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David Hildenbrand

2020-Sep-08 20:10 UTC

[PATCH v2 0/7] mm/memory_hotplug: selective merging of system ram resources

Some add_memory*() users add memory in small, contiguous memory blocks.
Examples include virtio-mem, hyper-v balloon, and the XEN balloon.

This can quickly result in a lot of memory resources, whereby the actual
resource boundaries are not of interest (e.g., it might be relevant for
DIMMs, exposed via /proc/iomem to user space). We really want to merge
added resources in this scenario where possible.

Resources are effectively stored in a list-based tree. Having a lot of
resources not only wastes memory, it also makes traversing that tree more
expensive, and makes /proc/iomem explode in size (e.g., requiring
kexec-tools to manually merge resources when creating a kdump header. The
current kexec-tools resource count limit does not allow for more than
~100GB of memory with a memory block size of 128MB on x86-64).

Let's allow to selectively merge system ram resources by specifying a
new flag for add_memory*(). Patch #5 contains a /proc/iomem example. Only
tested with virtio-mem.

v1 -> v2:
- I had another look at v1 after vacation and didn't like it - it felt like
  a hack. So I want forward and added a proper flag to add_memory*(), and
  introduce a clean (non-racy) way to mark System RAM resources mergeable.
- "kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED"
-- Clean that flag up, felt wrong in the PnP section
- "mm/memory_hotplug: prepare passing flags to add_memory() and
friends"
-- Previously sent in other context - decided to keep Wei's ack
- "mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System
   RAM resources"
-- Cleaner approach to get the job done by using proper flags and only
   merging the single, specified resource
- "virtio-mem: try to merge system ram resources"
  "xen/balloon: try to merge system ram resources"
  "hv_balloon: try to merge system ram resources"
-- Use the new flag MEMHP_MERGE_RESOURCE, much cleaner

RFC -> v1:
- Switch from rather generic "merge_child_mem_resources()" where a
resource
  name has to be specified to "merge_system_ram_resources().
- Smaller comment/documentation/patch description changes/fixes

David Hildenbrand (7):
  kernel/resource: make release_mem_region_adjustable() never fail
  kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED
  mm/memory_hotplug: prepare passing flags to add_memory() and friends
  mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System
    RAM resources
  virtio-mem: try to merge system ram resources
  xen/balloon: try to merge system ram resources
  hv_balloon: try to merge system ram resources

 arch/powerpc/platforms/powernv/memtrace.c     |   2 +-
 .../platforms/pseries/hotplug-memory.c        |   2 +-
 drivers/acpi/acpi_memhotplug.c                |   2 +-
 drivers/base/memory.c                         |   2 +-
 drivers/dax/kmem.c                            |   2 +-
 drivers/hv/hv_balloon.c                       |   2 +-
 drivers/s390/char/sclp_cmd.c                  |   2 +-
 drivers/virtio/virtio_mem.c                   |   3 +-
 drivers/xen/balloon.c                         |   2 +-
 include/linux/ioport.h                        |  12 +-
 include/linux/memory_hotplug.h                |  19 ++-
 kernel/kexec_file.c                           |   2 +-
 kernel/resource.c                             | 109 ++++++++++++++----
 mm/memory_hotplug.c                           |  48 +++-----
 14 files changed, 141 insertions(+), 68 deletions(-)

-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 1/7] kernel/resource: make release_mem_region_adjustable() never fail

Let's make sure splitting a resource on memory hotunplug will never fail.
This will become more relevant once we merge selected System RAM
resources - then, we'll trigger that case more often on memory hotunplug.

In general, this function is already unlikely to fail. When we remove
memory, we free up quite a lot of metadata (memmap, page tables, memory
block device, etc.). The only reason it could really fail would be when
injecting allocation errors.

All other error cases inside release_mem_region_adjustable() seem to be
sanity checks if the function would be abused in different context -
let's add WARN_ON_ONCE() in these cases so we can catch them.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Jason Gunthorpe <jgg at ziepe.ca>
Cc: Kees Cook <keescook at chromium.org>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 include/linux/ioport.h |  4 ++--
 kernel/resource.c      | 49 ++++++++++++++++++++++++------------------
 mm/memory_hotplug.c    | 22 +------------------
 3 files changed, 31 insertions(+), 44 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6c2b06fe8beb7..52a91f5fa1a36 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -248,8 +248,8 @@ extern struct resource * __request_region(struct resource *,
 extern void __release_region(struct resource *, resource_size_t,
 				resource_size_t);
 #ifdef CONFIG_MEMORY_HOTREMOVE
-extern int release_mem_region_adjustable(struct resource *, resource_size_t,
-				resource_size_t);
+extern void release_mem_region_adjustable(struct resource *, resource_size_t,
+					  resource_size_t);
 #endif
 
 /* Wrappers for managed devices */
diff --git a/kernel/resource.c b/kernel/resource.c
index f1175ce93a1d5..36b3552210120 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1258,21 +1258,28 @@ EXPORT_SYMBOL(__release_region);
  *   assumes that all children remain in the lower address entry for
  *   simplicity.  Enhance this logic when necessary.
  */
-int release_mem_region_adjustable(struct resource *parent,
-				  resource_size_t start, resource_size_t size)
+void release_mem_region_adjustable(struct resource *parent,
+				   resource_size_t start, resource_size_t size)
 {
+	struct resource *new_res = NULL;
+	bool alloc_nofail = false;
 	struct resource **p;
 	struct resource *res;
-	struct resource *new_res;
 	resource_size_t end;
-	int ret = -EINVAL;
 
 	end = start + size - 1;
-	if ((start < parent->start) || (end > parent->end))
-		return ret;
+	if (WARN_ON_ONCE((start < parent->start) || (end > parent->end)))
+		return;
 
-	/* The alloc_resource() result gets checked later */
-	new_res = alloc_resource(GFP_KERNEL);
+	/*
+	 * We free up quite a lot of memory on memory hotunplug (esp., memap),
+	 * just before releasing the region. This is highly unlikely to
+	 * fail - let's play save and make it never fail as the caller cannot
+	 * perform any error handling (e.g., trying to re-add memory will fail
+	 * similarly).
+	 */
+retry:
+	new_res = alloc_resource(GFP_KERNEL | alloc_nofail ? __GFP_NOFAIL : 0);
 
 	p = &parent->child;
 	write_lock(&resource_lock);
@@ -1298,7 +1305,6 @@ int release_mem_region_adjustable(struct resource *parent,
 		 * so if we are dealing with them, let us just back off here.
 		 */
 		if (!(res->flags & IORESOURCE_SYSRAM)) {
-			ret = 0;
 			break;
 		}
 
