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[192.55.52.115]) by mx.google.com with ESMTPS id t2-v6si1566256pge.64.2018.09.24.23.27.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Sep 2018 23:27:30 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 192.55.52.115 as permitted sender) client-ip=192.55.52.115; Authentication-Results: mx.google.com; spf=pass (google.com: domain of dan.j.williams@intel.com designates 192.55.52.115 as permitted sender) smtp.mailfrom=dan.j.williams@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Sep 2018 23:27:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,301,1534834800"; d="scan'208";a="92990656" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by fmsmga001.fm.intel.com with ESMTP; 24 Sep 2018 23:26:57 -0700 Subject: [PATCH v6 3/7] mm, devm_memremap_pages: Fix shutdown handling From: Dan Williams To: akpm@linux-foundation.org Cc: stable@vger.kernel.org, =?utf-8?b?SsOpcsO0bWU=?= Glisse , Logan Gunthorpe , Logan Gunthorpe , Christoph Hellwig , alexander.h.duyck@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Mon, 24 Sep 2018 23:15:10 -0700 Message-ID: <153785611023.283091.14768029396517384268.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <153785609460.283091.17422092801700439095.stgit@dwillia2-desk3.amr.corp.intel.com> References: <153785609460.283091.17422092801700439095.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-2-gc94f MIME-Version: 1.0 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: X-Virus-Scanned: ClamAV using ClamSMTP 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...") Reviewed-by: "Jérôme Glisse" Reported-by: Logan Gunthorpe Reviewed-by: Logan Gunthorpe Reviewed-by: Christoph Hellwig Signed-off-by: Dan Williams --- drivers/dax/pmem.c | 14 +++----------- drivers/nvdimm/pmem.c | 13 +++++-------- include/linux/memremap.h | 2 ++ kernel/memremap.c | 31 +++++++++++++++---------------- tools/testing/nvdimm/test/iomap.c | 15 ++++++++++++++- 5 files changed, 39 insertions(+), 36 deletions(-) diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c index 99e2aace8078..2c1f459c0c63 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 +111,10 @@ static int dax_pmem_probe(struct device *dev) } dax_pmem->pgmap.ref = &dax_pmem->ref; + dax_pmem->pgmap.kill = dax_pmem_percpu_kill; 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); + 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..52f72ad8fe1e 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); } @@ -402,6 +405,7 @@ static int pmem_attach_disk(struct device *dev, pmem->pfn_flags = PFN_DEV; pmem->pgmap.ref = &q->q_usage_counter; + pmem->pgmap.kill = pmem_freeze_queue; if (is_nd_pfn(dev)) { if (setup_pagemap_fsdax(dev, &pmem->pgmap)) return -ENOMEM; @@ -425,13 +429,6 @@ static int pmem_attach_disk(struct device *dev, 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..a84572cdc438 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 @@ -117,6 +118,7 @@ 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; diff --git a/kernel/memremap.c b/kernel/memremap.c index 92e838127767..fe2a9cd0b9c1 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 +146,7 @@ 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 * * Notes: * 1/ At a minimum the res, ref and type members of @pgmap must be initialized @@ -159,11 +155,8 @@ 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 @@ -180,6 +173,9 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) int error, nid, is_ram; struct dev_pagemap *conflict_pgmap; + if (!pgmap->ref || !pgmap->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 +201,10 @@ 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 +261,10 @@ 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); + error = devm_add_action_or_reset(dev, devm_memremap_pages_release, + pgmap); + if (error) + return ERR_PTR(error); return __va(res->start); @@ -278,6 +275,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) err_pfn_remap: err_radix: pgmap_radix_release(res, pgoff); + err_init: + pgmap->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 ed18a0cbc0c8..c6635fee27d8 100644 --- a/tools/testing/nvdimm/test/iomap.c +++ b/tools/testing/nvdimm/test/iomap.c @@ -104,13 +104,26 @@ void *__wrap_devm_memremap(struct device *dev, resource_size_t offset, } EXPORT_SYMBOL(__wrap_devm_memremap); +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) { 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; + + 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); } EXPORT_SYMBOL_GPL(__wrap_devm_memremap_pages);