mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done} (b5d24fda) · Commits · 戴 / test

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: ("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>

kernel/memremap.c

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -246,9 +246,13 @@ static void devm_memremap_pages_release(struct device dev, void data)
	/* pages are dead and unused, undo the arch mapping */		/* pages are dead and unused, undo the arch mapping */
	align_start = res->start & ~(SECTION_SIZE - 1);		align_start = res->start & ~(SECTION_SIZE - 1);
	align_size = ALIGN(resource_size(res), SECTION_SIZE);		align_size = ALIGN(resource_size(res), SECTION_SIZE);

			lock_device_hotplug();
	mem_hotplug_begin();		mem_hotplug_begin();
	arch_remove_memory(align_start, align_size);		arch_remove_memory(align_start, align_size);
	mem_hotplug_done();		mem_hotplug_done();
			unlock_device_hotplug();

	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);		untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
	pgmap_radix_release(res);		pgmap_radix_release(res);
	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,		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)		if (error)
	goto err_pfn_remap;		goto err_pfn_remap;

			lock_device_hotplug();
	mem_hotplug_begin();		mem_hotplug_begin();
	error = arch_add_memory(nid, align_start, align_size, true);		error = arch_add_memory(nid, align_start, align_size, true);
	mem_hotplug_done();		mem_hotplug_done();
			unlock_device_hotplug();
	if (error)		if (error)
	goto err_add_memory;		goto err_add_memory;

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