The patch titled
Subject: memremap: Fix reference count for pgmap in devm_memremap_pages
has been added to the -mm tree. Its filename is
mm-defer-zone_device-page-initialization-to-the-point-where-we-init-pgmap-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-defer-zone_device-page-initialization-to-the-point-where-we-init-pgmap-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-defer-zone_device-page-initialization-to-the-point-where-we-init-pgmap-fix.patch
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------------------------------------------------------
From: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Subject: memremap: Fix reference count for pgmap in devm_memremap_pages
In the earlier patch "mm: defer ZONE_DEVICE page initialization to the
point where we init pgmap" I had overlooked the reference count that was
being held per page on the pgmap. As a result on running the ndctl test
"create.sh" we would call into devm_memremap_pages_release and encounter
the following percpu reference count error and hang:
WARNING: CPU: 30 PID: 0 at lib/percpu-refcount.c:155
percpu_ref_switch_to_atomic_rcu+0xf3/0x120
This patch addresses that by performing an update for all of the device
PFNs in a single call. In my testing this seems to resolve the issue
while still allowing us to retain the improvements seen in memory
initialization.
Link: http://lkml.kernel.org/r/20181008233404.1909.37302.stgit@localhost.localdomain
Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Reported-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Tested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/memremap.c | 1 +
1 file changed, 1 insertion(+)
--- a/kernel/memremap.c~mm-defer-zone_device-page-initialization-to-the-point-where-we-init-pgmap-fix
+++ a/kernel/memremap.c
@@ -263,6 +263,7 @@ void *devm_memremap_pages(struct device
memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
align_start >> PAGE_SHIFT,
align_size >> PAGE_SHIFT, pgmap);
+ percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap));
devm_add_action(dev, devm_memremap_pages_release, pgmap);
_
Patches currently in -mm which might be from alexander.h.duyck@xxxxxxxxxxxxxxx are
mm-provide-kernel-parameter-to-allow-disabling-page-init-poisoning.patch
mm-create-non-atomic-version-of-setpagereserved-for-init-use.patch
mm-defer-zone_device-page-initialization-to-the-point-where-we-init-pgmap.patch
mm-defer-zone_device-page-initialization-to-the-point-where-we-init-pgmap-fix.patch
mm-remove-config_no_bootmem-fix.patch
