* [PATCH v7 0/3] mm: use memmap_on_memory semantics for dax/kmem
@ 2023-10-25 22:44 Vishal Verma
2023-10-25 22:44 ` [PATCH v7 1/3] mm/memory_hotplug: replace an open-coded kmemdup() in add_memory_resource() Vishal Verma
` (2 more replies)
0 siblings, 3 replies; 9+ messages in thread
From: Vishal Verma @ 2023-10-25 22:44 UTC (permalink / raw
To: Andrew Morton, David Hildenbrand, Oscar Salvador, Dan Williams,
Dave Jiang
Cc: linux-kernel, linux-mm, nvdimm, linux-cxl, Huang Ying,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer, Vishal Verma, Jonathan Cameron
The dax/kmem driver can potentially hot-add large amounts of memory
originating from CXL memory expanders, or NVDIMMs, or other 'device
memories'. There is a chance there isn't enough regular system memory
available to fit the memmap for this new memory. It's therefore
desirable, if all other conditions are met, for the kmem managed memory
to place its memmap on the newly added memory itself.
The main hurdle for accomplishing this for kmem is that memmap_on_memory
can only be done if the memory being added is equal to the size of one
memblock. To overcome this, allow the hotplug code to split an add_memory()
request into memblock-sized chunks, and try_remove_memory() to also
expect and handle such a scenario.
Patch 1 replaces an open-coded kmemdup()
Patch 2 teaches the memory_hotplug code to allow for splitting
add_memory() and remove_memory() requests over memblock sized chunks.
Patch 3 allows the dax region drivers to request memmap_on_memory
semantics. CXL dax regions default this to 'on', all others default to
off to keep existing behavior unchanged.
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
Changes in v7:
- Make the add_memory_resource() flow symmetrical w.r.t. try_remove_memory()
in terms of how the altmap path is taken (David Hildenbrand)
- Move a comment, clean up usage of 'memblock' vs. 'memory_block'
(David Hildenbrand)
- Don't use the altmap path for the mhp_supports_memmap_on_memory(memblock_size) == false
case (Huang Ying)
- Link to v6: https://lore.kernel.org/r/20231016-vv-kmem_memmap-v6-0-078f0d3c0371@intel.com
Changes in v6:
- Add a prep patch to replace an open coded kmemdup in
add_memory_resource() (Dan Williams)
- Fix ordering of firmware_map_remove w.r.t taking the hotplug lock
(David Hildenbrand)
- Remove unused 'nid' variable, and a stray whitespace (David Hildenbrand)
- Clean up and simplify the altmap vs non-altmap paths for
try_remove_memory (David Hildenbrand)
- Add a note to the changelog in patch 1 linking to the PUD mappings
proposal (David Hildenbrand)
- Remove the new sysfs ABI from the kmem/dax drivers until ABI
documentation for /sys/bus/dax can be established (will split this out
into a separate patchset) (Dan Williams)
- Link to v5: https://lore.kernel.org/r/20231005-vv-kmem_memmap-v5-0-a54d1981f0a3@intel.com
Changes in v5:
- Separate out per-memblock operations from per memory block operations
in try_remove_memory(), and rename the inner function appropriately.
This does expand the scope of the memory hotplug lock to include
remove_memory_block_devices(), but the alternative was to drop the
lock in the inner function separately for each iteration, and then
re-acquire it in try_remove_memory() creating a small window where
the lock isn't held. (David Hildenbrand)
- Remove unnecessary rc check from the memmap_on_memory_store sysfs
helper in patch 2 (Dan Carpenter)
- Link to v4: https://lore.kernel.org/r/20230928-vv-kmem_memmap-v4-0-6ff73fec519a@intel.com
Changes in v4:
- Rebase to Aneesh's PPC64 memmap_on_memory series v8 [2].
- Tweak a goto / error path in add_memory_create_devices() (Jonathan)
- Retain the old behavior for dax devices, only default to
memmap_on_memory for CXL (Jonathan)
- Link to v3: https://lore.kernel.org/r/20230801-vv-kmem_memmap-v3-0-406e9aaf5689@intel.com
[2]: https://lore.kernel.org/linux-mm/20230808091501.287660-1-aneesh.kumar@linux.ibm.com
Changes in v3:
- Rebase on Aneesh's patches [1]
- Drop Patch 1 - it is not needed since [1] allows for dynamic setting
of the memmap_on_memory param (David)
- Link to v2: https://lore.kernel.org/r/20230720-vv-kmem_memmap-v2-0-88bdaab34993@intel.com
[1]: https://lore.kernel.org/r/20230801044116.10674-1-aneesh.kumar@linux.ibm.com
Changes in v2:
- Drop the patch to create an override path for the memmap_on_memory
module param (David)
- Move the chunking into memory_hotplug.c so that any caller of
add_memory() can request this behavior. (David)
- Handle remove_memory() too. (David, Ying)
- Add a sysfs control in the kmem driver for memmap_on_memory semantics
(David, Jonathan)
- Add a #else case to define mhp_supports_memmap_on_memory() if
CONFIG_MEMORY_HOTPLUG is unset. (0day report)
- Link to v1: https://lore.kernel.org/r/20230613-vv-kmem_memmap-v1-0-f6de9c6af2c6@intel.com
---
Vishal Verma (3):
mm/memory_hotplug: replace an open-coded kmemdup() in add_memory_resource()
mm/memory_hotplug: split memmap_on_memory requests across memblocks
dax/kmem: allow kmem to add memory with memmap_on_memory
drivers/dax/bus.h | 1 +
drivers/dax/dax-private.h | 1 +
drivers/dax/bus.c | 3 +
drivers/dax/cxl.c | 1 +
drivers/dax/hmem/hmem.c | 1 +
drivers/dax/kmem.c | 8 +-
drivers/dax/pmem.c | 1 +
mm/memory_hotplug.c | 207 ++++++++++++++++++++++++++++++++--------------
8 files changed, 158 insertions(+), 65 deletions(-)
---
base-commit: 25b5b1a0646c3d39e1d885e27c10be1c9e202bf2
change-id: 20230613-vv-kmem_memmap-5483c8d04279
Best regards,
--
Vishal Verma <vishal.l.verma@intel.com>
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v7 1/3] mm/memory_hotplug: replace an open-coded kmemdup() in add_memory_resource()
2023-10-25 22:44 [PATCH v7 0/3] mm: use memmap_on_memory semantics for dax/kmem Vishal Verma
@ 2023-10-25 22:44 ` Vishal Verma
2023-10-25 22:44 ` [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks Vishal Verma
2023-10-25 22:44 ` [PATCH v7 3/3] dax/kmem: allow kmem to add memory with memmap_on_memory Vishal Verma
2 siblings, 0 replies; 9+ messages in thread
From: Vishal Verma @ 2023-10-25 22:44 UTC (permalink / raw
To: Andrew Morton, David Hildenbrand, Oscar Salvador, Dan Williams,
Dave Jiang
Cc: linux-kernel, linux-mm, nvdimm, linux-cxl, Huang Ying,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer, Vishal Verma
A review of the memmap_on_memory modifications to add_memory_resource()
revealed an instance of an open-coded kmemdup(). Replace it with
kmemdup().
