diff options
| author | Dan Williams | 2019-06-13 15:56:33 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2019-06-13 17:34:56 -1000 |
| commit | 50f44ee7248ad2f7984ef081974a6ecd09724b3e (patch) | |
| tree | ab753d9044434c94c8e6d70ead68173c2af339f6 /drivers/nvdimm | |
| parent | 1570175abd164b32ea1cc677f9dfd2dc6bd093f5 (diff) | |
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 'drivers/nvdimm')
| -rw-r--r-- | drivers/nvdimm/pmem.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 28cb44c61d4a..24d7fe7c74ed 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -303,11 +303,19 @@ 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; @@ -399,12 +407,10 @@ 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; @@ -425,6 +431,9 @@ 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)); |