mm/devm_memremap_pages: fix final page put race
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.
Link: http://lkml.kernel.org/r/155727339156.292046.5432007428235387859.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 41e94a8513
("add devm_memremap_pages")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
1570175abd
commit
50f44ee724
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@ -27,9 +27,8 @@ static void dev_dax_percpu_release(struct percpu_ref *ref)
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complete(&dev_dax->cmp);
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}
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static void dev_dax_percpu_exit(void *data)
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static void dev_dax_percpu_exit(struct percpu_ref *ref)
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{
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struct percpu_ref *ref = data;
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struct dev_dax *dev_dax = ref_to_dev_dax(ref);
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dev_dbg(&dev_dax->dev, "%s\n", __func__);
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@ -466,18 +465,12 @@ int dev_dax_probe(struct device *dev)
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if (rc)
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return rc;
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rc = devm_add_action_or_reset(dev, dev_dax_percpu_exit, &dev_dax->ref);
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if (rc)
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return rc;
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dev_dax->pgmap.ref = &dev_dax->ref;
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dev_dax->pgmap.kill = dev_dax_percpu_kill;
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dev_dax->pgmap.cleanup = dev_dax_percpu_exit;
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addr = devm_memremap_pages(dev, &dev_dax->pgmap);
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if (IS_ERR(addr)) {
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devm_remove_action(dev, dev_dax_percpu_exit, &dev_dax->ref);
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percpu_ref_exit(&dev_dax->ref);
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if (IS_ERR(addr))
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return PTR_ERR(addr);
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}
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inode = dax_inode(dax_dev);
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cdev = inode->i_cdev;
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@ -303,11 +303,19 @@ static const struct attribute_group *pmem_attribute_groups[] = {
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NULL,
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};
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static void pmem_release_queue(void *q)
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static void __pmem_release_queue(struct percpu_ref *ref)
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{
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struct request_queue *q;
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q = container_of(ref, typeof(*q), q_usage_counter);
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blk_cleanup_queue(q);
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}
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static void pmem_release_queue(void *ref)
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{
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__pmem_release_queue(ref);
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}
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static void pmem_freeze_queue(struct percpu_ref *ref)
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{
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struct request_queue *q;
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@ -399,12 +407,10 @@ static int pmem_attach_disk(struct device *dev,
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if (!q)
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return -ENOMEM;
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if (devm_add_action_or_reset(dev, pmem_release_queue, q))
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return -ENOMEM;
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pmem->pfn_flags = PFN_DEV;
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pmem->pgmap.ref = &q->q_usage_counter;
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pmem->pgmap.kill = pmem_freeze_queue;
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pmem->pgmap.cleanup = __pmem_release_queue;
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if (is_nd_pfn(dev)) {
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if (setup_pagemap_fsdax(dev, &pmem->pgmap))
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return -ENOMEM;
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@ -425,6 +431,9 @@ static int pmem_attach_disk(struct device *dev,
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pmem->pfn_flags |= PFN_MAP;
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memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
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} else {
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if (devm_add_action_or_reset(dev, pmem_release_queue,
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&q->q_usage_counter))
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return -ENOMEM;
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addr = devm_memremap(dev, pmem->phys_addr,
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pmem->size, ARCH_MEMREMAP_PMEM);
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memcpy(&bb_res, &nsio->res, sizeof(bb_res));
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@ -95,7 +95,7 @@ static void pci_p2pdma_percpu_kill(struct percpu_ref *ref)
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percpu_ref_kill(ref);
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}
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static void pci_p2pdma_percpu_cleanup(void *ref)
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static void pci_p2pdma_percpu_cleanup(struct percpu_ref *ref)
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{
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struct p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(ref);
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@ -198,16 +198,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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if (error)
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goto pgmap_free;
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/*
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* FIXME: the percpu_ref_exit needs to be coordinated internal
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* to devm_memremap_pages_release(). Duplicate the same ordering
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* as other devm_memremap_pages() users for now.
