Patch "libnvdimm, pfn: fix memmap reservation size versus 4K alignment" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
libnvdimm-pfn-fix-memmap-reservation-size-versus-4k-alignment.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dan Williams <[email protected]>
Date: Sat, 4 Feb 2017 14:47:31 -0800
Subject: libnvdimm, pfn: fix memmap reservation size versus 4K alignment

From: Dan Williams <[email protected]>

commit bfb34527a32a1a576d9bfb7026d3ab0369a6cd60 upstream.

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

---
 drivers/nvdimm/pfn_devs.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

@@ -627,15 +627,12 @@ static int nd_pfn_init(struct nd_pfn *nd
 	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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/libnvdimm-namespace-do-not-delete-namespace-id-0.patch queue-4.9/libnvdimm-pfn-fix-memmap-reservation-size-versus-4k-alignment.patch queue-4.9/acpi-nfit-fix-acpi_nfit_flush_probe-crash.patch