[PATCH] libnvdimm, pfn: fix memmap reservation sizing

From: Dan Williams
Date: Sat Apr 30 2016 - 17:03:16 EST


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@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
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;