@@ -1315,20 +1321,23 @@ int release_mem_region_adjustable(struct resource
*parent,
 			/* free the whole entry */
 			*p = res->sibling;
 			free_resource(res);
-			ret = 0;
 		} else if (res->start == start && res->end != end) {
 			/* adjust the start */
-			ret = __adjust_resource(res, end + 1,
-						res->end - end);
+			WARN_ON_ONCE(__adjust_resource(res, end + 1,
+						       res->end - end));
 		} else if (res->start != start && res->end == end) {
 			/* adjust the end */
-			ret = __adjust_resource(res, res->start,
-						start - res->start);
+			WARN_ON_ONCE(__adjust_resource(res, res->start,
+						       start - res->start));
 		} else {
-			/* split into two entries */
+			/* split into two entries - we need a new resource */
 			if (!new_res) {
-				ret = -ENOMEM;
-				break;
+				new_res = alloc_resource(GFP_ATOMIC);
+				if (!new_res) {
+					alloc_nofail = true;
+					write_unlock(&resource_lock);
+					goto retry;
+				}
 			}
 			new_res->name = res->name;
 			new_res->start = end + 1;
@@ -1339,9 +1348,8 @@ int release_mem_region_adjustable(struct resource *parent,
 			new_res->sibling = res->sibling;
 			new_res->child = NULL;
 
-			ret = __adjust_resource(res, res->start,
-						start - res->start);
-			if (ret)
+			if (WARN_ON_ONCE(__adjust_resource(res, res->start,
+							   start - res->start)))
 				break;
 			res->sibling = new_res;
 			new_res = NULL;
@@ -1352,7 +1360,6 @@ int release_mem_region_adjustable(struct resource *parent,
 
 	write_unlock(&resource_lock);
 	free_resource(new_res);
-	return ret;
 }
 #endif	/* CONFIG_MEMORY_HOTREMOVE */
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index baded53b9ff92..4c47b68a9f4b5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1724,26 +1724,6 @@ void try_offline_node(int nid)
 }
 EXPORT_SYMBOL(try_offline_node);
 
-static void __release_memory_resource(resource_size_t start,
-				      resource_size_t size)
-{
-	int ret;
-
-	/*
-	 * When removing memory in the same granularity as it was added,
-	 * this function never fails. It might only fail if resources
-	 * have to be adjusted or split. We'll ignore the error, as
-	 * removing of memory cannot fail.
-	 */
-	ret = release_mem_region_adjustable(&iomem_resource, start, size);
-	if (ret) {
-		resource_size_t endres = start + size - 1;
-
-		pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
-			&start, &endres, ret);
-	}
-}
-
 static int __ref try_remove_memory(int nid, u64 start, u64 size)
 {
 	int rc = 0;
@@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64
size)
 		memblock_remove(start, size);
 	}
 
-	__release_memory_resource(start, size);
+	release_mem_region_adjustable(&iomem_resource, start, size);
 
 	try_offline_node(nid);
 
-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 2/7] kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED

IORESOURCE_MEM_DRIVER_MANAGED currently uses an unused PnP bit, which is
always set to 0 by hardware. This is far from beautiful (and confusing),
and the bit only applies to SYSRAM. So let's move it out of the
bus-specific (PnP) defined bits.

We'll add another SYSRAM specific bit soon. If we ever need more bits for
other purposes, we can steal some from "desc", or reshuffle/regroup
what we
have.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Jason Gunthorpe <jgg at ziepe.ca>
Cc: Kees Cook <keescook at chromium.org>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Cc: Eric Biederman <ebiederm at xmission.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: kexec at lists.infradead.org
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 include/linux/ioport.h | 4 +++-
 kernel/kexec_file.c    | 2 +-
 mm/memory_hotplug.c    | 4 ++--
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 52a91f5fa1a36..d7620d7c941a0 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -58,6 +58,9 @@ struct resource {
 #define IORESOURCE_EXT_TYPE_BITS 0x01000000	/* Resource extended types */
 #define IORESOURCE_SYSRAM	0x01000000	/* System RAM (modifier) */
 
+/* IORESOURCE_SYSRAM specific bits. */
+#define IORESOURCE_SYSRAM_DRIVER_MANAGED	0x02000000 /* Always detected via a
driver. */
+
 #define IORESOURCE_EXCLUSIVE	0x08000000	/* Userland may not map this resource
*/
 
 #define IORESOURCE_DISABLED	0x10000000
@@ -103,7 +106,6 @@ struct resource {
 #define IORESOURCE_MEM_32BIT		(3<<3)
 #define IORESOURCE_MEM_SHADOWABLE	(1<<5)	/* dup: IORESOURCE_SHADOWABLE */
 #define IORESOURCE_MEM_EXPANSIONROM	(1<<6)
-#define IORESOURCE_MEM_DRIVER_MANAGED	(1<<7)
 
 /* PnP I/O specific bits (IORESOURCE_BITS) */
 #define IORESOURCE_IO_16BIT_ADDR	(1<<0)
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index ca40bef75a616..dfeeed1aed084 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -520,7 +520,7 @@ static int locate_mem_hole_callback(struct resource *res,
void *arg)
 	/* Returning 0 will take to next memory range */
 
 	/* Don't use memory that will be detected and handled by a driver. */
-	if (res->flags & IORESOURCE_MEM_DRIVER_MANAGED)
+	if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
 		return 0;
 
 	if (sz < kbuf->memsz)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 4c47b68a9f4b5..8e1cd18b5cf14 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -105,7 +105,7 @@ static struct resource *register_memory_resource(u64 start,
u64 size,
 	unsigned long flags =  IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
 
 	if (strcmp(resource_name, "System RAM"))
-		flags |= IORESOURCE_MEM_DRIVER_MANAGED;
+		flags |= IORESOURCE_SYSRAM_DRIVER_MANAGED;
 
 	/*
 	 * Make sure value parsed from 'mem=' only restricts memory adding
@@ -1160,7 +1160,7 @@ EXPORT_SYMBOL_GPL(add_memory);
  *
  * For this memory, no entries in /sys/firmware/memmap ("raw
firmware-provided
  * memory map") are created. Also, the created memory resource is flagged
- * with IORESOURCE_MEM_DRIVER_MANAGED, so in-kernel users can special-case
+ * with IORESOURCE_SYSRAM_DRIVER_MANAGED, so in-kernel users can special-case
  * this memory as well (esp., not place kexec images onto it).
  *
  * The resource_name (visible via /proc/iomem) has to have the format
-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 3/7] mm/memory_hotplug: prepare passing flags to add_memory() and friends

We soon want to pass flags, e.g., to mark added System RAM resources.
mergeable. Prepare for that.