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Reported-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
mm/memory_hotplug.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f8d3e7427e32..6be7de9efa55 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1439,11 +1439,11 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
if (mhp_flags & MHP_MEMMAP_ON_MEMORY) {
if (mhp_supports_memmap_on_memory(size)) {
mhp_altmap.free = memory_block_memmap_on_memory_pages();
- params.altmap = kmalloc(sizeof(struct vmem_altmap), GFP_KERNEL);
+ params.altmap = kmemdup(&mhp_altmap,
+ sizeof(struct vmem_altmap),
+ GFP_KERNEL);
if (!params.altmap)
goto error;
-
- memcpy(params.altmap, &mhp_altmap, sizeof(mhp_altmap));
}
/* fallback to not using altmap */
}
--
2.41.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks
2023-10-25 22:44 [PATCH v7 0/3] mm: use memmap_on_memory semantics for dax/kmem Vishal Verma
2023-10-25 22:44 ` [PATCH v7 1/3] mm/memory_hotplug: replace an open-coded kmemdup() in add_memory_resource() Vishal Verma
@ 2023-10-25 22:44 ` Vishal Verma
2023-10-30 2:46 ` Huang, Ying
2023-10-30 10:20 ` David Hildenbrand
2023-10-25 22:44 ` [PATCH v7 3/3] dax/kmem: allow kmem to add memory with memmap_on_memory Vishal Verma
2 siblings, 2 replies; 9+ messages in thread
From: Vishal Verma @ 2023-10-25 22:44 UTC (permalink / raw
To: Andrew Morton, David Hildenbrand, Oscar Salvador, Dan Williams,
Dave Jiang
Cc: linux-kernel, linux-mm, nvdimm, linux-cxl, Huang Ying,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer, Vishal Verma
The MHP_MEMMAP_ON_MEMORY flag for hotplugged memory is restricted to
'memblock_size' chunks of memory being added. Adding a larger span of
memory precludes memmap_on_memory semantics.
For users of hotplug such as kmem, large amounts of memory might get
added from the CXL subsystem. In some cases, this amount may exceed the
available 'main memory' to store the memmap for the memory being added.
In this case, it is useful to have a way to place the memmap on the
memory being added, even if it means splitting the addition into
memblock-sized chunks.
Change add_memory_resource() to loop over memblock-sized chunks of
memory if caller requested memmap_on_memory, and if other conditions for
it are met. Teach try_remove_memory() to also expect that a memory
range being removed might have been split up into memblock sized chunks,
and to loop through those as needed.
This does preclude being able to use PUD mappings in the direct map; a
proposal to how this could be optimized in the future is laid out
here[1].
[1]: https://lore.kernel.org/linux-mm/b6753402-2de9-25b2-36e9-eacd49752b19@redhat.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
mm/memory_hotplug.c | 209 ++++++++++++++++++++++++++++++++++++----------------
1 file changed, 144 insertions(+), 65 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6be7de9efa55..b97035193090 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1380,6 +1380,48 @@ static bool mhp_supports_memmap_on_memory(unsigned long size)
return arch_supports_memmap_on_memory(vmemmap_size);
}
+static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group,
+ u64 start, u64 size)
+{
+ unsigned long memblock_size = memory_block_size_bytes();
+ u64 cur_start;
+ int ret;
+
+ for (cur_start = start; cur_start < start + size;
+ cur_start += memblock_size) {
+ struct mhp_params params = { .pgprot =
+ pgprot_mhp(PAGE_KERNEL) };
+ struct vmem_altmap mhp_altmap = {
+ .base_pfn = PHYS_PFN(cur_start),
+ .end_pfn = PHYS_PFN(cur_start + memblock_size - 1),
+ };
+
+ mhp_altmap.free = memory_block_memmap_on_memory_pages();
+ params.altmap = kmemdup(&mhp_altmap, sizeof(struct vmem_altmap),
+ GFP_KERNEL);
+ if (!params.altmap)
+ return -ENOMEM;
+
+ /* call arch's memory hotadd */
+ ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms);
+ if (ret < 0) {
+ kfree(params.altmap);
+ return ret;
+ }
+
+ /* create memory block devices after memory was added */
+ ret = create_memory_block_devices(cur_start, memblock_size,
+ params.altmap, group);
+ if (ret) {
+ arch_remove_memory(cur_start, memblock_size, NULL);
+ kfree(params.altmap);
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
/*
* NOTE: The caller must call lock_device_hotplug() to serialize hotplug
* and online/offline operations (triggered e.g. by sysfs).
@@ -1390,10 +1432,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
{
struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
enum memblock_flags memblock_flags = MEMBLOCK_NONE;
- struct vmem_altmap mhp_altmap = {
- .base_pfn = PHYS_PFN(res->start),
- .end_pfn = PHYS_PFN(res->end),
- };
struct memory_group *group = NULL;
u64 start, size;
bool new_node = false;
@@ -1436,28 +1474,22 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
/*
* Self hosted memmap array
*/
- if (mhp_flags & MHP_MEMMAP_ON_MEMORY) {
- if (mhp_supports_memmap_on_memory(size)) {
- mhp_altmap.free = memory_block_memmap_on_memory_pages();
- params.altmap = kmemdup(&mhp_altmap,
- sizeof(struct vmem_altmap),
- GFP_KERNEL);
- if (!params.altmap)
- goto error;
+ if ((mhp_flags & MHP_MEMMAP_ON_MEMORY) &&
+ mhp_supports_memmap_on_memory(memory_block_size_bytes())) {
+ ret = create_altmaps_and_memory_blocks(nid, group, start, size);
+ if (ret)
+ goto error;
+ } else {
+ ret = arch_add_memory(nid, start, size, ¶ms);
+ if (ret < 0)
+ goto error;
+
+ /* create memory block devices after memory was added */
+ ret = create_memory_block_devices(start, size, NULL, group);
+ if (ret) {
+ arch_remove_memory(start, size, NULL);
+ goto error;
}
- /* fallback to not using altmap */
- }
-
- /* call arch's memory hotadd */
- ret = arch_add_memory(nid, start, size, ¶ms);
- if (ret < 0)
- goto error_free;
-
- /* create memory block devices after memory was added */
- ret = create_memory_block_devices(start, size, params.altmap, group);
- if (ret) {
- arch_remove_memory(start, size, NULL);
- goto error_free;
}
if (new_node) {
@@ -1494,8 +1526,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
walk_memory_blocks(start, size, NULL, online_memory_block);
return ret;
-error_free:
- kfree(params.altmap);
error:
if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
memblock_remove(start, size);
@@ -2076,6 +2106,16 @@ static int test_has_altmap_cb(struct memory_block *mem, void *arg)
return 0;
}
+static int count_memory_range_altmaps_cb(struct memory_block *mem, void *arg)
+{
+ u64 *num_altmaps = (u64 *)arg;
+
+ if (mem->altmap)
+ *num_altmaps += 1;
+
+ return 0;
+}
+
static int check_cpu_on_node(int nid)
{
int cpu;
@@ -2146,11 +2186,69 @@ void try_offline_node(int nid)
}
EXPORT_SYMBOL(try_offline_node);
-static int __ref try_remove_memory(u64 start, u64 size)
+static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size)
{
- struct memory_block *mem;
- int rc = 0, nid = NUMA_NO_NODE;
+ unsigned long memblock_size = memory_block_size_bytes();
struct vmem_altmap *altmap = NULL;
+ struct memory_block *mem;
+ u64 cur_start;
+ int rc;
+
+ /*
+ * For memmap_on_memory, the altmaps could have been added on
+ * a per-memblock basis. Loop through the entire range if so,
+ * and remove each memblock and its altmap.
