The patch titled
Subject: mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}
has been added to the -mm tree. Its filename is
mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_begin-done.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_begin-done.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_begin-done.patch
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------------------------------------------------------
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}
The mem_hotplug_{begin,done} lock coordinates with {get,put}_online_mems()
to hold off "readers" of the current state of memory from new hotplug
actions. mem_hotplug_begin() expects exclusive access, via the
device_hotplug lock, to set mem_hotplug.active_writer. Calling
mem_hotplug_begin() without locking device_hotplug can lead to corrupting
mem_hotplug.refcount and missed wakeups / soft lockups.
Link: http://lkml.kernel.org/r/148693885680.16345.17802627926777862337.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: f931ab479dd2 ("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}")
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/memremap.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN kernel/memremap.c~mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_begin-done kernel/memremap.c
--- a/kernel/memremap.c~mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_begin-done
+++ a/kernel/memremap.c
@@ -264,9 +264,12 @@ static void devm_memremap_pages_release(
}
/* pages are dead and unused, undo the arch mapping */
+ lock_device_hotplug();
mem_hotplug_begin();
arch_remove_memory(res->start, resource_size(res));
mem_hotplug_done();
+ unlock_device_hotplug();
+
untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
pgmap_radix_release(res);
dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
@@ -374,9 +377,11 @@ void *devm_memremap_pages(struct device
if (error)
goto err_pfn_remap;
+ lock_device_hotplug();
mem_hotplug_begin();
error = arch_add_memory(nid, res->start, resource_size(res), true);
mem_hotplug_done();
+ unlock_device_hotplug();
if (error)
goto err_add_memory;
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
mm-fix-type-width-of-section-to-from-pfn-conversion-macros.patch
mm-devm_memremap_pages-use-multi-order-radix-for-zone_device-lookups.patch
mm-introduce-struct-mem_section_usage-to-track-partial-population-of-a-section.patch
mm-introduce-common-definitions-for-the-size-and-mask-of-a-section.patch
mm-cleanup-sparse_init_one_section-return-value.patch
mm-track-active-portions-of-a-section-at-boot.patch
mm-fix-register_new_memory-zone-type-detection.patch
mm-convert-kmalloc_section_memmap-to-populate_section_memmap.patch
mm-prepare-for-hot-add-remove-of-sub-section-ranges.patch
mm-support-section-unaligned-zone_device-memory-ranges.patch
mm-support-section-unaligned-zone_device-memory-ranges-fix-2.patch
mm-enable-section-unaligned-devm_memremap_pages.patch
libnvdimm-pfn-dax-stop-padding-pmem-namespaces-to-section-alignment.patch
mm-fix-get_user_pages-vs-device-dax-pud-mappings.patch
mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_begin-done.patch
mm-validate-device_hotplug-is-held-for-memory-hotplug.patch
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