This patch is based on a similar patch by Oscar Salvador:

https://lkml.kernel.org/r/20190625075227.15193-3-osalvador at suse.de

Acked-by: Wei Liu <wei.liu at kernel.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Jason Gunthorpe <jgg at ziepe.ca>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Paul Mackerras <paulus at samba.org>
Cc: "Rafael J. Wysocki" <rjw at rjwysocki.net>
Cc: Len Brown <lenb at kernel.org>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Vishal Verma <vishal.l.verma at intel.com>
Cc: Dave Jiang <dave.jiang at intel.com>
Cc: "K. Y. Srinivasan" <kys at microsoft.com>
Cc: Haiyang Zhang <haiyangz at microsoft.com>
Cc: Stephen Hemminger <sthemmin at microsoft.com>
Cc: Wei Liu <wei.liu at kernel.org>
Cc: Heiko Carstens <hca at linux.ibm.com>
Cc: Vasily Gorbik <gor at linux.ibm.com>
Cc: Christian Borntraeger <borntraeger at de.ibm.com>
Cc: David Hildenbrand <david at redhat.com>
Cc: "Michael S. Tsirkin" <mst at redhat.com>
Cc: Jason Wang <jasowang at redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Cc: Juergen Gross <jgross at suse.com>
Cc: Stefano Stabellini <sstabellini at kernel.org>
Cc: "Oliver O'Halloran" <oohall at gmail.com>
Cc: Pingfan Liu <kernelfans at gmail.com>
Cc: Nathan Lynch <nathanl at linux.ibm.com>
Cc: Libor Pechacek <lpechacek at suse.cz>
Cc: Anton Blanchard <anton at ozlabs.org>
Cc: Leonardo Bras <leobras.c at gmail.com>
Cc: linuxppc-dev at lists.ozlabs.org
Cc: linux-acpi at vger.kernel.org
Cc: linux-nvdimm at lists.01.org
Cc: linux-hyperv at vger.kernel.org
Cc: linux-s390 at vger.kernel.org
Cc: virtualization at lists.linux-foundation.org
Cc: xen-devel at lists.xenproject.org
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 arch/powerpc/platforms/powernv/memtrace.c       |  2 +-
 arch/powerpc/platforms/pseries/hotplug-memory.c |  2 +-
 drivers/acpi/acpi_memhotplug.c                  |  2 +-
 drivers/base/memory.c                           |  2 +-
 drivers/dax/kmem.c                              |  2 +-
 drivers/hv/hv_balloon.c                         |  2 +-
 drivers/s390/char/sclp_cmd.c                    |  2 +-
 drivers/virtio/virtio_mem.c                     |  2 +-
 drivers/xen/balloon.c                           |  2 +-
 include/linux/memory_hotplug.h                  | 10 ++++++----
 mm/memory_hotplug.c                             | 15 ++++++++-------
 11 files changed, 23 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/memtrace.c
b/arch/powerpc/platforms/powernv/memtrace.c
index 13b369d2cc454..a7475d18c671c 100644
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -224,7 +224,7 @@ static int memtrace_online(void)
 			ent->mem = 0;
 		}
 
-		if (add_memory(ent->nid, ent->start, ent->size)) {
+		if (add_memory(ent->nid, ent->start, ent->size, 0)) {
 			pr_err("Failed to add trace memory to node %d\n",
 				ent->nid);
 			ret += 1;
diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c
b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 5d545b78111f9..54a888ea7f751 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -606,7 +606,7 @@ static int dlpar_add_lmb(struct drmem_lmb *lmb)
 	block_sz = memory_block_size_bytes();
 
 	/* Add the memory */
-	rc = __add_memory(lmb->nid, lmb->base_addr, block_sz);
+	rc = __add_memory(lmb->nid, lmb->base_addr, block_sz, 0);
 	if (rc) {
 		invalidate_lmb_associativity_index(lmb);
 		return rc;
diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
index e294f44a78504..d91b3584d4b2b 100644
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -207,7 +207,7 @@ static int acpi_memory_enable_device(struct
acpi_memory_device *mem_device)
 		if (node < 0)
 			node = memory_add_physaddr_to_nid(info->start_addr);
 
-		result = __add_memory(node, info->start_addr, info->length);
+		result = __add_memory(node, info->start_addr, info->length, 0);
 
 		/*
 		 * If the memory block has been used by the kernel, add_memory()
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 4db3c660de831..2287bcf86480e 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -432,7 +432,7 @@ static ssize_t probe_store(struct device *dev, struct
device_attribute *attr,
 
 	nid = memory_add_physaddr_to_nid(phys_addr);
 	ret = __add_memory(nid, phys_addr,
-			   MIN_MEMORY_BLOCK_SIZE * sections_per_block);
+			   MIN_MEMORY_BLOCK_SIZE * sections_per_block, 0);
 
 	if (ret)
 		goto out;
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 7dcb2902e9b1b..8e66b28ef5bc6 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -95,7 +95,7 @@ int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 		 * this as RAM automatically.
 		 */
 		rc = add_memory_driver_managed(numa_node, range.start,
-				range_len(&range), kmem_name);
+				range_len(&range), kmem_name, 0);
 
 		res->flags |= IORESOURCE_BUSY;
 		if (rc) {
diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 32e3bc0aa665a..0194bed1a5736 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -726,7 +726,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned
long size,
 
 		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
 		ret = add_memory(nid, PFN_PHYS((start_pfn)),
-				(HA_CHUNK << PAGE_SHIFT));
+				(HA_CHUNK << PAGE_SHIFT), 0);
 
 		if (ret) {
 			pr_err("hot_add memory failed error is %d\n", ret);
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index a864b21af602a..a6a908244c742 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -406,7 +406,7 @@ static void __init add_memory_merged(u16 rn)
 	if (!size)
 		goto skip_add;
 	for (addr = start; addr < start + size; addr += block_size)
-		add_memory(0, addr, block_size);
+		add_memory(0, addr, block_size, 0);
 skip_add:
 	first_rn = rn;
 	num = 1;
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 834b7c13ef3dc..314ab753139d1 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -424,7 +424,7 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned
long mb_id)
 
 	dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n",
mb_id);
 	return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
-					 vm->resource_name);
+					 vm->resource_name, 0);
 }
 
 /*
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 51427c752b37b..7bac38764513d 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -331,7 +331,7 @@ static enum bp_state reserve_additional_memory(void)
 	mutex_unlock(&balloon_mutex);
 	/* add_memory_resource() requires the device_hotplug lock */
 	lock_device_hotplug();
-	rc = add_memory_resource(nid, resource);
+	rc = add_memory_resource(nid, resource, 0);
 	unlock_device_hotplug();
 	mutex_lock(&balloon_mutex);
 
