The patch below does not apply to the 4.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 949b93250a566cc7a578b4f829cf76b70d19a62c Mon Sep 17 00:00:00 2001

From: Dan Williams dan.j.williams@intel.com Date: Tue, 6 Feb 2018 19:34:11 -0800 Subject: [PATCH] memremap: fix softlockup reports at teardown MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

The cond_resched() currently in the setup path needs to be duplicated in the teardown path. Rather than require each instance of for_each_device_pfn() to open code the same sequence, embed it in the helper.

Link: https://github.com/intel/ixpdimm_sw/issues/11 Cc: "Jérôme Glisse" jglisse@redhat.com Cc: Michal Hocko mhocko@suse.com Cc: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org Fixes: 71389703839e ("mm, zone_device: Replace {get, put}_zone_device_page()...") Signed-off-by: Dan Williams dan.j.williams@intel.com

diff --git a/kernel/memremap.c b/kernel/memremap.c index 4849be5f9b3c..4dd4274cabe2 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -275,8 +275,15 @@ static unsigned long pfn_end(struct dev_pagemap *pgmap) return (res->start + resource_size(res)) >> PAGE_SHIFT; }

+static unsigned long pfn_next(unsigned long pfn) +{ + if (pfn % 1024 == 0) + cond_resched(); + return pfn + 1; +} + #define for_each_device_pfn(pfn, map) \ - for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++) + for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn))

static void devm_memremap_pages_release(void *data) { @@ -337,10 +344,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) resource_size_t align_start, align_size, align_end; struct vmem_altmap *altmap = pgmap->altmap_valid ? &pgmap->altmap : NULL; + struct resource *res = &pgmap->res; unsigned long pfn, pgoff, order; pgprot_t pgprot = PAGE_KERNEL; - int error, nid, is_ram, i = 0; - struct resource *res = &pgmap->res; + int error, nid, is_ram;

align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) @@ -409,8 +416,6 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) list_del(&page->lru); page->pgmap = pgmap; percpu_ref_get(pgmap->ref); - if (!(++i % 1024)) - cond_resched(); }

devm_add_action(dev, devm_memremap_pages_release, pgmap);