The patch titled
Subject: device-dax: kill dax_kmem_res
has been added to the -mm tree. Its filename is
device-dax-kill-dax_kmem_res.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/device-dax-kill-dax_kmem_res.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/device-dax-kill-dax_kmem_res.patch
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a) Consider who else should be cc'ed
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c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
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------------------------------------------------------
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: device-dax: kill dax_kmem_res
Several related issues around this unneeded attribute:
- The dax_kmem_res property allows the kmem driver to stash the adjusted
resource range that was used for the hotplug operation, but that can be
recalculated from the original base range.
- kmem is using an open coded release_resource() + kfree() when an
idiomatic release_mem_region() is sufficient.
- The driver managed resource need only manage the busy flag. Other
flags are of no concern to the kmem driver. In fact if kmem inherits
some memory range that add_memory_driver_managed() rejects that is a
memory-hotplug-core policy that the driver is in no position to
override.
- The implementation trusts that failed remove_memory() results in the
entire resource range remaining pinned busy. The driver need not make
that layering violation assumption and just maintain the busy state in
its local resource.
- The "Hot-remove not yet implemented." comment is stale since hotremove
support is now included.
Link: https://lkml.kernel.org/r/159643100485.4062302.976628339798536960.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Ben Skeggs <bskeggs@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brice Goglin <Brice.Goglin@xxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
Cc: Jia He <justin.he@xxxxxxx>
Cc: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/dax/dax-private.h | 3
drivers/dax/kmem.c | 123 ++++++++++++++++--------------------
2 files changed, 58 insertions(+), 68 deletions(-)
--- a/drivers/dax/dax-private.h~device-dax-kill-dax_kmem_res
+++ a/drivers/dax/dax-private.h
@@ -42,8 +42,6 @@ struct dax_region {
* @dev - device core
* @pgmap - pgmap for memmap setup / lifetime (driver owned)
* @range: resource range for the instance
- * @dax_mem_res: physical address range of hotadded DAX memory
- * @dax_mem_name: name for hotadded DAX memory via add_memory_driver_managed()
*/
struct dev_dax {
struct dax_region *region;
@@ -52,7 +50,6 @@ struct dev_dax {
struct device dev;
struct dev_pagemap *pgmap;
struct range range;
- struct resource *dax_kmem_res;
};
static inline u64 range_len(struct range *range)
--- a/drivers/dax/kmem.c~device-dax-kill-dax_kmem_res
+++ a/drivers/dax/kmem.c
@@ -19,16 +19,24 @@ static const char *kmem_name;
/* Set if any memory will remain added when the driver will be unloaded. */
static bool any_hotremove_failed;
+static struct range dax_kmem_range(struct dev_dax *dev_dax)
+{
+ struct range range;
+
+ /* memory-block align the hotplug range */
+ range.start = ALIGN(dev_dax->range.start, memory_block_size_bytes());
+ range.end = ALIGN_DOWN(dev_dax->range.end + 1,
+ memory_block_size_bytes()) - 1;
+ return range;
+}
+
int dev_dax_kmem_probe(struct device *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
- struct range *range = &dev_dax->range;
- resource_size_t kmem_start;
- resource_size_t kmem_size;
- resource_size_t kmem_end;
- struct resource *new_res;
- const char *new_res_name;
- int numa_node;
+ struct range range = dax_kmem_range(dev_dax);
+ int numa_node = dev_dax->target_node;
+ struct resource *res;
+ char *res_name;
int rc;
/*
@@ -37,109 +45,94 @@ int dev_dax_kmem_probe(struct device *de
* could be mixed in a node with faster memory, causing
* unavoidable performance issues.
*/
- numa_node = dev_dax->target_node;
if (numa_node < 0) {
dev_warn(dev, "rejecting DAX region with invalid node: %d\n",
numa_node);
return -EINVAL;
}
- /* Hotplug starting at the beginning of the next block: */
- kmem_start = ALIGN(range->start, memory_block_size_bytes());
-
- kmem_size = range_len(range);
- /* Adjust the size down to compensate for moving up kmem_start: */
- kmem_size -= kmem_start - range->start;
- /* Align the size down to cover only complete blocks: */
- kmem_size &= ~(memory_block_size_bytes() - 1);
- kmem_end = kmem_start + kmem_size;
-
- new_res_name = kstrdup(dev_name(dev), GFP_KERNEL);
- if (!new_res_name)
+ res_name = kstrdup(dev_name(dev), GFP_KERNEL);
+ if (!res_name)
return -ENOMEM;
- /* Region is permanently reserved if hotremove fails. */
- new_res = request_mem_region(kmem_start, kmem_size, new_res_name);
- if (!new_res) {
- dev_warn(dev, "could not reserve region [%pa-%pa]\n",
- &kmem_start, &kmem_end);
- kfree(new_res_name);
+ res = request_mem_region(range.start, range_len(&range), res_name);
+ if (!res) {
+ dev_warn(dev, "could not reserve region [%#llx-%#llx]\n",
+ range.start, range.end);
+ kfree(res_name);
return -EBUSY;
}
/*
- * Set flags appropriate for System RAM. Leave ..._BUSY clear
- * so that add_memory() can add a child resource. Do not
- * inherit flags from the parent since it may set new flags
- * unknown to us that will break add_memory() below.