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 51a877fec8da8..5cd48332ce119 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -345,11 +345,13 @@ extern void set_zone_contiguous(struct zone *zone);
 extern void clear_zone_contiguous(struct zone *zone);
 
 extern void __ref free_area_init_core_hotplug(int nid);
-extern int __add_memory(int nid, u64 start, u64 size);
-extern int add_memory(int nid, u64 start, u64 size);
-extern int add_memory_resource(int nid, struct resource *resource);
+extern int __add_memory(int nid, u64 start, u64 size, unsigned long flags);
+extern int add_memory(int nid, u64 start, u64 size, unsigned long flags);
+extern int add_memory_resource(int nid, struct resource *resource,
+			       unsigned long flags);
 extern int add_memory_driver_managed(int nid, u64 start, u64 size,
-				     const char *resource_name);
+				     const char *resource_name,
+				     unsigned long flags);
 extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
 				   unsigned long nr_pages,
 				   struct vmem_altmap *altmap, int migratetype);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 8e1cd18b5cf14..64b07f006bc10 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1039,7 +1039,8 @@ static int online_memory_block(struct memory_block *mem,
void *arg)
  *
  * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
  */
-int __ref add_memory_resource(int nid, struct resource *res)
+int __ref add_memory_resource(int nid, struct resource *res,
+			      unsigned long flags)
 {
 	struct mhp_params params = { .pgprot = PAGE_KERNEL };
 	u64 start, size;
@@ -1118,7 +1119,7 @@ int __ref add_memory_resource(int nid, struct resource
*res)
 }
 
 /* requires device_hotplug_lock, see add_memory_resource() */
-int __ref __add_memory(int nid, u64 start, u64 size)
+int __ref __add_memory(int nid, u64 start, u64 size, unsigned long flags)
 {
 	struct resource *res;
 	int ret;
@@ -1127,18 +1128,18 @@ int __ref __add_memory(int nid, u64 start, u64 size)
 	if (IS_ERR(res))
 		return PTR_ERR(res);
 
-	ret = add_memory_resource(nid, res);
+	ret = add_memory_resource(nid, res, flags);
 	if (ret < 0)
 		release_memory_resource(res);
 	return ret;
 }
 
-int add_memory(int nid, u64 start, u64 size)
+int add_memory(int nid, u64 start, u64 size, unsigned long flags)
 {
 	int rc;
 
 	lock_device_hotplug();
-	rc = __add_memory(nid, start, size);
+	rc = __add_memory(nid, start, size, flags);
 	unlock_device_hotplug();
 
 	return rc;
@@ -1167,7 +1168,7 @@ EXPORT_SYMBOL_GPL(add_memory);
  * "System RAM ($DRIVER)".
  */
 int add_memory_driver_managed(int nid, u64 start, u64 size,
-			      const char *resource_name)
+			      const char *resource_name, unsigned long flags)
 {
 	struct resource *res;
 	int rc;
@@ -1185,7 +1186,7 @@ int add_memory_driver_managed(int nid, u64 start, u64
size,
 		goto out_unlock;
 	}
 
-	rc = add_memory_resource(nid, res);
+	rc = add_memory_resource(nid, res, flags);
 	if (rc < 0)
 		release_memory_resource(res);
 
-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 4/7] mm/memory_hotplug: MEMHP_MERGE_RESOURCE to specify merging of System RAM resources

Some add_memory*() users add memory in small, contiguous memory blocks.
Examples include virtio-mem, hyper-v balloon, and the XEN balloon.

This can quickly result in a lot of memory resources, whereby the actual
resource boundaries are not of interest (e.g., it might be relevant for
DIMMs, exposed via /proc/iomem to user space). We really want to merge
added resources in this scenario where possible.

Let's provide a flag (MEMHP_MERGE_RESOURCE) to specify that a resource
either created within add_memory*() or passed via add_memory_resource()
shall be marked mergeable and merged with applicable siblings.

To implement that, we need a kernel/resource interface to mark selected
System RAM resources mergeable (IORESOURCE_SYSRAM_MERGEABLE) and trigger
merging.

Note: We really want to merge after the whole operation succeeded, not
directly when adding a resource to the resource tree (it would break
add_memory_resource() and require splitting resources again when the
operation failed - e.g., due to -ENOMEM).

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Jason Gunthorpe <jgg at ziepe.ca>
Cc: Kees Cook <keescook at chromium.org>
Cc: Ard Biesheuvel <ardb at kernel.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: "K. Y. Srinivasan" <kys at microsoft.com>
Cc: Haiyang Zhang <haiyangz at microsoft.com>
Cc: Stephen Hemminger <sthemmin at microsoft.com>
Cc: Wei Liu <wei.liu at kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Cc: Juergen Gross <jgross at suse.com>
Cc: Stefano Stabellini <sstabellini at kernel.org>
Cc: Roger Pau Monn? <roger.pau at citrix.com>
Cc: Julien Grall <julien at xen.org>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 include/linux/ioport.h         |  4 +++
 include/linux/memory_hotplug.h |  9 +++++
 kernel/resource.c              | 60 ++++++++++++++++++++++++++++++++++
 mm/memory_hotplug.c            |  7 ++++
 4 files changed, 80 insertions(+)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index d7620d7c941a0..7e61389dcb017 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -60,6 +60,7 @@ struct resource {
 
 /* IORESOURCE_SYSRAM specific bits. */
 #define IORESOURCE_SYSRAM_DRIVER_MANAGED	0x02000000 /* Always detected via a
driver. */
+#define IORESOURCE_SYSRAM_MERGEABLE		0x04000000 /* Resource can be merged. */
 
 #define IORESOURCE_EXCLUSIVE	0x08000000	/* Userland may not map this resource
*/
 
@@ -253,6 +254,9 @@ extern void __release_region(struct resource *,
resource_size_t,
 extern void release_mem_region_adjustable(struct resource *, resource_size_t,
 					  resource_size_t);
 #endif
+#ifdef CONFIG_MEMORY_HOTPLUG
+extern void merge_system_ram_resource(struct resource *res);
+#endif
 
 /* Wrappers for managed devices */
 struct device;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 5cd48332ce119..feb4aac03f2eb 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -68,6 +68,15 @@ struct mhp_params {
 	pgprot_t pgprot;
 };
 
