4.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dan Williams <[email protected]> commit b5d24fda9c3dce51fcb4eee459550a458eaaf1e2 upstream. 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. [[email protected]: v2] Link: http://lkml.kernel.org/r/148728203365.38457.17804568297887708345.st...@dwillia2-desk3.amr.corp.intel.com Link: http://lkml.kernel.org/r/148693885680.16345.17802627926777862337.st...@dwillia2-desk3.amr.corp.intel.com Fixes: f931ab479dd2 ("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}") Signed-off-by: Dan Williams <[email protected]> Reported-by: Ben Hutchings <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Toshi Kani <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Logan Gunthorpe <[email protected]> Cc: Masayoshi Mizuma <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/memremap.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -246,9 +246,13 @@ static void devm_memremap_pages_release( /* 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 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;
