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authorAlistair Popple <apopple@nvidia.com>2021-05-06 18:05:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-07 00:26:33 -0700
commit56fd94919b8bfdbe162f78920b4ebc72b4ce2f39 (patch)
treebb2478d663d1e1a751732b2d75319e58aae317c0 /kernel/resource.c
parent63cdafe0af982e7da9ded37ccf21109a02bc6832 (diff)
kernel/resource: fix locking in request_free_mem_region
request_free_mem_region() is used to find an empty range of physical addresses for hotplugging ZONE_DEVICE memory. It does this by iterating over the range of possible addresses using region_intersects() to see if the range is free before calling request_mem_region() to allocate the region. However the resource_lock is dropped between these two calls meaning by the time request_mem_region() is called in request_free_mem_region() another thread may have already reserved the requested region. This results in unexpected failures and a message in the kernel log from hitting this condition: /* * mm/hmm.c reserves physical addresses which then * become unavailable to other users. Conflicts are * not expected. Warn to aid debugging if encountered. */ if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) { pr_warn("Unaddressable device %s %pR conflicts with %pR", conflict->name, conflict, res); These unexpected failures can be corrected by holding resource_lock across the two calls. This also requires memory allocation to be performed prior to taking the lock. Link: https://lkml.kernel.org/r/20210419070109.4780-3-apopple@nvidia.com Signed-off-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Muchun Song <smuchun@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/resource.c')
-rw-r--r--kernel/resource.c45
1 files changed, 38 insertions, 7 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index c8e473b68f17..028a5ab18818 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1780,25 +1780,56 @@ static struct resource *__request_free_mem_region(struct device *dev,
{
resource_size_t end, addr;
struct resource *res;
+ struct region_devres *dr = NULL;
size = ALIGN(size, 1UL << PA_SECTION_SHIFT);
end = min_t(unsigned long, base->end, (1UL << MAX_PHYSMEM_BITS) - 1);
addr = end - size + 1UL;
+ res = alloc_resource(GFP_KERNEL);
+ if (!res)
+ return ERR_PTR(-ENOMEM);
+
+ if (dev) {
+ dr = devres_alloc(devm_region_release,
+ sizeof(struct region_devres), GFP_KERNEL);
+ if (!dr) {
+ free_resource(res);
+ return ERR_PTR(-ENOMEM);
+ }
+ }
+
+ write_lock(&resource_lock);
for (; addr > size && addr >= base->start; addr -= size) {
- if (region_intersects(addr, size, 0, IORES_DESC_NONE) !=
+ if (__region_intersects(addr, size, 0, IORES_DESC_NONE) !=
REGION_DISJOINT)
continue;
- if (dev)
- res = devm_request_mem_region(dev, addr, size, name);
- else
- res = request_mem_region(addr, size, name);
- if (!res)
- return ERR_PTR(-ENOMEM);
+ if (!__request_region_locked(res, &iomem_resource, addr, size,
+ name, 0))
+ break;
+
+ if (dev) {
+ dr->parent = &iomem_resource;
+ dr->start = addr;
+ dr->n = size;
+ devres_add(dev, dr);
+ }
+
res->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
+ write_unlock(&resource_lock);
+
+ /*
+ * A driver is claiming this region so revoke any mappings.
+ */
+ revoke_iomem(res);
return res;
}
+ write_unlock(&resource_lock);
+
+ free_resource(res);
+ if (dr)
+ devres_free(dr);
return ERR_PTR(-ERANGE);
}