+/* Flags used for add_memory() and friends. */
+
+/*
+ * Allow merging of the added System RAM resource with adjacent, mergeable
+ * resources. After a successful call to add_memory_resource() with this flag
+ * set, the resource pointer must no longer be used as it might be stale.
+ */
+#define MEMHP_MERGE_RESOURCE		1
+
 /*
  * Zone resizing functions
  *
diff --git a/kernel/resource.c b/kernel/resource.c
index 36b3552210120..7a91b935f4c20 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1363,6 +1363,66 @@ void release_mem_region_adjustable(struct resource
*parent,
 }
 #endif	/* CONFIG_MEMORY_HOTREMOVE */
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+static bool system_ram_resources_mergeable(struct resource *r1,
+					   struct resource *r2)
+{
+	/* We assume either r1 or r2 is IORESOURCE_SYSRAM_MERGEABLE. */
+	return r1->flags == r2->flags && r1->end + 1 == r2->start
&&
+	       r1->name == r2->name && r1->desc == r2->desc
&&
+	       !r1->child && !r2->child;
+}
+
+/*
+ * merge_system_ram_resource - mark the System RAM resource mergeable and try
to
+ * merge it with adjacent, mergeable resources
+ * @res: resource descriptor
+ *
+ * This interface is intended for memory hotplug, whereby lots of contiguous
+ * system ram resources are added (e.g., via add_memory*()) by a driver, and
+ * the actual resource boundaries are not of interest (e.g., it might be
+ * relevant for DIMMs). Only resources that are marked mergeable, that have the
+ * same parent, and that don't have any children are considered. All
mergeable
+ * resources must be immutable during the request.
+ *
+ * Note:
+ * - The caller has to make sure that no pointers to resources that are
+ *   marked mergeable are used anymore after this call - the resource might
+ *   be freed and the pointer might be stale!
+ * - release_mem_region_adjustable() will split on demand on memory hotunplug
+ */
+void merge_system_ram_resource(struct resource *res)
+{
+	const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+	struct resource *cur;
+
+	if (WARN_ON_ONCE((res->flags & flags) != flags))
+		return;
+
+	write_lock(&resource_lock);
+	res->flags |= IORESOURCE_SYSRAM_MERGEABLE;
+
+	/* Try to merge with next item in the list. */
+	cur = res->sibling;
+	if (cur && system_ram_resources_mergeable(res, cur)) {
+		res->end = cur->end;
+		res->sibling = cur->sibling;
+		free_resource(cur);
+	}
+
+	/* Try to merge with previous item in the list. */
+	cur = res->parent->child;
+	while (cur && cur->sibling != res)
+		cur = cur->sibling;
+	if (cur && system_ram_resources_mergeable(cur, res)) {
+		cur->end = res->end;
+		cur->sibling = res->sibling;
+		free_resource(res);
+	}
+	write_unlock(&resource_lock);
+}
+#endif	/* CONFIG_MEMORY_HOTPLUG */
+
 /*
  * Managed region resource
  */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 64b07f006bc10..f62c2a46df8b1 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1103,6 +1103,13 @@ int __ref add_memory_resource(int nid, struct resource
*res,
 	/* device_online() will take the lock when calling online_pages() */
 	mem_hotplug_done();
 
+	/*
+	 * In case we're allowed to merge the resource, flag it and trigger
+	 * merging now that adding succeeded.
+	 */
+	if (flags & MEMHP_MERGE_RESOURCE)
+		merge_system_ram_resource(res);
+
 	/* online pages if requested */
 	if (memhp_default_online_type != MMOP_OFFLINE)
 		walk_memory_blocks(start, size, NULL, online_memory_block);
-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 5/7] virtio-mem: try to merge system ram resources

virtio-mem adds memory in memory block granularity, to be able to
remove it in the same granularity again later, and to grow slowly on
demand. This, however, results in quite a lot of resources when
adding a lot of memory. Resources are effectively stored in a list-based
tree. Having a lot of resources not only wastes memory, it also makes
traversing that tree more expensive, and makes /proc/iomem explode in
size (e.g., requiring kexec-tools to manually merge resources later
when e.g., trying to create a kdump header).

Before this patch, we get (/proc/iomem) when hotplugging 2G via virtio-mem
on x86-64:
        [...]
        100000000-13fffffff : System RAM
        140000000-33fffffff : virtio0
          140000000-147ffffff : System RAM (virtio_mem)
          148000000-14fffffff : System RAM (virtio_mem)
          150000000-157ffffff : System RAM (virtio_mem)
          158000000-15fffffff : System RAM (virtio_mem)
          160000000-167ffffff : System RAM (virtio_mem)
          168000000-16fffffff : System RAM (virtio_mem)
          170000000-177ffffff : System RAM (virtio_mem)
          178000000-17fffffff : System RAM (virtio_mem)
          180000000-187ffffff : System RAM (virtio_mem)
          188000000-18fffffff : System RAM (virtio_mem)
          190000000-197ffffff : System RAM (virtio_mem)
          198000000-19fffffff : System RAM (virtio_mem)
          1a0000000-1a7ffffff : System RAM (virtio_mem)
          1a8000000-1afffffff : System RAM (virtio_mem)
          1b0000000-1b7ffffff : System RAM (virtio_mem)
          1b8000000-1bfffffff : System RAM (virtio_mem)
        3280000000-32ffffffff : PCI Bus 0000:00

With this patch, we get (/proc/iomem):
        [...]
        fffc0000-ffffffff : Reserved
        100000000-13fffffff : System RAM
        140000000-33fffffff : virtio0
          140000000-1bfffffff : System RAM (virtio_mem)
        3280000000-32ffffffff : PCI Bus 0000:00

Of course, with more hotplugged memory, it gets worse. When unplugging
memory blocks again, try_remove_memory() (via
offline_and_remove_memory()) will properly split the resource up again.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Michael S. Tsirkin <mst at redhat.com>
Cc: Jason Wang <jasowang at redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 drivers/virtio/virtio_mem.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 314ab753139d1..ba4de598f6636 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -424,7 +424,8 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned
long mb_id)
 
 	dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n",
mb_id);
 	return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
-					 vm->resource_name, 0);
+					 vm->resource_name,
+					 MEMHP_MERGE_RESOURCE);
 }
 
 /*
-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 6/7] xen/balloon: try to merge system ram resources

Let's try to merge system ram resources we add, to minimize the number
of resources in /proc/iomem. We don't care about the boundaries of
individual chunks we added.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Cc: Juergen Gross <jgross at suse.com>
Cc: Stefano Stabellini <sstabellini at kernel.org>
Cc: Roger Pau Monn? <roger.pau at citrix.com>
Cc: Julien Grall <julien at xen.org>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 drivers/xen/balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 7bac38764513d..b57b2067ecbfb 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -331,7 +331,7 @@ static enum bp_state reserve_additional_memory(void)
 	mutex_unlock(&balloon_mutex);
 	/* add_memory_resource() requires the device_hotplug lock */
 	lock_device_hotplug();
-	rc = add_memory_resource(nid, resource, 0);
+	rc = add_memory_resource(nid, resource, MEMHP_MERGE_RESOURCE);
 	unlock_device_hotplug();
 	mutex_lock(&balloon_mutex);
 
-- 
2.26.2

David Hildenbrand

2020-Sep-08 20:10 UTC

head link

[PATCH v2 7/7] hv_balloon: try to merge system ram resources

Let's try to merge system ram resources we add, to minimize the number
of resources in /proc/iomem. We don't care about the boundaries of
individual chunks we added.

Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Michal Hocko <mhocko at suse.com>
Cc: "K. Y. Srinivasan" <kys at microsoft.com>
Cc: Haiyang Zhang <haiyangz at microsoft.com>
Cc: Stephen Hemminger <sthemmin at microsoft.com>
Cc: Wei Liu <wei.liu at kernel.org>
Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
Cc: Baoquan He <bhe at redhat.com>
Cc: Wei Yang <richardw.yang at linux.intel.com>
Signed-off-by: David Hildenbrand <david at redhat.com>
---
 drivers/hv/hv_balloon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 0194bed1a5736..b64d2efbefe71 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -726,7 +726,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned
long size,
 
 		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
 		ret = add_memory(nid, PFN_PHYS((start_pfn)),
-				(HA_CHUNK << PAGE_SHIFT), 0);
+				(HA_CHUNK << PAGE_SHIFT), MEMHP_MERGE_RESOURCE);
 
 		if (ret) {
 			pr_err("hot_add memory failed error is %d\n", ret);
-- 
2.26.2

Jürgen Groß

2020-Sep-09 05:18 UTC

head link

[PATCH v2 3/7] mm/memory_hotplug: prepare passing flags to add_memory() and friends

On 08.09.20 22:10, David Hildenbrand wrote:> We soon want to pass flags, e.g., to mark added System RAM resources.
> mergeable. Prepare for that.
> 
> This patch is based on a similar patch by Oscar Salvador:
> 
> https://lkml.kernel.org/r/20190625075227.15193-3-osalvador at suse.de
> 
> Acked-by: Wei Liu <wei.liu at kernel.org>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: Michal Hocko <mhocko at suse.com>
> Cc: Dan Williams <dan.j.williams at intel.com>
> Cc: Jason Gunthorpe <jgg at ziepe.ca>
> Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
> Cc: Baoquan He <bhe at redhat.com>
> Cc: Wei Yang <richardw.yang at linux.intel.com>
> Cc: Michael Ellerman <mpe at ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> Cc: Paul Mackerras <paulus at samba.org>
> Cc: "Rafael J. Wysocki" <rjw at rjwysocki.net>
> Cc: Len Brown <lenb at kernel.org>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: Vishal Verma <vishal.l.verma at intel.com>
> Cc: Dave Jiang <dave.jiang at intel.com>
> Cc: "K. Y. Srinivasan" <kys at microsoft.com>
> Cc: Haiyang Zhang <haiyangz at microsoft.com>
> Cc: Stephen Hemminger <sthemmin at microsoft.com>
> Cc: Wei Liu <wei.liu at kernel.org>
> Cc: Heiko Carstens <hca at linux.ibm.com>
> Cc: Vasily Gorbik <gor at linux.ibm.com>
> Cc: Christian Borntraeger <borntraeger at de.ibm.com>
> Cc: David Hildenbrand <david at redhat.com>
> Cc: "Michael S. Tsirkin" <mst at redhat.com>
> Cc: Jason Wang <jasowang at redhat.com>
> Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
> Cc: Juergen Gross <jgross at suse.com>
> Cc: Stefano Stabellini <sstabellini at kernel.org>
> Cc: "Oliver O'Halloran" <oohall at gmail.com>
> Cc: Pingfan Liu <kernelfans at gmail.com>
> Cc: Nathan Lynch <nathanl at linux.ibm.com>
> Cc: Libor Pechacek <lpechacek at suse.cz>
> Cc: Anton Blanchard <anton at ozlabs.org>
> Cc: Leonardo Bras <leobras.c at gmail.com>
> Cc: linuxppc-dev at lists.ozlabs.org
> Cc: linux-acpi at vger.kernel.org
> Cc: linux-nvdimm at lists.01.org
> Cc: linux-hyperv at vger.kernel.org
> Cc: linux-s390 at vger.kernel.org
> Cc: virtualization at lists.linux-foundation.org
> Cc: xen-devel at lists.xenproject.org
> Signed-off-by: David Hildenbrand <david at redhat.com>
Reviewed-by: Juergen Gross <jgross at suse.com> (Xen related part)


