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authorDan Williams <dan.j.williams@intel.com>2019-06-13 15:56:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-06-13 17:34:56 -1000
commit50f44ee7248ad2f7984ef081974a6ecd09724b3e (patch)
treeab753d9044434c94c8e6d70ead68173c2af339f6 /tools
parent1570175abd164b32ea1cc677f9dfd2dc6bd093f5 (diff)
downloadlinux-50f44ee7248ad2f7984ef081974a6ecd09724b3e.tar.bz2
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')
-rw-r--r--tools/testing/nvdimm/test/iomap.c2
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)