+ */
+ for (cur_start = start; cur_start < start + size;
+ cur_start += memblock_size) {
+ rc = walk_memory_blocks(cur_start, memblock_size, &mem,
+ test_has_altmap_cb);
+ if (rc) {
+ altmap = mem->altmap;
+ /*
+ * Mark altmap NULL so that we can add a debug
+ * check on memblock free.
+ */
+ mem->altmap = NULL;
+ }
+
+ remove_memory_block_devices(cur_start, memblock_size);
+
+ arch_remove_memory(cur_start, memblock_size, altmap);
+
+ /* Verify that all vmemmap pages have actually been freed. */
+ if (altmap) {
+ WARN(altmap->alloc, "Altmap not fully unmapped");
+ kfree(altmap);
+ }
+ }
+}
+
+static int memory_blocks_have_altmaps(u64 start, u64 size)
+{
+ u64 num_memblocks = size / memory_block_size_bytes();
+ u64 num_altmaps = 0;
+
+ if (!mhp_memmap_on_memory())
+ return 0;
+
+ walk_memory_blocks(start, size, &num_altmaps,
+ count_memory_range_altmaps_cb);
+
+ if (num_altmaps == 0)
+ return 0;
+
+ if (num_memblocks != num_altmaps) {
+ WARN_ONCE(1, "Not all memblocks in range have altmaps");
+ return -EINVAL;
+ }
+
+ return 1;
+}
+
+static int __ref try_remove_memory(u64 start, u64 size)
+{
+ int rc, nid = NUMA_NO_NODE;
BUG_ON(check_hotplug_memory_range(start, size));
@@ -2167,45 +2265,25 @@ static int __ref try_remove_memory(u64 start, u64 size)
if (rc)
return rc;
- /*
- * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in
- * the same granularity it was added - a single memory block.
- */
- if (mhp_memmap_on_memory()) {
- rc = walk_memory_blocks(start, size, &mem, test_has_altmap_cb);
- if (rc) {
- if (size != memory_block_size_bytes()) {
- pr_warn("Refuse to remove %#llx - %#llx,"
- "wrong granularity\n",
- start, start + size);
- return -EINVAL;
- }
- altmap = mem->altmap;
- /*
- * Mark altmap NULL so that we can add a debug
- * check on memblock free.
- */
- mem->altmap = NULL;
- }
- }
-
/* remove memmap entry */
firmware_map_remove(start, start + size, "System RAM");
- /*
- * Memory block device removal under the device_hotplug_lock is
- * a barrier against racing online attempts.
- */
- remove_memory_block_devices(start, size);
-
mem_hotplug_begin();
- arch_remove_memory(start, size, altmap);
-
- /* Verify that all vmemmap pages have actually been freed. */
- if (altmap) {
- WARN(altmap->alloc, "Altmap not fully unmapped");
- kfree(altmap);
+ rc = memory_blocks_have_altmaps(start, size);
+ if (rc < 0) {
+ goto err;
+ } else if (rc == 0) {
+ /*
+ * Memory block device removal under the device_hotplug_lock is
+ * a barrier against racing online attempts.
+ * No altmaps present, do the removal directly
+ */
+ remove_memory_block_devices(start, size);
+ arch_remove_memory(start, size, NULL);
+ } else {
+ /* all memblocks in the range have altmaps */
+ remove_memory_blocks_and_altmaps(start, size);
}
if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
@@ -2218,8 +2296,9 @@ static int __ref try_remove_memory(u64 start, u64 size)
if (nid != NUMA_NO_NODE)
try_offline_node(nid);
+err:
mem_hotplug_done();
- return 0;
+ return (rc < 0 ? rc : 0);
}
/**
--
2.41.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v7 3/3] dax/kmem: allow kmem to add memory with memmap_on_memory
2023-10-25 22:44 [PATCH v7 0/3] mm: use memmap_on_memory semantics for dax/kmem Vishal Verma
2023-10-25 22:44 ` [PATCH v7 1/3] mm/memory_hotplug: replace an open-coded kmemdup() in add_memory_resource() Vishal Verma
2023-10-25 22:44 ` [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks Vishal Verma
@ 2023-10-25 22:44 ` Vishal Verma
2023-10-30 2:57 ` Huang, Ying
2 siblings, 1 reply; 9+ messages in thread
From: Vishal Verma @ 2023-10-25 22:44 UTC (permalink / raw
To: Andrew Morton, David Hildenbrand, Oscar Salvador, Dan Williams,
Dave Jiang
Cc: linux-kernel, linux-mm, nvdimm, linux-cxl, Huang Ying,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer, Vishal Verma, Jonathan Cameron
Large amounts of memory managed by the kmem driver may come in via CXL,
and it is often desirable to have the memmap for this memory on the new
memory itself.
