| Message ID | 155387327591.2443841.1024616899609926902.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/devm_memremap_pages: Fix page release race | expand |
On Fri, Mar 29, 2019 at 08:27:55AM -0700, Dan Williams wrote: > Logan noticed that devm_memremap_pages_release() kills the percpu_ref > drops all the page references that were acquired at init and then > immediately proceeds to unplug, arch_remove_memory(), the backing pages > for the pagemap. If for some reason device shutdown actually collides > with a busy / elevated-ref-count page then arch_remove_memory() should > be deferred until after that reference is dropped. > > As it stands the "wait for last page ref drop" happens *after* > devm_memremap_pages_release() returns, which is obviously too late and > can lead to crashes. > > Fix this situation by assigning the responsibility to wait for the > percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup() > callback. Implement the new cleanup callback for all > devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma. > > Reported-by: Logan Gunthorpe <logang@deltatee.com> > Fixes: 41e94a851304 ("add devm_memremap_pages") > Cc: Ira Weiny <ira.weiny@intel.com> > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: Christoph Hellwig <hch@lst.de> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> For the series: Reviewed-by: Ira Weiny <ira.weiny@intel.com> > --- > drivers/dax/device.c | 13 +++---------- > drivers/nvdimm/pmem.c | 17 +++++++++++++---- > drivers/pci/p2pdma.c | 17 +++-------------- > include/linux/memremap.h | 2 ++ > kernel/memremap.c | 17 ++++++++++++----- > mm/hmm.c | 14 +++----------- > tools/testing/nvdimm/test/iomap.c | 2 ++ > 7 files changed, 38 insertions(+), 44 deletions(-) > > diff --git a/drivers/dax/device.c b/drivers/dax/device.c > index e428468ab661..e3aa78dd1bb0 100644 > --- a/drivers/dax/device.c > +++ b/drivers/dax/device.c > @@ -27,9 +27,8 @@ static void dev_dax_percpu_release(struct percpu_ref *ref) > complete(&dev_dax->cmp); > } > > -static void dev_dax_percpu_exit(void *data) > +static void dev_dax_percpu_exit(struct percpu_ref *ref) > { > - struct percpu_ref *ref = data; > struct dev_dax *dev_dax = ref_to_dev_dax(ref); > > dev_dbg(&dev_dax->dev, "%s\n", __func__); > @@ -468,18 +467,12 @@ int dev_dax_probe(struct device *dev) > if (rc) > return rc; > > - rc = devm_add_action_or_reset(dev, dev_dax_percpu_exit, &dev_dax->ref); > - if (rc) > - return rc; > - > dev_dax->pgmap.ref = &dev_dax->ref; > dev_dax->pgmap.kill = dev_dax_percpu_kill; > + dev_dax->pgmap.cleanup = dev_dax_percpu_exit; > addr = devm_memremap_pages(dev, &dev_dax->pgmap); > - if (IS_ERR(addr)) { > - devm_remove_action(dev, dev_dax_percpu_exit, &dev_dax->ref); > - percpu_ref_exit(&dev_dax->ref); > + if (IS_ERR(addr)) > return PTR_ERR(addr); > - } > > inode = dax_inode(dax_dev); > cdev = inode->i_cdev; > diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c > index bc2f700feef8..507b9eda42aa 100644 > --- a/drivers/nvdimm/pmem.c > +++ b/drivers/nvdimm/pmem.c > @@ -304,11 +304,19 @@ static const struct attribute_group *pmem_attribute_groups[] = { > NULL, > }; > > -static void pmem_release_queue(void *q) > +static void __pmem_release_queue(struct percpu_ref *ref) > { > + struct request_queue *q; > + > + q = container_of(ref, typeof(*q), q_usage_counter); > blk_cleanup_queue(q); > } > > +static void pmem_release_queue(void *ref) > +{ > + __pmem_release_queue(ref); > +} > + > static void pmem_freeze_queue(struct percpu_ref *ref) > { > struct request_queue *q; > @@ -400,12 +408,10 @@ static int pmem_attach_disk(struct device *dev, > if (!q) > return -ENOMEM; > > - if (devm_add_action_or_reset(dev, pmem_release_queue, q)) > - return -ENOMEM; > - > pmem->pfn_flags = PFN_DEV; > pmem->pgmap.ref = &q->q_usage_counter; > pmem->pgmap.kill = pmem_freeze_queue; > + pmem->pgmap.cleanup = __pmem_release_queue; > if (is_nd_pfn(dev)) { > if (setup_pagemap_fsdax(dev, &pmem->pgmap)) > return -ENOMEM; > @@ -426,6 +432,9 @@ static int pmem_attach_disk(struct device *dev, > pmem->pfn_flags |= PFN_MAP; > memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res)); > } else { > + if (devm_add_action_or_reset(dev, pmem_release_queue, > + &q->q_usage_counter)) > + return -ENOMEM; > addr = devm_memremap(dev, pmem->phys_addr, > pmem->size, ARCH_MEMREMAP_PMEM); > memcpy(&bb_res, &nsio->res, sizeof(bb_res)); > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c > index 1b96c1688715..7ff5b8067670 100644 > --- a/drivers/pci/p2pdma.c > +++ b/drivers/pci/p2pdma.c > @@ -95,7 +95,7 @@ static void pci_p2pdma_percpu_kill(struct percpu_ref *ref) > percpu_ref_kill(ref); > } > > -static void pci_p2pdma_percpu_cleanup(void *ref) > +static void pci_p2pdma_percpu_cleanup(struct percpu_ref *ref) > { > struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref); > > @@ -197,16 +197,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, > if (error) > goto pgmap_free; > > - /* > - * FIXME: the percpu_ref_exit needs to be coordinated internal > - * to devm_memremap_pages_release(). Duplicate the same ordering > - * as other devm_memremap_pages() users for now. > - */ > - error = devm_add_action(&pdev->dev, pci_p2pdma_percpu_cleanup, > - &p2p_pgmap->ref); > - if (error) > - goto ref_cleanup; > - > pgmap = &p2p_pgmap->pgmap; > > pgmap->res.start = pci_resource_start(pdev, bar) + offset; > @@ -217,11 +207,12 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, > pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) - > pci_resource_start(pdev, bar); > pgmap->kill = pci_p2pdma_percpu_kill; > + pgmap->cleanup = pci_p2pdma_percpu_cleanup; > > addr = devm_memremap_pages(&pdev->dev, pgmap); > if (IS_ERR(addr)) { > error = PTR_ERR(addr); > - goto ref_exit; > + goto pgmap_free; > } > > error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr, > @@ -238,8 +229,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, > > pages_free: > devm_memunmap_pages(&pdev->dev, pgmap); > -ref_cleanup: > - percpu_ref_exit(&p2p_pgmap->ref); > pgmap_free: > devm_kfree(&pdev->dev, p2p_pgmap); > return error; > diff --git a/include/linux/memremap.h b/include/linux/memremap.h > index 7601ee314c4a..1732dea030b2 100644 > --- a/include/linux/memremap.h > +++ b/include/linux/memremap.h > @@ -81,6 +81,7 @@ typedef void (*dev_page_free_t)(struct page *page, void *data); > * @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 > + * @cleanup: callback to wait for @ref to be idle and reap it > * @dev: host device of the mapping for debug > * @data: private data pointer for page_free() > * @type: memory type: see MEMORY_* in memory_hotplug.h > @@ -92,6 +93,7 @@ struct dev_pagemap { > struct resource res; > struct percpu_ref *ref; > void (*kill)(struct percpu_ref *ref); > + void (*cleanup)(struct percpu_ref *ref); > struct device *dev; > void *data; > enum memory_type type; > diff --git a/kernel/memremap.c b/kernel/memremap.c > index 65afbacab44e..05d1af5a2f15 100644 > --- a/kernel/memremap.c > +++ b/kernel/memremap.c > @@ -96,6 +96,7 @@ static void devm_memremap_pages_release(void *data) > pgmap->kill(pgmap->ref); > for_each_device_pfn(pfn, pgmap) > put_page(pfn_to_page(pfn)); > + pgmap->cleanup(pgmap->ref); > > /* pages are dead and unused, undo the arch mapping */ > align_start = res->start & ~(SECTION_SIZE - 1); > @@ -134,8 +135,8 @@ 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 will be killed at > - * devm_memremap_pages_release() time, or if this routine fails. > + * 3/ pgmap->ref must be 'live' on entry and will be killed and reaped > + * 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 > @@ -151,8 +152,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > pgprot_t pgprot = PAGE_KERNEL; > int error, nid, is_ram; > > - if (!pgmap->ref || !pgmap->kill) > + if (!pgmap->ref || !pgmap->kill || !pgmap->cleanup) { > + WARN(1, "Missing reference count teardown definition\n"); > return ERR_PTR(-EINVAL); > + } > > align_start = res->start & ~(SECTION_SIZE - 1); > align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) > @@ -163,14 +166,16 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > if (conflict_pgmap) { > dev_WARN(dev, "Conflicting mapping in same section\n"); > put_dev_pagemap(conflict_pgmap); > - return ERR_PTR(-ENOMEM); > + error = -ENOMEM; > + goto err_array; > } > > conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); > if (conflict_pgmap) { > dev_WARN(dev, "Conflicting mapping in same section\n"); > put_dev_pagemap(conflict_pgmap); > - return ERR_PTR(-ENOMEM); > + error = -ENOMEM; > + goto err_array; > } > > is_ram = region_intersects(align_start, align_size, > @@ -262,6 +267,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) > pgmap_array_delete(res); > err_array: > pgmap->kill(pgmap->ref); > + pgmap->cleanup(pgmap->ref); > + > return ERR_PTR(error); > } > EXPORT_SYMBOL_GPL(devm_memremap_pages); > diff --git a/mm/hmm.c b/mm/hmm.c > index fe1cd87e49ac..225ade644058 100644 > --- a/mm/hmm.c > +++ b/mm/hmm.c > @@ -975,9 +975,8 @@ static void hmm_devmem_ref_release(struct percpu_ref *ref) > complete(&devmem->completion); > } > > -static void hmm_devmem_ref_exit(void *data) > +static void hmm_devmem_ref_exit(struct percpu_ref *ref) > { > - struct percpu_ref *ref = data; > struct hmm_devmem *devmem; > > devmem = container_of(ref, struct hmm_devmem, ref); > @@ -1054,10 +1053,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, > if (ret) > return ERR_PTR(ret); > > - ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, &devmem->ref); > - if (ret) > - return ERR_PTR(ret); > - > size = ALIGN(size, PA_SECTION_SIZE); > addr = min((unsigned long)iomem_resource.end, > (1UL << MAX_PHYSMEM_BITS) - 1); > @@ -1096,6 +1091,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, > devmem->pagemap.ref = &devmem->ref; > devmem->pagemap.data = devmem; > devmem->pagemap.kill = hmm_devmem_ref_kill; > + devmem->pagemap.cleanup = hmm_devmem_ref_exit; > > result = devm_memremap_pages(devmem->device, &devmem->pagemap); > if (IS_ERR(result)) > @@ -1133,11 +1129,6 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, > if (ret) > return ERR_PTR(ret); > > - ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, > - &devmem->ref); > - if (ret) > - return ERR_PTR(ret); > - > devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; > devmem->pfn_last = devmem->pfn_first + > (resource_size(devmem->resource) >> PAGE_SHIFT); > @@ -1150,6 +1141,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, > devmem->pagemap.ref = &devmem->ref; > devmem->pagemap.data = devmem; > devmem->pagemap.kill = hmm_devmem_ref_kill; > + devmem->pagemap.cleanup = hmm_devmem_ref_exit; > > result = devm_memremap_pages(devmem->device, &devmem->pagemap); > if (IS_ERR(result)) > diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c > index c6635fee27d8..219dd0a1cb08 100644 > --- a/tools/testing/nvdimm/test/iomap.c > +++ b/tools/testing/nvdimm/test/iomap.c > @@ -108,7 +108,9 @@ static void nfit_test_kill(void *_pgmap) > { > struct dev_pagemap *pgmap = _pgmap; > > + WARN_ON(!pgmap || !pgmap->ref || !pgmap->kill || !pgmap->cleanup); > pgmap->kill(pgmap->ref); > + pgmap->cleanup(pgmap->ref); > } > > void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) >
diff --git a/drivers/dax/device.c b/drivers/dax/device.c index e428468ab661..e3aa78dd1bb0 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -27,9 +27,8 @@ static void dev_dax_percpu_release(struct percpu_ref *ref) complete(&dev_dax->cmp); } -static void dev_dax_percpu_exit(void *data) +static void dev_dax_percpu_exit(struct percpu_ref *ref) { - struct percpu_ref *ref = data; struct dev_dax *dev_dax = ref_to_dev_dax(ref); dev_dbg(&dev_dax->dev, "%s\n", __func__); @@ -468,18 +467,12 @@ int dev_dax_probe(struct device *dev) if (rc) return rc; - rc = devm_add_action_or_reset(dev, dev_dax_percpu_exit, &dev_dax->ref); - if (rc) - return rc; - dev_dax->pgmap.ref = &dev_dax->ref; dev_dax->pgmap.kill = dev_dax_percpu_kill; + dev_dax->pgmap.cleanup = dev_dax_percpu_exit; addr = devm_memremap_pages(dev, &dev_dax->pgmap); - if (IS_ERR(addr)) { - devm_remove_action(dev, dev_dax_percpu_exit, &dev_dax->ref); - percpu_ref_exit(&dev_dax->ref); + if (IS_ERR(addr)) return PTR_ERR(addr); - } inode = dax_inode(dax_dev); cdev = inode->i_cdev; diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index bc2f700feef8..507b9eda42aa 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -304,11 +304,19 @@ static const struct attribute_group *pmem_attribute_groups[] = { NULL, }; -static void pmem_release_queue(void *q) +static void __pmem_release_queue(struct percpu_ref *ref) { + struct request_queue *q; + + q = container_of(ref, typeof(*q), q_usage_counter); blk_cleanup_queue(q); } +static void pmem_release_queue(void *ref) +{ + __pmem_release_queue(ref); +} + static void pmem_freeze_queue(struct percpu_ref *ref) { struct request_queue *q; @@ -400,12 +408,10 @@ static int pmem_attach_disk(struct device *dev, if (!q) return -ENOMEM; - if (devm_add_action_or_reset(dev, pmem_release_queue, q)) - return -ENOMEM; - pmem->pfn_flags = PFN_DEV; pmem->pgmap.ref = &q->q_usage_counter; pmem->pgmap.kill = pmem_freeze_queue; + pmem->pgmap.cleanup = __pmem_release_queue; if (is_nd_pfn(dev)) { if (setup_pagemap_fsdax(dev, &pmem->pgmap)) return -ENOMEM; @@ -426,6 +432,9 @@ static int pmem_attach_disk(struct device *dev, pmem->pfn_flags |= PFN_MAP; memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res)); } else { + if (devm_add_action_or_reset(dev, pmem_release_queue, + &q->q_usage_counter)) + return -ENOMEM; addr = devm_memremap(dev, pmem->phys_addr, pmem->size, ARCH_MEMREMAP_PMEM); memcpy(&bb_res, &nsio->res, sizeof(bb_res)); diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 1b96c1688715..7ff5b8067670 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -95,7 +95,7 @@ static void pci_p2pdma_percpu_kill(struct percpu_ref *ref) percpu_ref_kill(ref); } -static void pci_p2pdma_percpu_cleanup(void *ref) +static void pci_p2pdma_percpu_cleanup(struct percpu_ref *ref) { struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref); @@ -197,16 +197,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, if (error) goto pgmap_free; - /* - * FIXME: