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authorDan Williams <dan.j.williams@intel.com>2017-02-24 14:55:45 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-24 17:46:53 -0800
commitb5d24fda9c3dce51fcb4eee459550a458eaaf1e2 (patch)
treeaad811ffd2581cd9d29c5995615a8b77cfe2859b
parent299c517adb903ddd376dd103fcc9dcfff3d4728b (diff)
downloadlinux-b5d24fda9c3dce51fcb4eee459550a458eaaf1e2.tar.bz2
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: f931ab479dd2 ("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>
-rw-r--r--kernel/memremap.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 9ecedc28b928..06123234f118 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -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;