Juergen
> ---
>   arch/powerpc/platforms/powernv/memtrace.c       |  2 +-
>   arch/powerpc/platforms/pseries/hotplug-memory.c |  2 +-
>   drivers/acpi/acpi_memhotplug.c                  |  2 +-
>   drivers/base/memory.c                           |  2 +-
>   drivers/dax/kmem.c                              |  2 +-
>   drivers/hv/hv_balloon.c                         |  2 +-
>   drivers/s390/char/sclp_cmd.c                    |  2 +-
>   drivers/virtio/virtio_mem.c                     |  2 +-
>   drivers/xen/balloon.c                           |  2 +-
>   include/linux/memory_hotplug.h                  | 10 ++++++----
>   mm/memory_hotplug.c                             | 15 ++++++++-------
>   11 files changed, 23 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/memtrace.c
b/arch/powerpc/platforms/powernv/memtrace.c
> index 13b369d2cc454..a7475d18c671c 100644
> --- a/arch/powerpc/platforms/powernv/memtrace.c
> +++ b/arch/powerpc/platforms/powernv/memtrace.c
> @@ -224,7 +224,7 @@ static int memtrace_online(void)
>   			ent->mem = 0;
>   		}
>   
> -		if (add_memory(ent->nid, ent->start, ent->size)) {
> +		if (add_memory(ent->nid, ent->start, ent->size, 0)) {
>   			pr_err("Failed to add trace memory to node %d\n",
>   				ent->nid);
>   			ret += 1;
> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c
b/arch/powerpc/platforms/pseries/hotplug-memory.c
> index 5d545b78111f9..54a888ea7f751 100644
> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c
> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
> @@ -606,7 +606,7 @@ static int dlpar_add_lmb(struct drmem_lmb *lmb)
>   	block_sz = memory_block_size_bytes();
>   
>   	/* Add the memory */
> -	rc = __add_memory(lmb->nid, lmb->base_addr, block_sz);
> +	rc = __add_memory(lmb->nid, lmb->base_addr, block_sz, 0);
>   	if (rc) {
>   		invalidate_lmb_associativity_index(lmb);
>   		return rc;
> diff --git a/drivers/acpi/acpi_memhotplug.c
b/drivers/acpi/acpi_memhotplug.c
> index e294f44a78504..d91b3584d4b2b 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -207,7 +207,7 @@ static int acpi_memory_enable_device(struct
acpi_memory_device *mem_device)
>   		if (node < 0)
>   			node = memory_add_physaddr_to_nid(info->start_addr);
>   
> -		result = __add_memory(node, info->start_addr, info->length);
> +		result = __add_memory(node, info->start_addr, info->length, 0);
>   
>   		/*
>   		 * If the memory block has been used by the kernel, add_memory()
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 4db3c660de831..2287bcf86480e 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -432,7 +432,7 @@ static ssize_t probe_store(struct device *dev, struct
device_attribute *attr,
>   
>   	nid = memory_add_physaddr_to_nid(phys_addr);
>   	ret = __add_memory(nid, phys_addr,
> -			   MIN_MEMORY_BLOCK_SIZE * sections_per_block);
> +			   MIN_MEMORY_BLOCK_SIZE * sections_per_block, 0);
>   
>   	if (ret)
>   		goto out;
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index 7dcb2902e9b1b..8e66b28ef5bc6 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -95,7 +95,7 @@ int dev_dax_kmem_probe(struct dev_dax *dev_dax)
>   		 * this as RAM automatically.
>   		 */
>   		rc = add_memory_driver_managed(numa_node, range.start,
> -				range_len(&range), kmem_name);
> +				range_len(&range), kmem_name, 0);
>   
>   		res->flags |= IORESOURCE_BUSY;
>   		if (rc) {
> diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
> index 32e3bc0aa665a..0194bed1a5736 100644
> --- a/drivers/hv/hv_balloon.c
> +++ b/drivers/hv/hv_balloon.c
> @@ -726,7 +726,7 @@ static void hv_mem_hot_add(unsigned long start,
unsigned long size,
>   
>   		nid = memory_add_physaddr_to_nid(PFN_PHYS(start_pfn));
>   		ret = add_memory(nid, PFN_PHYS((start_pfn)),
> -				(HA_CHUNK << PAGE_SHIFT));
> +				(HA_CHUNK << PAGE_SHIFT), 0);
>   
>   		if (ret) {
>   			pr_err("hot_add memory failed error is %d\n", ret);
> diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
> index a864b21af602a..a6a908244c742 100644
> --- a/drivers/s390/char/sclp_cmd.c
> +++ b/drivers/s390/char/sclp_cmd.c
> @@ -406,7 +406,7 @@ static void __init add_memory_merged(u16 rn)
>   	if (!size)
>   		goto skip_add;
>   	for (addr = start; addr < start + size; addr += block_size)
> -		add_memory(0, addr, block_size);
> +		add_memory(0, addr, block_size, 0);
>   skip_add:
>   	first_rn = rn;
>   	num = 1;
> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index 834b7c13ef3dc..314ab753139d1 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -424,7 +424,7 @@ static int virtio_mem_mb_add(struct virtio_mem *vm,
unsigned long mb_id)
>   
>   	dev_dbg(&vm->vdev->dev, "adding memory block:
%lu\n", mb_id);
>   	return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
> -					 vm->resource_name);
> +					 vm->resource_name, 0);
>   }
>   
>   /*
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 51427c752b37b..7bac38764513d 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -331,7 +331,7 @@ static enum bp_state reserve_additional_memory(void)
>   	mutex_unlock(&balloon_mutex);
>   	/* add_memory_resource() requires the device_hotplug lock */
>   	lock_device_hotplug();
> -	rc = add_memory_resource(nid, resource);
> +	rc = add_memory_resource(nid, resource, 0);
>   	unlock_device_hotplug();
>   	mutex_lock(&balloon_mutex);
>   
> diff --git a/include/linux/memory_hotplug.h
b/include/linux/memory_hotplug.h
> index 51a877fec8da8..5cd48332ce119 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -345,11 +345,13 @@ extern void set_zone_contiguous(struct zone *zone);
>   extern void clear_zone_contiguous(struct zone *zone);
>   
>   extern void __ref free_area_init_core_hotplug(int nid);
> -extern int __add_memory(int nid, u64 start, u64 size);
> -extern int add_memory(int nid, u64 start, u64 size);
> -extern int add_memory_resource(int nid, struct resource *resource);
> +extern int __add_memory(int nid, u64 start, u64 size, unsigned long
flags);
> +extern int add_memory(int nid, u64 start, u64 size, unsigned long flags);
> +extern int add_memory_resource(int nid, struct resource *resource,
> +			       unsigned long flags);
>   extern int add_memory_driver_managed(int nid, u64 start, u64 size,
> -				     const char *resource_name);
> +				     const char *resource_name,
> +				     unsigned long flags);
>   extern void move_pfn_range_to_zone(struct zone *zone, unsigned long
start_pfn,
>   				   unsigned long nr_pages,
>   				   struct vmem_altmap *altmap, int migratetype);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 8e1cd18b5cf14..64b07f006bc10 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1039,7 +1039,8 @@ static int online_memory_block(struct memory_block
*mem, void *arg)
>    *
>    * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
>    */
> -int __ref add_memory_resource(int nid, struct resource *res)
> +int __ref add_memory_resource(int nid, struct resource *res,
> +			      unsigned long flags)
>   {
>   	struct mhp_params params = { .pgprot = PAGE_KERNEL };
>   	u64 start, size;
> @@ -1118,7 +1119,7 @@ int __ref add_memory_resource(int nid, struct
resource *res)
>   }
>   
>   /* requires device_hotplug_lock, see add_memory_resource() */
> -int __ref __add_memory(int nid, u64 start, u64 size)
> +int __ref __add_memory(int nid, u64 start, u64 size, unsigned long flags)
>   {
>   	struct resource *res;
>   	int ret;
> @@ -1127,18 +1128,18 @@ int __ref __add_memory(int nid, u64 start, u64
size)
>   	if (IS_ERR(res))
>   		return PTR_ERR(res);
>   
> -	ret = add_memory_resource(nid, res);
> +	ret = add_memory_resource(nid, res, flags);
>   	if (ret < 0)
>   		release_memory_resource(res);
>   	return ret;
>   }
>   
> -int add_memory(int nid, u64 start, u64 size)
> +int add_memory(int nid, u64 start, u64 size, unsigned long flags)
>   {
>   	int rc;
>   
>   	lock_device_hotplug();
> -	rc = __add_memory(nid, start, size);
> +	rc = __add_memory(nid, start, size, flags);
>   	unlock_device_hotplug();
>   
>   	return rc;
> @@ -1167,7 +1168,7 @@ EXPORT_SYMBOL_GPL(add_memory);
>    * "System RAM ($DRIVER)".
>    */
>   int add_memory_driver_managed(int nid, u64 start, u64 size,
> -			      const char *resource_name)
> +			      const char *resource_name, unsigned long flags)
>   {
>   	struct resource *res;
>   	int rc;
> @@ -1185,7 +1186,7 @@ int add_memory_driver_managed(int nid, u64 start, u64
size,
>   		goto out_unlock;
>   	}
>   
> -	rc = add_memory_resource(nid, res);
> +	rc = add_memory_resource(nid, res, flags);
>   	if (rc < 0)
>   		release_memory_resource(res);
>   
>

Jürgen Groß

2020-Sep-09 05:18 UTC

head link

[PATCH v2 6/7] xen/balloon: try to merge system ram resources

On 08.09.20 22:10, David Hildenbrand wrote:> Let's try to merge system ram resources we add, to minimize the number
> of resources in /proc/iomem. We don't care about the boundaries of
> individual chunks we added.
> 
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: Michal Hocko <mhocko at suse.com>
> Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
> Cc: Juergen Gross <jgross at suse.com>
> Cc: Stefano Stabellini <sstabellini at kernel.org>
> Cc: Roger Pau Monn? <roger.pau at citrix.com>
> Cc: Julien Grall <julien at xen.org>
> Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
> Cc: Baoquan He <bhe at redhat.com>
> Cc: Wei Yang <richardw.yang at linux.intel.com>
> Signed-off-by: David Hildenbrand <david at redhat.com>
Reviewed-by: Juergen Gross <jgross at suse.com>