Enroll kmem-managed memory for memmap_on_memory semantics if the dax
region originates via CXL. For non-CXL dax regions, retain the existing
default behavior of hot adding without memmap_on_memory semantics.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---
drivers/dax/bus.h | 1 +
drivers/dax/dax-private.h | 1 +
drivers/dax/bus.c | 3 +++
drivers/dax/cxl.c | 1 +
drivers/dax/hmem/hmem.c | 1 +
drivers/dax/kmem.c | 8 +++++++-
drivers/dax/pmem.c | 1 +
7 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
index 1ccd23360124..cbbf64443098 100644
--- a/drivers/dax/bus.h
+++ b/drivers/dax/bus.h
@@ -23,6 +23,7 @@ struct dev_dax_data {
struct dev_pagemap *pgmap;
resource_size_t size;
int id;
+ bool memmap_on_memory;
};
struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);
diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
index 27cf2daaaa79..446617b73aea 100644
--- a/drivers/dax/dax-private.h
+++ b/drivers/dax/dax-private.h
@@ -70,6 +70,7 @@ struct dev_dax {
struct ida ida;
struct device dev;
struct dev_pagemap *pgmap;
+ bool memmap_on_memory;
int nr_range;
struct dev_dax_range {
unsigned long pgoff;
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 0ee96e6fc426..ad9f821b8c78 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -367,6 +367,7 @@ static ssize_t create_store(struct device *dev, struct device_attribute *attr,
.dax_region = dax_region,
.size = 0,
.id = -1,
+ .memmap_on_memory = false,
};
struct dev_dax *dev_dax = devm_create_dev_dax(&data);
@@ -1400,6 +1401,8 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
dev_dax->align = dax_region->align;
ida_init(&dev_dax->ida);
+ dev_dax->memmap_on_memory = data->memmap_on_memory;
+
inode = dax_inode(dax_dev);
dev->devt = inode->i_rdev;
dev->bus = &dax_bus_type;
diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
index 8bc9d04034d6..c696837ab23c 100644
--- a/drivers/dax/cxl.c
+++ b/drivers/dax/cxl.c
@@ -26,6 +26,7 @@ static int cxl_dax_region_probe(struct device *dev)
.dax_region = dax_region,
.id = -1,
.size = range_len(&cxlr_dax->hpa_range),
+ .memmap_on_memory = true,
};
return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
index 5d2ddef0f8f5..b9da69f92697 100644
--- a/drivers/dax/hmem/hmem.c
+++ b/drivers/dax/hmem/hmem.c
@@ -36,6 +36,7 @@ static int dax_hmem_probe(struct platform_device *pdev)
.dax_region = dax_region,
.id = -1,
.size = region_idle ? 0 : range_len(&mri->range),
+ .memmap_on_memory = false,
};
return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index c57acb73e3db..0aa6c45a4e5a 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -12,6 +12,7 @@
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/memory-tiers.h>
+#include <linux/memory_hotplug.h>
#include "dax-private.h"
#include "bus.h"
@@ -56,6 +57,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
unsigned long total_len = 0;
struct dax_kmem_data *data;
int i, rc, mapped = 0;
+ mhp_t mhp_flags;
int numa_node;
/*
@@ -136,12 +138,16 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
*/
res->flags = IORESOURCE_SYSTEM_RAM;
+ mhp_flags = MHP_NID_IS_MGID;
+ if (dev_dax->memmap_on_memory)
+ mhp_flags |= MHP_MEMMAP_ON_MEMORY;
+
/*
* Ensure that future kexec'd kernels will not treat
* this as RAM automatically.
*/
rc = add_memory_driver_managed(data->mgid, range.start,
- range_len(&range), kmem_name, MHP_NID_IS_MGID);
+ range_len(&range), kmem_name, mhp_flags);
if (rc) {
dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index ae0cb113a5d3..f3c6c67b8412 100644
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -63,6 +63,7 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
.id = id,
.pgmap = &pgmap,
.size = range_len(&range),
+ .memmap_on_memory = false,
};
return devm_create_dev_dax(&data);
--
2.41.0
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks
2023-10-25 22:44 ` [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks Vishal Verma
@ 2023-10-30 2:46 ` Huang, Ying
2023-10-30 10:20 ` David Hildenbrand
1 sibling, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2023-10-30 2:46 UTC (permalink / raw
To: Vishal Verma
Cc: Andrew Morton, David Hildenbrand, Oscar Salvador, Dan Williams,
Dave Jiang, linux-kernel, linux-mm, nvdimm, linux-cxl,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer
Vishal Verma <vishal.l.verma@intel.com> writes:
> The MHP_MEMMAP_ON_MEMORY flag for hotplugged memory is restricted to
> 'memblock_size' chunks of memory being added. Adding a larger span of
> memory precludes memmap_on_memory semantics.
>
> For users of hotplug such as kmem, large amounts of memory might get
> added from the CXL subsystem. In some cases, this amount may exceed the
> available 'main memory' to store the memmap for the memory being added.
> In this case, it is useful to have a way to place the memmap on the
> memory being added, even if it means splitting the addition into
> memblock-sized chunks.
>
> Change add_memory_resource() to loop over memblock-sized chunks of
> memory if caller requested memmap_on_memory, and if other conditions for
> it are met. Teach try_remove_memory() to also expect that a memory
> range being removed might have been split up into memblock sized chunks,
> and to loop through those as needed.
>
> This does preclude being able to use PUD mappings in the direct map; a
> proposal to how this could be optimized in the future is laid out
> here[1].
>
> [1]: https://lore.kernel.org/linux-mm/b6753402-2de9-25b2-36e9-eacd49752b19@redhat.com/
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Suggested-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
> mm/memory_hotplug.c | 209 ++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 144 insertions(+), 65 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 6be7de9efa55..b97035193090 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1380,6 +1380,48 @@ static bool mhp_supports_memmap_on_memory(unsigned long size)
> return arch_supports_memmap_on_memory(vmemmap_size);
> }
>
> +static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group,
> + u64 start, u64 size)
> +{
> + unsigned long memblock_size = memory_block_size_bytes();
> + u64 cur_start;
> + int ret;
> +
> + for (cur_start = start; cur_start < start + size;
> + cur_start += memblock_size) {
> + struct mhp_params params = { .pgprot =
> + pgprot_mhp(PAGE_KERNEL) };
> + struct vmem_altmap mhp_altmap = {
> + .base_pfn = PHYS_PFN(cur_start),
> + .end_pfn = PHYS_PFN(cur_start + memblock_size - 1),
> + };
> +
> + mhp_altmap.free = memory_block_memmap_on_memory_pages();
> + params.altmap = kmemdup(&mhp_altmap, sizeof(struct vmem_altmap),
> + GFP_KERNEL);
> + if (!params.altmap)
> + return -ENOMEM;
> +
> + /* call arch's memory hotadd */
> + ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms);
> + if (ret < 0) {
> + kfree(params.altmap);
Should we call
remove_memory_blocks_and_altmaps(start, cur_start - start);
here to clean up resources?
--
Best Regards,
Huang, Ying
> + return ret;
> + }
> +
> + /* create memory block devices after memory was added */
> + ret = create_memory_block_devices(cur_start, memblock_size,
> + params.altmap, group);
> + if (ret) {
> + arch_remove_memory(cur_start, memblock_size, NULL);
> + kfree(params.altmap);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> /*
> * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
> * and online/offline operations (triggered e.g. by sysfs).