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*/
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error = devm_add_action(&pdev->dev, pci_p2pdma_percpu_cleanup,
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&p2p_pgmap->ref);
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if (error)
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goto ref_cleanup;
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pgmap = &p2p_pgmap->pgmap;
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pgmap->res.start = pci_resource_start(pdev, bar) + offset;
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@ -218,11 +208,12 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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pgmap->pci_p2pdma_bus_offset = pci_bus_address(pdev, bar) -
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pci_resource_start(pdev, bar);
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pgmap->kill = pci_p2pdma_percpu_kill;
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pgmap->cleanup = pci_p2pdma_percpu_cleanup;
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addr = devm_memremap_pages(&pdev->dev, pgmap);
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if (IS_ERR(addr)) {
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error = PTR_ERR(addr);
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goto ref_exit;
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goto pgmap_free;
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}
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error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr,
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@ -239,8 +230,6 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
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pages_free:
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devm_memunmap_pages(&pdev->dev, pgmap);
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ref_cleanup:
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percpu_ref_exit(&p2p_pgmap->ref);
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pgmap_free:
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devm_kfree(&pdev->dev, p2p_pgmap);
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return error;
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@ -81,6 +81,7 @@ typedef void (*dev_page_free_t)(struct page *page, void *data);
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* @res: physical address range covered by @ref
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* @ref: reference count that pins the devm_memremap_pages() mapping
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* @kill: callback to transition @ref to the dead state
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* @cleanup: callback to wait for @ref to be idle and reap it
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* @dev: host device of the mapping for debug
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* @data: private data pointer for page_free()
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* @type: memory type: see MEMORY_* in memory_hotplug.h
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@ -92,6 +93,7 @@ struct dev_pagemap {
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struct resource res;
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struct percpu_ref *ref;
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void (*kill)(struct percpu_ref *ref);
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void (*cleanup)(struct percpu_ref *ref);
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struct device *dev;
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void *data;
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enum memory_type type;
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@ -95,6 +95,7 @@ static void devm_memremap_pages_release(void *data)
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pgmap->kill(pgmap->ref);
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for_each_device_pfn(pfn, pgmap)
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put_page(pfn_to_page(pfn));
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pgmap->cleanup(pgmap->ref);
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/* pages are dead and unused, undo the arch mapping */
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align_start = res->start & ~(SECTION_SIZE - 1);
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@ -133,8 +134,8 @@ static void devm_memremap_pages_release(void *data)
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* 2/ The altmap field may optionally be initialized, in which case altmap_valid
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* must be set to true
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*
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* 3/ pgmap->ref must be 'live' on entry and will be killed at
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* devm_memremap_pages_release() time, or if this routine fails.
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* 3/ pgmap->ref must be 'live' on entry and will be killed and reaped
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* at devm_memremap_pages_release() time, or if this routine fails.
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*
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* 4/ res is expected to be a host memory range that could feasibly be
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* treated as a "System RAM" range, i.e. not a device mmio range, but
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@ -156,8 +157,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
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pgprot_t pgprot = PAGE_KERNEL;
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int error, nid, is_ram;
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if (!pgmap->ref || !pgmap->kill)
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if (!pgmap->ref || !pgmap->kill || !pgmap->cleanup) {
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WARN(1, "Missing reference count teardown definition\n");
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return ERR_PTR(-EINVAL);
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}
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align_start = res->start & ~(SECTION_SIZE - 1);
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align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE)
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if (conflict_pgmap) {
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dev_WARN(dev, "Conflicting mapping in same section\n");
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put_dev_pagemap(conflict_pgmap);
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return ERR_PTR(-ENOMEM);
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error = -ENOMEM;
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goto err_array;
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}
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conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL);
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if (conflict_pgmap) {
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dev_WARN(dev, "Conflicting mapping in same section\n");
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put_dev_pagemap(conflict_pgmap);
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return ERR_PTR(-ENOMEM);
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error = -ENOMEM;
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goto err_array;
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}
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is_ram = region_intersects(align_start, align_size,
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pgmap_array_delete(res);
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err_array:
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pgmap->kill(pgmap->ref);
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pgmap->cleanup(pgmap->ref);
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return ERR_PTR(error);
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}
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EXPORT_SYMBOL_GPL(devm_memremap_pages);
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14
mm/hmm.c
14
mm/hmm.c
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@ -1354,9 +1354,8 @@ static void hmm_devmem_ref_release(struct percpu_ref *ref)
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complete(&devmem->completion);
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}
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static void hmm_devmem_ref_exit(void *data)
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static void hmm_devmem_ref_exit(struct percpu_ref *ref)
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{
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struct percpu_ref *ref = data;
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struct hmm_devmem *devmem;
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devmem = container_of(ref, struct hmm_devmem, ref);
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if (ret)
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return ERR_PTR(ret);
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ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, &devmem->ref);
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if (ret)
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return ERR_PTR(ret);
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size = ALIGN(size, PA_SECTION_SIZE);
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addr = min((unsigned long)iomem_resource.end,
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(1UL << MAX_PHYSMEM_BITS) - 1);
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@ -1475,6 +1470,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
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devmem->pagemap.ref = &devmem->ref;
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devmem->pagemap.data = devmem;
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devmem->pagemap.kill = hmm_devmem_ref_kill;
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devmem->pagemap.cleanup = hmm_devmem_ref_exit;
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result = devm_memremap_pages(devmem->device, &devmem->pagemap);
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if (IS_ERR(result))
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@ -1512,11 +1508,6 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
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if (ret)
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return ERR_PTR(ret);
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ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit,
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&devmem->ref);
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if (ret)
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return ERR_PTR(ret);
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devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
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devmem->pfn_last = devmem->pfn_first +
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(resource_size(devmem->resource) >> PAGE_SHIFT);
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@ -1529,6 +1520,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
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devmem->pagemap.ref = &devmem->ref;
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devmem->pagemap.data = devmem;
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devmem->pagemap.kill = hmm_devmem_ref_kill;
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devmem->pagemap.cleanup = hmm_devmem_ref_exit;
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result = devm_memremap_pages(devmem->device, &devmem->pagemap);
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if (IS_ERR(result))
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@ -100,7 +100,9 @@ static void nfit_test_kill(void *_pgmap)
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{
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struct dev_pagemap *pgmap = _pgmap;
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WARN_ON(!pgmap || !pgmap->ref || !pgmap->kill || !pgmap->cleanup);
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pgmap->kill(pgmap->ref);
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pgmap->cleanup(pgmap->ref);
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}
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void *__wrap_devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
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