the percpu_ref_exit needs to be coordinated internal - * to devm_memremap_pages_release(). Duplicate the same ordering - * as other devm_memremap_pages() users for now. - */ - error = devm_add_action(&pdev->dev, pci_p2pdma_percpu_cleanup, - &p2p_pgmap->ref); - if (error) - goto ref_cleanup; - pgmap = &p2p_pgmap->pgmap; pgmap->res.start = pci_resource_start(pdev, bar) + offset; @@ -217,11 +207,12 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) - pci_resource_start(pdev, bar); pgmap->kill = pci_p2pdma_percpu_kill; + pgmap->cleanup = pci_p2pdma_percpu_cleanup; addr = devm_memremap_pages(&pdev->dev, pgmap); if (IS_ERR(addr)) { error = PTR_ERR(addr); - goto ref_exit; + goto pgmap_free; } error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr, @@ -238,8 +229,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, pages_free: devm_memunmap_pages(&pdev->dev, pgmap); -ref_cleanup: - percpu_ref_exit(&p2p_pgmap->ref); pgmap_free: devm_kfree(&pdev->dev, p2p_pgmap); return error; diff --git a/include/linux/memremap.h b/include/linux/memremap.h index 7601ee314c4a..1732dea030b2 100644 --- a/include/linux/memremap.h +++ b/include/linux/memremap.h @@ -81,6 +81,7 @@ typedef void (*dev_page_free_t)(struct page *page, void *data); * @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 + * @cleanup: callback to wait for @ref to be idle and reap it * @dev: host device of the mapping for debug * @data: private data pointer for page_free() * @type: memory type: see MEMORY_* in memory_hotplug.h @@ -92,6 +93,7 @@ struct dev_pagemap { struct resource res; struct percpu_ref *ref; void (*kill)(struct percpu_ref *ref); + void (*cleanup)(struct percpu_ref *ref); struct device *dev; void *data; enum memory_type type; diff --git a/kernel/memremap.c b/kernel/memremap.c index 65afbacab44e..05d1af5a2f15 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -96,6 +96,7 @@ static void devm_memremap_pages_release(void *data) pgmap->kill(pgmap->ref); for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); + pgmap->cleanup(pgmap->ref); /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); @@ -134,8 +135,8 @@ 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 will be killed at - * devm_memremap_pages_release() time, or if this routine fails. + * 3/ pgmap->ref must be 'live' on entry and will be killed and reaped + * 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 @@ -151,8 +152,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) pgprot_t pgprot = PAGE_KERNEL; int error, nid, is_ram; - if (!pgmap->ref || !pgmap->kill) + if (!pgmap->ref || !pgmap->kill || !pgmap->cleanup) { + WARN(1, "Missing reference count teardown definition\n"); return ERR_PTR(-EINVAL); + } align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) @@ -163,14 +166,16 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) if (conflict_pgmap) { dev_WARN(dev, "Conflicting mapping in same section\n"); put_dev_pagemap(conflict_pgmap); - return ERR_PTR(-ENOMEM); + error = -ENOMEM; + goto err_array; } conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); if (conflict_pgmap) { dev_WARN(dev, "Conflicting mapping in same section\n"); put_dev_pagemap(conflict_pgmap); - return ERR_PTR(-ENOMEM); + error = -ENOMEM; + goto err_array; } is_ram = region_intersects(align_start, align_size, @@ -262,6 +267,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) pgmap_array_delete(res); err_array: pgmap->kill(pgmap->ref); + pgmap->cleanup(pgmap->ref); + return ERR_PTR(error); } EXPORT_SYMBOL_GPL(devm_memremap_pages); diff --git a/mm/hmm.c b/mm/hmm.c index fe1cd87e49ac..225ade644058 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -975,9 +975,8 @@ static void hmm_devmem_ref_release(struct percpu_ref *ref) complete(&devmem->completion); } -static void hmm_devmem_ref_exit(void *data) +static void hmm_devmem_ref_exit(struct percpu_ref *ref) { - struct percpu_ref *ref = data; struct hmm_devmem *devmem; devmem = container_of(ref, struct hmm_devmem, ref); @@ -1054,10 +1053,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, if (ret) return ERR_PTR(ret); - ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, &devmem->ref); - if (ret) - return ERR_PTR(ret); - size = ALIGN(size, PA_SECTION_SIZE); addr = min((unsigned long)iomem_resource.end, (1UL << MAX_PHYSMEM_BITS) - 1); @@ -1096,6 +1091,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, devmem->pagemap.ref = &devmem->ref; devmem->pagemap.data = devmem; devmem->pagemap.kill = hmm_devmem_ref_kill; + devmem->pagemap.cleanup = hmm_devmem_ref_exit; result = devm_memremap_pages(devmem->device, &devmem->pagemap); if (IS_ERR(result)) @@ -1133,11 +1129,6 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, if (ret) return ERR_PTR(ret); - ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, - &devmem->ref); - if (ret) - return ERR_PTR(ret); - devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT; devmem->pfn_last = devmem->pfn_first + (resource_size(devmem->resource) >> PAGE_SHIFT); @@ -1150,6 +1141,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops, devmem->pagemap.ref = &devmem->ref; devmem->pagemap.data = devmem; devmem->pagemap.kill = hmm_devmem_ref_kill; + devmem->pagemap.cleanup = hmm_devmem_ref_exit; result = devm_memremap_pages(devmem->device, &devmem->pagemap); if (IS_ERR(result)) diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c index c6635fee27d8..219dd0a1cb08 100644 --- a/tools/testing/nvdimm/test/iomap.c +++ b/tools/testing/nvdimm/test/iomap.c @@ -108,7 +108,9 @@ static void nfit_test_kill(void *_pgmap) { struct dev_pagemap *pgmap = _pgmap; + WARN_ON(!pgmap || !pgmap->ref || !pgmap->kill || !pgmap->cleanup); pgmap->kill(pgmap->ref); + pgmap->cleanup(pgmap->ref); } void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
Logan noticed that devm_memremap_pages_release() kills the percpu_ref drops all the page references that were acquired at init and then immediately proceeds to unplug, arch_remove_memory(), the backing pages for the pagemap. If for some reason device shutdown actually collides with a busy / elevated-ref-count page then arch_remove_memory() should be deferred until after that reference is dropped. As it stands the "wait for last page ref drop" happens *after* devm_memremap_pages_release() returns, which is obviously too late and can lead to crashes. Fix this situation by assigning the responsibility to wait for the percpu_ref to go idle to devm_memremap_pages() with a new ->cleanup() callback. Implement the new cleanup callback for all devm_memremap_pages() users: pmem, devdax, hmm, and p2pdma. Reported-by: Logan Gunthorpe <logang@deltatee.com> Fixes: 41e94a851304 ("add devm_memremap_pages") Cc: Ira Weiny <ira.weiny@intel.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- drivers/dax/device.c | 13 +++---------- drivers/nvdimm/pmem.c | 17 +++++++++++++---- drivers/pci/p2pdma.c | 17 +++-------------- include/linux/memremap.h | 2 ++ kernel/memremap.c | 17 ++++++++++++----- mm/hmm.c | 14 +++----------- tools/testing/nvdimm/test/iomap.c | 2 ++ 7 files changed, 38 insertions(+), 44 deletions(-)