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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 05775C07520 for ; Thu, 13 Sep 2018 02:34:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3BA620882 for ; Thu, 13 Sep 2018 02:34:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A3BA620882 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727839AbeIMHlo (ORCPT ); Thu, 13 Sep 2018 03:41:44 -0400 Received: from mga07.intel.com ([134.134.136.100]:54548 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726399AbeIMHln (ORCPT ); Thu, 13 Sep 2018 03:41:43 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga105.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Sep 2018 19:34:22 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,367,1531810800"; d="scan'208";a="80036427" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by FMSMGA003.fm.intel.com with ESMTP; 12 Sep 2018 19:33:59 -0700 Subject: [PATCH v5 3/7] mm, devm_memremap_pages: Fix shutdown handling From: Dan Williams To: akpm@linux-foundation.org Cc: stable@vger.kernel.org, Christoph Hellwig , =?utf-8?b?SsOpcsO0bWU=?= Glisse , Logan Gunthorpe , Logan Gunthorpe , alexander.h.duyck@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Wed, 12 Sep 2018 19:22:17 -0700 Message-ID: <153680533706.453305.3428304103990941022.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <153680531988.453305.8080706591516037706.stgit@dwillia2-desk3.amr.corp.intel.com> References: <153680531988.453305.8080706591516037706.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-2-gc94f MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The last step before devm_memremap_pages() returns success is to allocate a release action, devm_memremap_pages_release(), to tear the entire setup down. However, the result from devm_add_action() is not checked. Checking the error from devm_add_action() is not enough. The api currently relies on the fact that the percpu_ref it is using is killed by the time the devm_memremap_pages_release() is run. Rather than continue this awkward situation, offload the responsibility of killing the percpu_ref to devm_memremap_pages_release() directly. This allows devm_memremap_pages() to do the right thing relative to init failures and shutdown. Without this change we could fail to register the teardown of devm_memremap_pages(). The likelihood of hitting this failure is tiny as small memory allocations almost always succeed. However, the impact of the failure is large given any future reconfiguration, or disable/enable, of an nvdimm namespace will fail forever as subsequent calls to devm_memremap_pages() will fail to setup the pgmap_radix since there will be stale entries for the physical address range. An argument could be made to require that the ->kill() operation be set in the @pgmap arg rather than passed in separately. However, it helps code readability, tracking the lifetime of a given instance, to be able to grep the kill routine directly at the devm_memremap_pages() call site. Cc: Fixes: e8d513483300 ("memremap: change devm_memremap_pages interface...") Cc: Christoph Hellwig Cc: "Jérôme Glisse" Reported-by: Logan Gunthorpe Reviewed-by: Logan Gunthorpe Signed-off-by: Dan Williams --- drivers/dax/pmem.c | 15 +++------------ drivers/nvdimm/pmem.c | 18 ++++++++---------- include/linux/memremap.h | 7 +++++-- kernel/memremap.c | 36 +++++++++++++++++++----------------- tools/testing/nvdimm/test/iomap.c | 21 ++++++++++++++++++--- 5 files changed, 53 insertions(+), 44 deletions(-) diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index 99e2aace8078..c1e03d769e6d 100644 --- a/drivers/dax/pmem.c +++ b/drivers/dax/pmem.c @@ -48,9 +48,8 @@ static void dax_pmem_percpu_exit(void *data) percpu_ref_exit(ref); } -static void dax_pmem_percpu_kill(void *data) +static void dax_pmem_percpu_kill(struct percpu_ref *ref) { - struct percpu_ref *ref = data; struct dax_pmem *dax_pmem = to_dax_pmem(ref); dev_dbg(dax_pmem->dev, "trace\n"); @@ -112,17 +111,9 @@ static int dax_pmem_probe(struct device *dev) } dax_pmem->pgmap.ref = &dax_pmem->ref; - addr = devm_memremap_pages(dev, &dax_pmem->pgmap); - if (IS_ERR(addr)) { - devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref); - percpu_ref_exit(&dax_pmem->ref); + addr = devm_memremap_pages(dev, &dax_pmem->pgmap, dax_pmem_percpu_kill); + if (IS_ERR(addr)) return PTR_ERR(addr); - } - - rc = devm_add_action_or_reset(dev, dax_pmem_percpu_kill, - &dax_pmem->ref); - if (rc) - return rc; /* adjust the dax_region resource to the start of data */ memcpy(&res, &dax_pmem->pgmap.res, sizeof(res)); diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 6071e2942053..c9cad5ebea5b 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -309,8 +309,11 @@ static void pmem_release_queue(void *q) blk_cleanup_queue(q); } -static void pmem_freeze_queue(void *q) +static void pmem_freeze_queue(struct percpu_ref *ref) { + struct request_queue *q; + + q = container_of(ref, typeof(*q), q_usage_counter); blk_freeze_queue_start(q); } @@ -405,7 +408,8 @@ static int pmem_attach_disk(struct device *dev, if (is_nd_pfn(dev)) { if (setup_pagemap_fsdax(dev, &pmem->pgmap)) return -ENOMEM; - addr = devm_memremap_pages(dev, &pmem->pgmap); + addr = devm_memremap_pages(dev, &pmem->pgmap, + pmem_freeze_queue); pfn_sb = nd_pfn->pfn_sb; pmem->data_offset = le64_to_cpu(pfn_sb->dataoff); pmem->pfn_pad = resource_size(res) - @@ -418,20 +422,14 @@ static int pmem_attach_disk(struct device *dev, pmem->pgmap.altmap_valid = false; if (setup_pagemap_fsdax(dev, &pmem->pgmap)) return -ENOMEM; - addr = devm_memremap_pages(dev, &pmem->pgmap); + addr = devm_memremap_pages(dev, &pmem->pgmap, + pmem_freeze_queue); pmem->pfn_flags |= PFN_MAP; memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res)); } else addr = devm_memremap(dev, pmem->phys_addr, pmem->size, ARCH_MEMREMAP_PMEM); - /* - * At release time the queue must be frozen before - * devm_memremap_pages is unwound - */ - if (devm_add_action_or_reset(dev, pmem_freeze_queue, q)) - return -ENOMEM; - if (IS_ERR(addr)) return PTR_ERR(addr); pmem->virt_addr = addr; diff --git a/include/linux/memremap.h b/include/linux/memremap.h index f91f9e763557..71f5e7c7dfb9 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -106,6 +106,7 @@ typedef void (*dev_page_free_t)(struct page *page, void *data); * @altmap: pre-allocated/reserved memory for vmemmap allocations * @res: physical address range covered by @ref * @ref: reference count that pins the devm_memremap_pages() mapping + * @kill: callback to transition @ref to the dead state * @dev: host device of the mapping for debug * @data: private data pointer for page_free() * @type: memory type: see MEMORY_* in memory_hotplug.h @@ -117,13 +118,15 @@ struct dev_pagemap { bool altmap_valid; struct resource res; struct percpu_ref *ref; + void (*kill)(struct percpu_ref *ref); struct device *dev; void *data; enum memory_type type; }; #ifdef CONFIG_ZONE_DEVICE -void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); +void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap, + void (*kill)(struct percpu_ref *)); struct dev_pagemap *get_dev_pagemap(unsigned long pfn, struct dev_pagemap *pgmap); @@ -131,7 +134,7 @@ unsigned long vmem_altmap_offset(struct vmem_altmap *altmap); void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns); #else static inline void *devm_memremap_pages(struct device *dev, - struct dev_pagemap *pgmap) + struct dev_pagemap *pgmap, void (*kill)(struct percpu_ref *)) { /* * Fail attempts to call devm_memremap_pages() without diff --git a/kernel/memremap.c b/kernel/memremap.c index 92e838127767..ab5eb570d28d 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -122,14 +122,10 @@ static void devm_memremap_pages_release(void *data) resource_size_t align_start, align_size; unsigned long pfn; + pgmap->kill(pgmap->ref); for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); - if (percpu_ref_tryget_live(pgmap->ref)) { - dev_WARN(dev, "%s: page mapping is still live!