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[192.55.52.151]) by mx.google.com with ESMTPS id 144si11128746pgh.524.2019.05.07.17.09.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 May 2019 17:09:47 -0700 (PDT) Received-SPF: pass (google.com: domain of dan.j.williams@intel.com designates 192.55.52.151 as permitted sender) client-ip=192.55.52.151; Authentication-Results: mx.google.com; spf=pass (google.com: domain of dan.j.williams@intel.com designates 192.55.52.151 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 fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 May 2019 17:09:46 -0700 X-ExtLoop1: 1 Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by fmsmga004.fm.intel.com with ESMTP; 07 May 2019 17:09:46 -0700 Subject: [PATCH v2 0/6] mm/devm_memremap_pages: Fix page release race From: Dan Williams To: akpm@linux-foundation.org Cc: Ira Weiny , Bjorn Helgaas , Logan Gunthorpe , Christoph Hellwig , =?utf-8?b?SsOpcsO0bWU=?= Glisse , Greg Kroah-Hartman , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-mm@kvack.org Date: Tue, 07 May 2019 16:55:59 -0700 Message-ID: <155727335978.292046.12068191395005445711.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 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: Changes since v1 [1]: - Fix a NULL-pointer deref crash in pci_p2pdma_release() (Logan) - Refresh the p2pdma patch headers to match the format of other p2pdma patches (Bjorn) - Collect Ira's reviewed-by [1]: https://lore.kernel.org/lkml/155387324370.2443841.574715745262628837.stgit@dwillia2-desk3.amr.corp.intel.com/ --- Logan audited the devm_memremap_pages() shutdown path and noticed that it was possible to proceed to arch_remove_memory() before all potential page references have been reaped. Introduce a new ->cleanup() callback to do the work of waiting for any straggling page references and then perform the percpu_ref_exit() in devm_memremap_pages_release() context. For p2pdma this involves some deeper reworks to reference count resources on a per-instance basis rather than a per pci-device basis. A modified genalloc api is introduced to convey a driver-private pointer through gen_pool_{alloc,free}() interfaces. Also, a devm_memunmap_pages() api is introduced since p2pdma does not auto-release resources on a setup failure. The dax and pmem changes pass the nvdimm unit tests, and the p2pdma changes should now pass testing with the pci_p2pdma_release() fix. Jérôme, how does this look for HMM? In general, I think these patches / fixes are suitable for v5.2-rc1 or v5.2-rc2, and since they touch kernel/memremap.c, and other various pieces of the core, they should go through the -mm tree. These patches merge cleanly with the current state of -next, pass the nvdimm unit tests, and are exposed to the 0day robot with no issues reported (https://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm.git/log/?h=libnvdimm-pending). --- Dan Williams (6): drivers/base/devres: Introduce devm_release_action() mm/devm_memremap_pages: Introduce devm_memunmap_pages PCI/P2PDMA: Fix the gen_pool_add_virt() failure path lib/genalloc: Introduce chunk owners PCI/P2PDMA: Track pgmap references per resource, not globally mm/devm_memremap_pages: Fix final page put race drivers/base/devres.c | 24 +++++++- drivers/dax/device.c | 13 +--- drivers/nvdimm/pmem.c | 17 ++++- drivers/pci/p2pdma.c | 115 +++++++++++++++++++++++-------------- include/linux/device.h | 1 include/linux/genalloc.h | 55 ++++++++++++++++-- include/linux/memremap.h | 8 +++ kernel/memremap.c | 23 ++++++- lib/genalloc.c | 51 ++++++++-------- mm/hmm.c | 14 +---- tools/testing/nvdimm/test/iomap.c | 2 + 11 files changed, 217 insertions(+), 106 deletions(-)