> @@ -1390,10 +1432,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
> {
> struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
> enum memblock_flags memblock_flags = MEMBLOCK_NONE;
> - struct vmem_altmap mhp_altmap = {
> - .base_pfn = PHYS_PFN(res->start),
> - .end_pfn = PHYS_PFN(res->end),
> - };
> struct memory_group *group = NULL;
> u64 start, size;
> bool new_node = false;
> @@ -1436,28 +1474,22 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
> /*
> * Self hosted memmap array
> */
> - if (mhp_flags & MHP_MEMMAP_ON_MEMORY) {
> - if (mhp_supports_memmap_on_memory(size)) {
> - mhp_altmap.free = memory_block_memmap_on_memory_pages();
> - params.altmap = kmemdup(&mhp_altmap,
> - sizeof(struct vmem_altmap),
> - GFP_KERNEL);
> - if (!params.altmap)
> - goto error;
> + if ((mhp_flags & MHP_MEMMAP_ON_MEMORY) &&
> + mhp_supports_memmap_on_memory(memory_block_size_bytes())) {
> + ret = create_altmaps_and_memory_blocks(nid, group, start, size);
> + if (ret)
> + goto error;
> + } else {
> + ret = arch_add_memory(nid, start, size, ¶ms);
> + if (ret < 0)
> + goto error;
> +
> + /* create memory block devices after memory was added */
> + ret = create_memory_block_devices(start, size, NULL, group);
> + if (ret) {
> + arch_remove_memory(start, size, NULL);
> + goto error;
> }
> - /* fallback to not using altmap */
> - }
> -
> - /* call arch's memory hotadd */
> - ret = arch_add_memory(nid, start, size, ¶ms);
> - if (ret < 0)
> - goto error_free;
> -
> - /* create memory block devices after memory was added */
> - ret = create_memory_block_devices(start, size, params.altmap, group);
> - if (ret) {
> - arch_remove_memory(start, size, NULL);
> - goto error_free;
> }
>
> if (new_node) {
> @@ -1494,8 +1526,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
> walk_memory_blocks(start, size, NULL, online_memory_block);
>
> return ret;
> -error_free:
> - kfree(params.altmap);
> error:
> if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
> memblock_remove(start, size);
> @@ -2076,6 +2106,16 @@ static int test_has_altmap_cb(struct memory_block *mem, void *arg)
> return 0;
> }
>
> +static int count_memory_range_altmaps_cb(struct memory_block *mem, void *arg)
> +{
> + u64 *num_altmaps = (u64 *)arg;
> +
> + if (mem->altmap)
> + *num_altmaps += 1;
> +
> + return 0;
> +}
> +
> static int check_cpu_on_node(int nid)
> {
> int cpu;
> @@ -2146,11 +2186,69 @@ void try_offline_node(int nid)
> }
> EXPORT_SYMBOL(try_offline_node);
>
> -static int __ref try_remove_memory(u64 start, u64 size)
> +static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size)
> {
> - struct memory_block *mem;
> - int rc = 0, nid = NUMA_NO_NODE;
> + unsigned long memblock_size = memory_block_size_bytes();
> struct vmem_altmap *altmap = NULL;
> + struct memory_block *mem;
> + u64 cur_start;
> + int rc;
> +
> + /*
> + * For memmap_on_memory, the altmaps could have been added on
> + * a per-memblock basis. Loop through the entire range if so,
> + * and remove each memblock and its altmap.
> + */
> + for (cur_start = start; cur_start < start + size;
> + cur_start += memblock_size) {
> + rc = walk_memory_blocks(cur_start, memblock_size, &mem,
> + test_has_altmap_cb);
> + if (rc) {
> + altmap = mem->altmap;
> + /*
> + * Mark altmap NULL so that we can add a debug
> + * check on memblock free.
> + */
> + mem->altmap = NULL;
> + }
> +
> + remove_memory_block_devices(cur_start, memblock_size);
> +
> + arch_remove_memory(cur_start, memblock_size, altmap);
> +
> + /* Verify that all vmemmap pages have actually been freed. */
> + if (altmap) {
> + WARN(altmap->alloc, "Altmap not fully unmapped");
> + kfree(altmap);
> + }
> + }
> +}
> +
> +static int memory_blocks_have_altmaps(u64 start, u64 size)
> +{
> + u64 num_memblocks = size / memory_block_size_bytes();
> + u64 num_altmaps = 0;
> +
> + if (!mhp_memmap_on_memory())
> + return 0;
> +
> + walk_memory_blocks(start, size, &num_altmaps,
> + count_memory_range_altmaps_cb);
> +
> + if (num_altmaps == 0)
> + return 0;
> +
> + if (num_memblocks != num_altmaps) {
> + WARN_ONCE(1, "Not all memblocks in range have altmaps");
> + return -EINVAL;
> + }
> +
> + return 1;
> +}
> +
> +static int __ref try_remove_memory(u64 start, u64 size)
> +{
> + int rc, nid = NUMA_NO_NODE;
>
> BUG_ON(check_hotplug_memory_range(start, size));
>
> @@ -2167,45 +2265,25 @@ static int __ref try_remove_memory(u64 start, u64 size)
> if (rc)
> return rc;
>
> - /*
> - * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in
> - * the same granularity it was added - a single memory block.
> - */
> - if (mhp_memmap_on_memory()) {
> - rc = walk_memory_blocks(start, size, &mem, test_has_altmap_cb);
> - if (rc) {
> - if (size != memory_block_size_bytes()) {
> - pr_warn("Refuse to remove %#llx - %#llx,"
> - "wrong granularity\n",
> - start, start + size);
> - return -EINVAL;
> - }
> - altmap = mem->altmap;
> - /*
> - * Mark altmap NULL so that we can add a debug
> - * check on memblock free.
> - */
> - mem->altmap = NULL;
> - }
> - }
> -
> /* remove memmap entry */
> firmware_map_remove(start, start + size, "System RAM");
>
> - /*
> - * Memory block device removal under the device_hotplug_lock is
> - * a barrier against racing online attempts.
> - */
> - remove_memory_block_devices(start, size);
> -
> mem_hotplug_begin();
>
> - arch_remove_memory(start, size, altmap);
> -
> - /* Verify that all vmemmap pages have actually been freed. */
> - if (altmap) {
> - WARN(altmap->alloc, "Altmap not fully unmapped");
> - kfree(altmap);
> + rc = memory_blocks_have_altmaps(start, size);
> + if (rc < 0) {
> + goto err;
> + } else if (rc == 0) {
> + /*
> + * Memory block device removal under the device_hotplug_lock is
> + * a barrier against racing online attempts.