+ * Temporarily clear busy to allow add_memory_driver_managed()
+ * to claim it.
*/
- new_res->flags = IORESOURCE_SYSTEM_RAM;
+ res->flags &= ~IORESOURCE_BUSY;
/*
* Ensure that future kexec'd kernels will not treat this as RAM
* automatically.
*/
- rc = add_memory_driver_managed(numa_node, new_res->start,
- resource_size(new_res), kmem_name);
+ rc = add_memory_driver_managed(numa_node, res->start,
+ resource_size(res), kmem_name);
+
+ res->flags |= IORESOURCE_BUSY;
if (rc) {
- release_resource(new_res);
- kfree(new_res);
- kfree(new_res_name);
+ release_mem_region(range.start, range_len(&range));
+ kfree(res_name);
return rc;
}
- dev_dax->dax_kmem_res = new_res;
+
+ dev_set_drvdata(dev, res_name);
return 0;
}
#ifdef CONFIG_MEMORY_HOTREMOVE
-static int dev_dax_kmem_remove(struct device *dev)
+static void dax_kmem_release(struct dev_dax *dev_dax)
{
- struct dev_dax *dev_dax = to_dev_dax(dev);
- struct resource *res = dev_dax->dax_kmem_res;
- resource_size_t kmem_start = res->start;
- resource_size_t kmem_size = resource_size(res);
- const char *res_name = res->name;
int rc;
+ struct device *dev = &dev_dax->dev;
+ const char *res_name = dev_get_drvdata(dev);
+ struct range range = dax_kmem_range(dev_dax);
/*
* We have one shot for removing memory, if some memory blocks were not
* offline prior to calling this function remove_memory() will fail, and
* there is no way to hotremove this memory until reboot because device
- * unbind will succeed even if we return failure.
+ * unbind will proceed regardless of the remove_memory result.
*/
- rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size);
- if (rc) {
- any_hotremove_failed = true;
- dev_err(dev,
- "DAX region %pR cannot be hotremoved until the next reboot\n",
- res);
- return rc;
+ rc = remove_memory(dev_dax->target_node, range.start, range_len(&range));
+ if (rc == 0) {
+ release_mem_region(range.start, range_len(&range));
+ dev_set_drvdata(dev, NULL);
+ kfree(res_name);
+ return;
}
- /* Release and free dax resources */
- release_resource(res);
- kfree(res);
- kfree(res_name);
- dev_dax->dax_kmem_res = NULL;
-
- return 0;
+ any_hotremove_failed = true;
+ dev_err(dev, "%#llx-%#llx cannot be hotremoved until the next reboot\n",
+ range.start, range.end);
}
#else
-static int dev_dax_kmem_remove(struct device *dev)
+static void dax_kmem_release(struct dev_dax *dev_dax)
{
/*
- * Without hotremove purposely leak the request_mem_region() for the
- * device-dax range and return '0' to ->remove() attempts. The removal
- * of the device from the driver always succeeds, but the region is
- * permanently pinned as reserved by the unreleased
- * request_mem_region().
+ * Without hotremove purposely leak the request_mem_region() for
+ * the device-dax range attempts. The removal of the device from
+ * the driver always succeeds, but the region is permanently
+ * pinned as reserved by the unreleased request_mem_region().
*/
any_hotremove_failed = true;
- return 0;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
+static int dev_dax_kmem_remove(struct device *dev)
+{
+ dax_kmem_release(to_dev_dax(dev));
+ return 0;
+}
+
static struct dax_device_driver device_dax_kmem_driver = {
.drv = {
.probe = dev_dax_kmem_probe,
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
x86-numa-cleanup-configuration-dependent-command-line-options.patch
x86-numa-add-nohmat-option.patch
efi-fake_mem-arrange-for-a-resource-entry-per-efi_fake_mem-instance.patch
acpi-hmat-refactor-hmat_register_target_device-to-hmem_register_device.patch
resource-report-parent-to-walk_iomem_res_desc-callback.patch
mm-memory_hotplug-introduce-default-phys_to_target_node-implementation.patch
acpi-hmat-attach-a-device-for-each-soft-reserved-range.patch
device-dax-drop-the-dax_regionpfn_flags-attribute.patch
device-dax-move-instance-creation-parameters-to-struct-dev_dax_data.patch
device-dax-make-pgmap-optional-for-instance-creation.patch
device-dax-kill-dax_kmem_res.patch
device-dax-add-an-allocation-interface-for-device-dax-instances.patch
device-dax-introduce-seed-devices.patch
drivers-base-make-device_find_child_by_name-compatible-with-sysfs-inputs.patch
device-dax-add-resize-support.patch
mm-memremap_pages-convert-to-struct-range.patch
mm-memremap_pages-support-multiple-ranges-per-invocation.patch
device-dax-add-dis-contiguous-resource-support.patch
device-dax-introduce-mapping-devices.patch