\n", __func__); - percpu_ref_put(pgmap->ref); - } - /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) @@ -150,7 +146,8 @@ static void devm_memremap_pages_release(void *data) /** * devm_memremap_pages - remap and provide memmap backing for the given resource * @dev: hosting device for @res - * @pgmap: pointer to a struct dev_pgmap + * @pgmap: pointer to a struct dev_pagemap + * @kill: routine to kill @pgmap->ref * * Notes: * 1/ At a minimum the res, ref and type members of @pgmap must be initialized @@ -159,17 +156,15 @@ static void devm_memremap_pages_release(void *data) * 2/ The altmap field may optionally be initialized, in which case altmap_valid * must be set to true * - * 3/ pgmap.ref must be 'live' on entry and 'dead' before devm_memunmap_pages() - * time (or devm release event). The expected order of events is that ref has - * been through percpu_ref_kill() before devm_memremap_pages_release(). The - * wait for the completion of all references being dropped and - * percpu_ref_exit() must occur after devm_memremap_pages_release(). + * 3/ pgmap->ref must be 'live' on entry and will be killed at + * devm_memremap_pages_release() time, or if this routine fails. * * 4/ res is expected to be a host memory range that could feasibly be * treated as a "System RAM" range, i.e. not a device mmio range, but * this is not enforced. */ -void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) +void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap, + void (*kill)(struct percpu_ref *)) { resource_size_t align_start, align_size, align_end; struct vmem_altmap *altmap = pgmap->altmap_valid ? @@ -180,6 +175,9 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) int error, nid, is_ram; struct dev_pagemap *conflict_pgmap; + if (!pgmap->ref || !kill) + return ERR_PTR(-EINVAL); + align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; @@ -205,12 +203,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) if (is_ram != REGION_DISJOINT) { WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__, is_ram == REGION_MIXED ? "mixed" : "ram", res); - return ERR_PTR(-ENXIO); + error = -ENXIO; + goto err_init; } - if (!pgmap->ref) - return ERR_PTR(-EINVAL); - pgmap->dev = dev; mutex_lock(&pgmap_lock); @@ -267,7 +263,11 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) percpu_ref_get(pgmap->ref); } - devm_add_action(dev, devm_memremap_pages_release, pgmap); + pgmap->kill = kill; + error = devm_add_action_or_reset(dev, devm_memremap_pages_release, + pgmap); + if (error) + return ERR_PTR(error); return __va(res->start); @@ -278,6 +278,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) err_pfn_remap: err_radix: pgmap_radix_release(res, pgoff); + err_init: + kill(pgmap->ref); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(devm_memremap_pages); diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c index ff9d3a5825e1..ad544e6476a9 100644 --- a/tools/testing/nvdimm/test/iomap.c +++ b/tools/testing/nvdimm/test/iomap.c @@ -104,14 +104,29 @@ void *__wrap_devm_memremap(struct device *dev, resource_size_t offset, } EXPORT_SYMBOL(__wrap_devm_memremap); -void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) +static void nfit_test_kill(void *_pgmap) +{ + struct dev_pagemap *pgmap = _pgmap; + + pgmap->kill(pgmap->ref); +} + +void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap, + void (*kill)(struct percpu_ref *)) { resource_size_t offset = pgmap->res.start; struct nfit_test_resource *nfit_res = get_nfit_res(offset); - if (nfit_res) + if (nfit_res) { + int rc; + + pgmap->kill = kill; + rc = devm_add_action_or_reset(dev, nfit_test_kill, pgmap); + if (rc) + return ERR_PTR(rc); return nfit_res->buf + offset - nfit_res->res.start; - return devm_memremap_pages(dev, pgmap); + } + return devm_memremap_pages(dev, pgmap, kill); } EXPORT_SYMBOL(__wrap_devm_memremap_pages);