> + * No altmaps present, do the removal directly
> + */
> + remove_memory_block_devices(start, size);
> + arch_remove_memory(start, size, NULL);
> + } else {
> + /* all memblocks in the range have altmaps */
> + remove_memory_blocks_and_altmaps(start, size);
> }
>
> if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
> @@ -2218,8 +2296,9 @@ static int __ref try_remove_memory(u64 start, u64 size)
> if (nid != NUMA_NO_NODE)
> try_offline_node(nid);
>
> +err:
> mem_hotplug_done();
> - return 0;
> + return (rc < 0 ? rc : 0);
> }
>
> /**
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v7 3/3] dax/kmem: allow kmem to add memory with memmap_on_memory
2023-10-25 22:44 ` [PATCH v7 3/3] dax/kmem: allow kmem to add memory with memmap_on_memory Vishal Verma
@ 2023-10-30 2:57 ` Huang, Ying
0 siblings, 0 replies; 9+ messages in thread
From: Huang, Ying @ 2023-10-30 2:57 UTC (permalink / raw
To: Vishal Verma
Cc: Andrew Morton, David Hildenbrand, Oscar Salvador, Dan Williams,
Dave Jiang, linux-kernel, linux-mm, nvdimm, linux-cxl,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer
Vishal Verma <vishal.l.verma@intel.com> writes:
> Large amounts of memory managed by the kmem driver may come in via CXL,
> and it is often desirable to have the memmap for this memory on the new
> memory itself.
>
> Enroll kmem-managed memory for memmap_on_memory semantics if the dax
> region originates via CXL. For non-CXL dax regions, retain the existing
> default behavior of hot adding without memmap_on_memory semantics.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Oscar Salvador <osalvador@suse.de>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Dave Jiang <dave.jiang@intel.com>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Huang Ying <ying.huang@intel.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
LGTM, Thanks!
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
> ---
> drivers/dax/bus.h | 1 +
> drivers/dax/dax-private.h | 1 +
> drivers/dax/bus.c | 3 +++
> drivers/dax/cxl.c | 1 +
> drivers/dax/hmem/hmem.c | 1 +
> drivers/dax/kmem.c | 8 +++++++-
> drivers/dax/pmem.c | 1 +
> 7 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
> index 1ccd23360124..cbbf64443098 100644
> --- a/drivers/dax/bus.h
> +++ b/drivers/dax/bus.h
> @@ -23,6 +23,7 @@ struct dev_dax_data {
> struct dev_pagemap *pgmap;
> resource_size_t size;
> int id;
> + bool memmap_on_memory;
> };
>
> struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data);
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index 27cf2daaaa79..446617b73aea 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -70,6 +70,7 @@ struct dev_dax {
> struct ida ida;
> struct device dev;
> struct dev_pagemap *pgmap;
> + bool memmap_on_memory;
> int nr_range;
> struct dev_dax_range {
> unsigned long pgoff;
> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
> index 0ee96e6fc426..ad9f821b8c78 100644
> --- a/drivers/dax/bus.c
> +++ b/drivers/dax/bus.c
> @@ -367,6 +367,7 @@ static ssize_t create_store(struct device *dev, struct device_attribute *attr,
> .dax_region = dax_region,
> .size = 0,
> .id = -1,
> + .memmap_on_memory = false,
> };
> struct dev_dax *dev_dax = devm_create_dev_dax(&data);
>
> @@ -1400,6 +1401,8 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
> dev_dax->align = dax_region->align;
> ida_init(&dev_dax->ida);
>
> + dev_dax->memmap_on_memory = data->memmap_on_memory;
> +
> inode = dax_inode(dax_dev);
> dev->devt = inode->i_rdev;
> dev->bus = &dax_bus_type;
> diff --git a/drivers/dax/cxl.c b/drivers/dax/cxl.c
> index 8bc9d04034d6..c696837ab23c 100644
> --- a/drivers/dax/cxl.c
> +++ b/drivers/dax/cxl.c
> @@ -26,6 +26,7 @@ static int cxl_dax_region_probe(struct device *dev)
> .dax_region = dax_region,
> .id = -1,
> .size = range_len(&cxlr_dax->hpa_range),
> + .memmap_on_memory = true,
> };
>
> return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
> diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
> index 5d2ddef0f8f5..b9da69f92697 100644
> --- a/drivers/dax/hmem/hmem.c
> +++ b/drivers/dax/hmem/hmem.c
> @@ -36,6 +36,7 @@ static int dax_hmem_probe(struct platform_device *pdev)
> .dax_region = dax_region,
> .id = -1,
> .size = region_idle ? 0 : range_len(&mri->range),
> + .memmap_on_memory = false,
> };
>
> return PTR_ERR_OR_ZERO(devm_create_dev_dax(&data));
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index c57acb73e3db..0aa6c45a4e5a 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -12,6 +12,7 @@
> #include <linux/mm.h>
> #include <linux/mman.h>
> #include <linux/memory-tiers.h>
> +#include <linux/memory_hotplug.h>
> #include "dax-private.h"
> #include "bus.h"
>
> @@ -56,6 +57,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> unsigned long total_len = 0;
> struct dax_kmem_data *data;
> int i, rc, mapped = 0;
> + mhp_t mhp_flags;
> int numa_node;
>
> /*
> @@ -136,12 +138,16 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> */
> res->flags = IORESOURCE_SYSTEM_RAM;
>
> + mhp_flags = MHP_NID_IS_MGID;
> + if (dev_dax->memmap_on_memory)
> + mhp_flags |= MHP_MEMMAP_ON_MEMORY;
> +
> /*
> * Ensure that future kexec'd kernels will not treat
> * this as RAM automatically.
> */
> rc = add_memory_driver_managed(data->mgid, range.start,
> - range_len(&range), kmem_name, MHP_NID_IS_MGID);
> + range_len(&range), kmem_name, mhp_flags);
>
> if (rc) {
> dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
> diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
> index ae0cb113a5d3..f3c6c67b8412 100644
> --- a/drivers/dax/pmem.c
> +++ b/drivers/dax/pmem.c
> @@ -63,6 +63,7 @@ static struct dev_dax *__dax_pmem_probe(struct device *dev)
> .id = id,
> .pgmap = &pgmap,
> .size = range_len(&range),
> + .memmap_on_memory = false,
> };
>
> return devm_create_dev_dax(&data);
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks
2023-10-25 22:44 ` [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks Vishal Verma
2023-10-30 2:46 ` Huang, Ying
@ 2023-10-30 10:20 ` David Hildenbrand
2023-10-31 2:14 ` Verma, Vishal L
1 sibling, 1 reply; 9+ messages in thread
From: David Hildenbrand @ 2023-10-30 10:20 UTC (permalink / raw
To: Vishal Verma, Andrew Morton, Oscar Salvador, Dan Williams,
Dave Jiang
Cc: linux-kernel, linux-mm, nvdimm, linux-cxl, Huang Ying,
Dave Hansen, Aneesh Kumar K.V, Michal Hocko, Jonathan Cameron,
Jeff Moyer
On 26.10.23 00:44, Vishal Verma wrote:
> The MHP_MEMMAP_ON_MEMORY flag for hotplugged memory is restricted to
> 'memblock_size' chunks of memory being added. Adding a larger span of
> memory precludes memmap_on_memory semantics.
