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author | Dan Williams <dan.j.williams@intel.com> | 2019-06-13 15:56:33 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-06-13 17:34:56 -1000 |
commit | 50f44ee7248ad2f7984ef081974a6ecd09724b3e (patch) | |
tree | ab753d9044434c94c8e6d70ead68173c2af339f6 /include/linux/memremap.h | |
parent | 1570175abd164b32ea1cc677f9dfd2dc6bd093f5 (diff) | |
download | linux-50f44ee7248ad2f7984ef081974a6ecd09724b3e.tar.gz linux-50f44ee7248ad2f7984ef081974a6ecd09724b3e.tar.bz2 linux-50f44ee7248ad2f7984ef081974a6ecd09724b3e.zip |
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: 41e94a851304 ("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>
Diffstat (limited to 'include/linux/memremap.h')
-rw-r--r-- | include/linux/memremap.h | 2 |
1 files changed, 2 insertions, 0 deletions
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; |