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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.

[dan.j.williams@intel.com: v2]
  Link: http://lkml.kernel.org/r/148728203365.38457.17804568297887708345.stgit@dwillia2-desk3.amr.corp.intel.com
Link: http://lkml.kernel.org/r/148693885680.16345.17802627926777862337.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: f931ab479d ("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Williams 2017-02-24 14:55:45 -08:00 committed by Linus Torvalds
parent 299c517adb
commit b5d24fda9c
1 changed files with 6 additions and 0 deletions
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6
kernel/memremap.c
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@ -246,9 +246,13 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
/* pages are dead and unused, undo the arch mapping */
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(resource_size(res), SECTION_SIZE);
lock_device_hotplug();
mem_hotplug_begin();
arch_remove_memory(align_start, align_size);
mem_hotplug_done();
unlock_device_hotplug();
untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
pgmap_radix_release(res);
dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
@ -360,9 +364,11 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
if (error)
goto err_pfn_remap;
lock_device_hotplug();
mem_hotplug_begin();
error = arch_add_memory(nid, align_start, align_size, true);
mem_hotplug_done();
unlock_device_hotplug();
if (error)
goto err_add_memory;