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| author | Dan Williams <dan.j.williams@intel.com> | 2019-06-13 15:56:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-06-13 17:34:56 -1000 |
| commit | 50f44ee7248ad2f7984ef081974a6ecd09724b3e (patch) | |
| tree | ab753d9044434c94c8e6d70ead68173c2af339f6 /tools/testing/nvdimm | |
| parent | 1570175abd164b32ea1cc677f9dfd2dc6bd093f5 (diff) | |
| download | lwn-50f44ee7248ad2f7984ef081974a6ecd09724b3e.tar.gz lwn-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 'tools/testing/nvdimm')
| -rw-r--r-- | tools/testing/nvdimm/test/iomap.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/tools/testing/nvdimm/test/iomap.c b/tools/testing/nvdimm/test/iomap.c index 280015c22598..076df22e4bda 100644 --- a/tools/testing/nvdimm/test/iomap.c +++ b/tools/testing/nvdimm/test/iomap.c @@ -100,7 +100,9 @@ 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) |