>
> For users of hotplug such as kmem, large amounts of memory might get
> added from the CXL subsystem. In some cases, this amount may exceed the
> available 'main memory' to store the memmap for the memory being added.
> In this case, it is useful to have a way to place the memmap on the
> memory being added, even if it means splitting the addition into
> memblock-sized chunks.
>
> Change add_memory_resource() to loop over memblock-sized chunks of
> memory if caller requested memmap_on_memory, and if other conditions for
> it are met. Teach try_remove_memory() to also expect that a memory
> range being removed might have been split up into memblock sized chunks,
> and to loop through those as needed.
>
> This does preclude being able to use PUD mappings in the direct map; a
> proposal to how this could be optimized in the future is laid out
> here[1].
Almost there, I think :)
>
> +static int create_altmaps_and_memory_blocks(int nid, struct memory_group *group,
> + u64 start, u64 size)
> +{
> + unsigned long memblock_size = memory_block_size_bytes();
> + u64 cur_start;
> + int ret;
> +
> + for (cur_start = start; cur_start < start + size;
> + cur_start += memblock_size) {
> + struct mhp_params params = { .pgprot =
> + pgprot_mhp(PAGE_KERNEL) };
> + struct vmem_altmap mhp_altmap = {
> + .base_pfn = PHYS_PFN(cur_start),
> + .end_pfn = PHYS_PFN(cur_start + memblock_size - 1),
> + };
> +
> + mhp_altmap.free = memory_block_memmap_on_memory_pages();
> + params.altmap = kmemdup(&mhp_altmap, sizeof(struct vmem_altmap),
> + GFP_KERNEL);
> + if (!params.altmap)
> + return -ENOMEM;
Best to cleanup here instead of handling it in the caller [as noted by
Vishal, we might not be doing that yet]. Using
remove_memory_blocks_and_altmaps() on the fully processed range sounds
reasonable.
maybe something like
ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms);
if (ret) {
kfree(params.altmap);
goto out;
}
ret = create_memory_block_devices(cur_start, memblock_size,
params.altmap, group);
if (ret) {
arch_remove_memory(cur_start, memblock_size, NULL);
kfree(params.altmap);
goto out;
}
if (ret && cur_start != start)
remove_memory_blocks_and_altmaps(start, cur_start - start);
return ret;
> +
> + /* call arch's memory hotadd */
> + ret = arch_add_memory(nid, cur_start, memblock_size, ¶ms);
> + if (ret < 0) {
> + kfree(params.altmap);
> + return ret;
> + }
> +
> + /* create memory block devices after memory was added */
> + ret = create_memory_block_devices(cur_start, memblock_size,
> + params.altmap, group);
> + if (ret) {
> + arch_remove_memory(cur_start, memblock_size, NULL);
> + kfree(params.altmap);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
[...]
> static int check_cpu_on_node(int nid)
> {
> int cpu;
> @@ -2146,11 +2186,69 @@ void try_offline_node(int nid)
> }
> EXPORT_SYMBOL(try_offline_node);
>
> -static int __ref try_remove_memory(u64 start, u64 size)
> +static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size)
> {
> - struct memory_block *mem;
> - int rc = 0, nid = NUMA_NO_NODE;
> + unsigned long memblock_size = memory_block_size_bytes();
> struct vmem_altmap *altmap = NULL;
> + struct memory_block *mem;
> + u64 cur_start;
> + int rc;
> +
> + /*
> + * For memmap_on_memory, the altmaps could have been added on
> + * a per-memblock basis. Loop through the entire range if so,
> + * and remove each memblock and its altmap.
> + */
/*
* altmaps where added on a per-memblock basis; we have to process
* each individual memory block.
*/
> + for (cur_start = start; cur_start < start + size;
> + cur_start += memblock_size) {
> + rc = walk_memory_blocks(cur_start, memblock_size, &mem,
> + test_has_altmap_cb);
> + if (rc) {
> + altmap = mem->altmap;
> + /*
> + * Mark altmap NULL so that we can add a debug
> + * check on memblock free.
> + */
> + mem->altmap = NULL;
> + }
Simpler (especially, we know that there must be an altmap):
mem = find_memory_block(pfn_to_section_nr(cur_start));
altmap = mem->altmap;
mem->altmap = NULL;
I think we might be able to remove test_has_altmap_cb() then.
> +
> + remove_memory_block_devices(cur_start, memblock_size);
> +
> + arch_remove_memory(cur_start, memblock_size, altmap);
> +
> + /* Verify that all vmemmap pages have actually been freed. */
> + if (altmap) {
There must be an altmap, so this can be done unconditionally.
> + WARN(altmap->alloc, "Altmap not fully unmapped");
> + kfree(altmap);
> + }
> + }
> +}
--
Cheers,
David / dhildenb
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks
2023-10-30 10:20 ` David Hildenbrand
@ 2023-10-31 2:14 ` Verma, Vishal L
2023-10-31 10:13 ` David Hildenbrand
0 siblings, 1 reply; 9+ messages in thread
From: Verma, Vishal L @ 2023-10-31 2:14 UTC (permalink / raw
To: Williams, Dan J, Jiang, Dave, osalvador@suse.de, david@redhat.com,
akpm@linux-foundation.org
Cc: dave.hansen@linux.intel.com, Huang, Ying, linux-mm@kvack.org,
aneesh.kumar@linux.ibm.com, linux-kernel@vger.kernel.org,
linux-cxl@vger.kernel.org, Hocko, Michal, nvdimm@lists.linux.dev,
jmoyer@redhat.com, Jonathan.Cameron@Huawei.com
On Mon, 2023-10-30 at 11:20 +0100, David Hildenbrand wrote:
> On 26.10.23 00:44, Vishal Verma wrote:
> >
[..]
> > @@ -2146,11 +2186,69 @@ void try_offline_node(int nid)
> > }
> > EXPORT_SYMBOL(try_offline_node);
> >
> > -static int __ref try_remove_memory(u64 start, u64 size)
> > +static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size)
> > {
> > - struct memory_block *mem;
> > - int rc = 0, nid = NUMA_NO_NODE;
> > + unsigned long memblock_size = memory_block_size_bytes();
> > struct vmem_altmap *altmap = NULL;
> > + struct memory_block *mem;
> > + u64 cur_start;
> > + int rc;
> > +
> > + /*
> > + * For memmap_on_memory, the altmaps could have been added on
> > + * a per-memblock basis. Loop through the entire range if so,
> > + * and remove each memblock and its altmap.
