linux-kernel - [PATCH] libnvdimm, pfn: fix memmap reservation sizing

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Message-ID: <146205014370.20579.17366708223180896686.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:	Sat, 30 Apr 2016 14:02:23 -0700
From:	Dan Williams <dan.j.williams@...el.com>
To:	linux-nvdimm@...ts.01.org
Cc:	Namratha Kothapalli <namratha.n.kothapalli@...el.com>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH] libnvdimm, pfn: fix memmap reservation sizing

When configuring a pfn-device instance to allocate the memmap array it
needs to account for the fact that vmemmap_populate_hugepages()
allocates struct page blocks in HPAGE_SIZE chunks.  We need to align the
reserved area size to 2MB otherwise arch_add_memory() runs out of memory
while establishing the memmap:

 WARNING: CPU: 0 PID: 496 at arch/x86/mm/init_64.c:704 arch_add_memory+0xe7/0xf0
 [..]
 Call Trace:
  [<ffffffff8148bdb3>] dump_stack+0x85/0xc2
  [<ffffffff810a749b>] __warn+0xcb/0xf0
  [<ffffffff810a75cd>] warn_slowpath_null+0x1d/0x20
  [<ffffffff8106a497>] arch_add_memory+0xe7/0xf0
  [<ffffffff811d2097>] devm_memremap_pages+0x287/0x450
  [<ffffffff811d1ffa>] ? devm_memremap_pages+0x1ea/0x450
  [<ffffffffa0000298>] __wrap_devm_memremap_pages+0x58/0x70 [nfit_test_iomap]
  [<ffffffffa0047a58>] pmem_attach_disk+0x318/0x420 [nd_pmem]
  [<ffffffffa0047bcf>] nd_pmem_probe+0x6f/0x90 [nd_pmem]
  [<ffffffffa0009469>] nvdimm_bus_probe+0x69/0x110 [libnvdimm]
 [..]
  ndbus0: nd_pmem.probe(pfn3.0) = -12
 nd_pmem: probe of pfn3.0 failed with error -12
libndctl: ndctl_pfn_enable: pfn3.0: failed to enable

Reported-by: Namratha Kothapalli <namratha.n.kothapalli@...el.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/nvdimm/pmem.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index f798899338ed..5101f3ab4f29 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -397,10 +397,17 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
 	 */
 	start += start_pad;
 	npfns = (pmem->size - start_pad - end_trunc - SZ_8K) / SZ_4K;
-	if (nd_pfn->mode == PFN_MODE_PMEM)
-		offset = ALIGN(start + SZ_8K + 64 * npfns, nd_pfn->align)
+	if (nd_pfn->mode == PFN_MODE_PMEM) {
+		unsigned long memmap_size;
+
+		/*
+		 * vmemmap_populate_hugepages() allocates the memmap array in
+		 * HPAGE_SIZE chunks.
+		 */
+		memmap_size = ALIGN(64 * npfns, HPAGE_SIZE);
+		offset = ALIGN(start + SZ_8K + memmap_size, nd_pfn->align)
 			- start;
-	else if (nd_pfn->mode == PFN_MODE_RAM)
+	} else if (nd_pfn->mode == PFN_MODE_RAM)
 		offset = ALIGN(start + SZ_8K, nd_pfn->align) - start;
 	else
 		goto err;