[PATCH] libnvdimm, pfn: fix memmap reservation size versus 4K alignment

From: Dan Williams
Date: Sat Feb 04 2017 - 18:14:43 EST


When vmemmap_populate() allocates space for the memmap it does so in 2MB
sized chunks. The libnvdimm-pfn driver incorrectly accounts for this
when the alignment of the device is set to 4K. When this happens we
trigger memory allocation failures in altmap_alloc_block_buf() and
trigger warnings of the form:

WARNING: CPU: 0 PID: 3376 at arch/x86/mm/init_64.c:656 arch_add_memory+0xe4/0xf0
[..]
Call Trace:
dump_stack+0x86/0xc3
__warn+0xcb/0xf0
warn_slowpath_null+0x1d/0x20
arch_add_memory+0xe4/0xf0
devm_memremap_pages+0x29b/0x4e0

Fixes: 315c562536c4 ("libnvdimm, pfn: add 'align' attribute, default to HPAGE_SIZE")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/nvdimm/pfn_devs.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index a2ac9e641aa9..6c033c9a2f06 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -627,15 +627,12 @@ static int nd_pfn_init(struct nd_pfn *nd_pfn)
size = resource_size(&nsio->res);
npfns = (size - start_pad - end_trunc - SZ_8K) / SZ_4K;
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 + dax_label_reserve,
- nd_pfn->align) - start;
+ offset = ALIGN(start + SZ_8K + 64 * npfns + dax_label_reserve,
+ max(nd_pfn->align, HPAGE_SIZE)) - start;
} else if (nd_pfn->mode == PFN_MODE_RAM)
offset = ALIGN(start + SZ_8K + dax_label_reserve,
nd_pfn->align) - start;