> > + */
>
> /*
> * altmaps where added on a per-memblock basis; we have to process
> * each individual memory block.
> */
>
> > + for (cur_start = start; cur_start < start + size;
> > + cur_start += memblock_size) {
> > + rc = walk_memory_blocks(cur_start, memblock_size, &mem,
> > + test_has_altmap_cb);
> > + if (rc) {
> > + altmap = mem->altmap;
> > + /*
> > + * Mark altmap NULL so that we can add a debug
> > + * check on memblock free.
> > + */
> > + mem->altmap = NULL;
> > + }
>
> Simpler (especially, we know that there must be an altmap):
>
> mem = find_memory_block(pfn_to_section_nr(cur_start));
> altmap = mem->altmap;
> mem->altmap = NULL;
>
> I think we might be able to remove test_has_altmap_cb() then.
>
> > +
> > + remove_memory_block_devices(cur_start, memblock_size);
> > +
> > + arch_remove_memory(cur_start, memblock_size, altmap);
> > +
> > + /* Verify that all vmemmap pages have actually been freed. */
> > + if (altmap) {
>
> There must be an altmap, so this can be done unconditionally.
Hi David,
All other comments make sense, making those changes now.
However for this one, does the WARN() below go away then?
I was wondering if maybe arch_remove_memory() is responsible for
freeing the altmap here, and at this stage we're just checking if that
happened. If it didn't WARN and then free it.
I drilled down the path, and I don't see altmap actually getting freed
in vmem_altmap_free(), but I wasn't sure if <something else> was meant
to free it as altmap->alloc went down to 0.
>
> > + WARN(altmap->alloc, "Altmap not fully unmapped");
> > + kfree(altmap);
> > + }
> > + }
> > +}
>
>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks
2023-10-31 2:14 ` Verma, Vishal L
@ 2023-10-31 10:13 ` David Hildenbrand
0 siblings, 0 replies; 9+ messages in thread
From: David Hildenbrand @ 2023-10-31 10:13 UTC (permalink / raw
To: Verma, Vishal L, Williams, Dan J, Jiang, Dave, osalvador@suse.de,
akpm@linux-foundation.org
Cc: dave.hansen@linux.intel.com, Huang, Ying, linux-mm@kvack.org,
aneesh.kumar@linux.ibm.com, linux-kernel@vger.kernel.org,
linux-cxl@vger.kernel.org, Hocko, Michal, nvdimm@lists.linux.dev,
jmoyer@redhat.com, Jonathan.Cameron@Huawei.com
On 31.10.23 03:14, Verma, Vishal L wrote:
> On Mon, 2023-10-30 at 11:20 +0100, David Hildenbrand wrote:
>> On 26.10.23 00:44, Vishal Verma wrote:
>>>
> [..]
>
>>> @@ -2146,11 +2186,69 @@ void try_offline_node(int nid)
>>> }
>>> EXPORT_SYMBOL(try_offline_node);
>>>
>>> -static int __ref try_remove_memory(u64 start, u64 size)
>>> +static void __ref remove_memory_blocks_and_altmaps(u64 start, u64 size)
>>> {
>>> - struct memory_block *mem;
>>> - int rc = 0, nid = NUMA_NO_NODE;
>>> + unsigned long memblock_size = memory_block_size_bytes();
>>> struct vmem_altmap *altmap = NULL;
>>> + struct memory_block *mem;
>>> + u64 cur_start;
>>> + int rc;
>>> +
>>> + /*
>>> + * For memmap_on_memory, the altmaps could have been added on
>>> + * a per-memblock basis. Loop through the entire range if so,
>>> + * and remove each memblock and its altmap.
>>> + */
>>
>> /*
>> * altmaps where added on a per-memblock basis; we have to process
>> * each individual memory block.
>> */
>>
>>> + for (cur_start = start; cur_start < start + size;
>>> + cur_start += memblock_size) {
>>> + rc = walk_memory_blocks(cur_start, memblock_size, &mem,
>>> + test_has_altmap_cb);
>>> + if (rc) {
>>> + altmap = mem->altmap;
>>> + /*
>>> + * Mark altmap NULL so that we can add a debug
>>> + * check on memblock free.
>>> + */
>>> + mem->altmap = NULL;
>>> + }
>>
>> Simpler (especially, we know that there must be an altmap):
>>
>> mem = find_memory_block(pfn_to_section_nr(cur_start));
>> altmap = mem->altmap;
>> mem->altmap = NULL;
>>
>> I think we might be able to remove test_has_altmap_cb() then.
>>
>>> +
>>> + remove_memory_block_devices(cur_start, memblock_size);
>>> +
>>> + arch_remove_memory(cur_start, memblock_size, altmap);
>>> +
>>> + /* Verify that all vmemmap pages have actually been freed. */
>>> + if (altmap) {
>>
>> There must be an altmap, so this can be done unconditionally.
>
> Hi David,
Hi!
>
> All other comments make sense, making those changes now.
>
> However for this one, does the WARN() below go away then?
>
> I was wondering if maybe arch_remove_memory() is responsible for
> freeing the altmap here, and at this stage we're just checking if that
> happened. If it didn't WARN and then free it.
I think that has to stay, to make sure arch_remove_memory() did the
right thing and we don't -- by BUG -- still have some altmap pages in
use after they should have been completely freed.
>
> I drilled down the path, and I don't see altmap actually getting freed
> in vmem_altmap_free(), but I wasn't sure if <something else> was meant
> to free it as altmap->alloc went down to 0.
vmem_altmap_free() does the "altmap->alloc -= nr_pfns", which is called
when arch_remove_memory() frees the vmemmap pages and detects that they
actually come from the altmap reserve and not from the buddy/earlyboot
allocator.
Freeing an altmap is just unaccounting it in the altmap structure; and
here we make sure that we are actually back down to 0 and don't have
some weird altmap freeing BUG in arch_remove_memory().
--
Cheers,
David / dhildenb
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2023-10-31 10:13 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-10-25 22:44 [PATCH v7 0/3] mm: use memmap_on_memory semantics for dax/kmem Vishal Verma
2023-10-25 22:44 ` [PATCH v7 1/3] mm/memory_hotplug: replace an open-coded kmemdup() in add_memory_resource() Vishal Verma
2023-10-25 22:44 ` [PATCH v7 2/3] mm/memory_hotplug: split memmap_on_memory requests across memblocks Vishal Verma
2023-10-30 2:46 ` Huang, Ying
2023-10-30 10:20 ` David Hildenbrand
2023-10-31 2:14 ` Verma, Vishal L
2023-10-31 10:13 ` David Hildenbrand
2023-10-25 22:44 ` [PATCH v7 3/3] dax/kmem: allow kmem to add memory with memmap_on_memory Vishal Verma
2023-10-30 2:57 ` Huang, Ying
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