aneesh.kumar@linux.ibm.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.737 definitions=2020-10-22_02:2020-10-20,2020-10-22 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxlogscore=999 clxscore=1011 priorityscore=1501 mlxscore=0 phishscore=0 bulkscore=0 suspectscore=3 spamscore=0 adultscore=0 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010220040 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: 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 Tested-by: Sachin Sant Reviewed-by: Christoph Hellwig Signed-off-by: Ralph Campbell Reviewed-by: Ira Weiny Reviewed-by: Aneesh Kumar K.V Tested-by: Sachin Sant --- 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; + } 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; 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);