Juergen
> ---
>   drivers/xen/balloon.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 7bac38764513d..b57b2067ecbfb 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -331,7 +331,7 @@ static enum bp_state reserve_additional_memory(void)
>   	mutex_unlock(&balloon_mutex);
>   	/* add_memory_resource() requires the device_hotplug lock */
>   	lock_device_hotplug();
> -	rc = add_memory_resource(nid, resource, 0);
> +	rc = add_memory_resource(nid, resource, MEMHP_MERGE_RESOURCE);
>   	unlock_device_hotplug();
>   	mutex_lock(&balloon_mutex);
>   
>

Greg Kroah-Hartman

2020-Sep-09 07:16 UTC

head link

[PATCH v2 2/7] kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED

On Tue, Sep 08, 2020 at 10:10:07PM +0200, David Hildenbrand
wrote:> IORESOURCE_MEM_DRIVER_MANAGED currently uses an unused PnP bit, which is
> always set to 0 by hardware. This is far from beautiful (and confusing),
> and the bit only applies to SYSRAM. So let's move it out of the
> bus-specific (PnP) defined bits.
> 
> We'll add another SYSRAM specific bit soon. If we ever need more bits
for
> other purposes, we can steal some from "desc", or
reshuffle/regroup what we
> have.
> 
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: Michal Hocko <mhocko at suse.com>
> Cc: Dan Williams <dan.j.williams at intel.com>
> Cc: Jason Gunthorpe <jgg at ziepe.ca>
> Cc: Kees Cook <keescook at chromium.org>
> Cc: Ard Biesheuvel <ardb at kernel.org>
> Cc: Pankaj Gupta <pankaj.gupta.linux at gmail.com>
> Cc: Baoquan He <bhe at redhat.com>
> Cc: Wei Yang <richardw.yang at linux.intel.com>
> Cc: Eric Biederman <ebiederm at xmission.com>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: kexec at lists.infradead.org
> Signed-off-by: David Hildenbrand <david at redhat.com>
> ---
>  include/linux/ioport.h | 4 +++-
>  kernel/kexec_file.c    | 2 +-
>  mm/memory_hotplug.c    | 4 ++--
>  3 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 52a91f5fa1a36..d7620d7c941a0 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -58,6 +58,9 @@ struct resource {
>  #define IORESOURCE_EXT_TYPE_BITS 0x01000000	/* Resource extended types */
>  #define IORESOURCE_SYSRAM	0x01000000	/* System RAM (modifier) */
>  
> +/* IORESOURCE_SYSRAM specific bits. */
> +#define IORESOURCE_SYSRAM_DRIVER_MANAGED	0x02000000 /* Always detected via
a driver. */
> +
Can't you use BIT() here?

thanks,

greg k-h

Greg Kroah-Hartman

2020-Sep-09 07:17 UTC

head link

[PATCH v2 3/7] mm/memory_hotplug: prepare passing flags to add_memory() and friends

On Tue, Sep 08, 2020 at 10:10:08PM +0200, David Hildenbrand
wrote:> We soon want to pass flags, e.g., to mark added System RAM resources.
> mergeable. Prepare for that.
What are these random "flags", and how do we know what should be
passed
to them?

Why not make this an enumerated type so that we know it all works
properly, like the GPF_* flags are?  Passing around a random unsigned
long feels very odd/broken...

thanks,

greg k-h

David Hildenbrand

2020-Sep-15 07:35 UTC

head link

[PATCH v2 1/7] kernel/resource: make release_mem_region_adjustable() never fail

>> static int __ref try_remove_memory(int nid, u64 start, u64 size)
>> {
>> 	int rc = 0;
>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64
start, u64 size)
>> 		memblock_remove(start, size);
>> 	}
>>
>> -	__release_memory_resource(start, size);
>> +	release_mem_region_adjustable(&iomem_resource, start, size);
>>
> 
> Seems the only user of release_mem_region_adjustable() is here, can we move
> iomem_resource into the function body? Actually, we don't iterate the
resource
> tree from any level. We always start from the root.
You mean, making iomem_resource implicit? I can spot that something
similar was done for

#define devm_release_mem_region(dev, start, n) \
	__devm_release_region(dev, &iomem_resource, (start), (n))

I'll send an addon patch for that, ok? - thanks.

-- 
Thanks,

David / dhildenb

David Hildenbrand

2020-Sep-15 07:37 UTC

head link

[PATCH v2 2/7] kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED

On 15.09.20 04:20, Wei Yang wrote:> On Tue, Sep 08, 2020 at 10:10:07PM +0200, David Hildenbrand wrote:
>> IORESOURCE_MEM_DRIVER_MANAGED currently uses an unused PnP bit, which
is
>> always set to 0 by hardware. This is far from beautiful (and
confusing),
>> and the bit only applies to SYSRAM. So let's move it out of the
>> bus-specific (PnP) defined bits.
>>
>> We'll add another SYSRAM specific bit soon. If we ever need more
bits for
>> other purposes, we can steal some from "desc", or
reshuffle/regroup what we
>> have.
> 
> I think you make this definition because we use IORESOURCE_SYSRAM_RAM for
> hotpluged memory? So we make them all in IORESOURCE_SYSRAM_XXX family?
Yeah, to specify based on the extended MEM type SYSRAM. Because it
really only applies to that.

-- 
Thanks,

David / dhildenb

David Hildenbrand

2020-Sep-15 09:15 UTC

head link

[PATCH v2 1/7] kernel/resource: make release_mem_region_adjustable() never fail

On 15.09.20 11:06, Wei Yang wrote:> On Tue, Sep 15, 2020 at 09:35:30AM +0200, David Hildenbrand wrote:
>>
>>>> static int __ref try_remove_memory(int nid, u64 start, u64
size)
>>>> {
>>>> 	int rc = 0;
>>>> @@ -1777,7 +1757,7 @@ static int __ref try_remove_memory(int
nid, u64 start, u64 size)
>>>> 		memblock_remove(start, size);
>>>> 	}
>>>>
>>>> -	__release_memory_resource(start, size);
>>>> +	release_mem_region_adjustable(&iomem_resource, start,
size);
>>>>
>>>
>>> Seems the only user of release_mem_region_adjustable() is here, can
we move
>>> iomem_resource into the function body? Actually, we don't
iterate the resource
>>> tree from any level. We always start from the root.
>>
>> You mean, making iomem_resource implicit? I can spot that something
>> similar was done for
>>
>> #define devm_release_mem_region(dev, start, n) \
>> 	__devm_release_region(dev, &iomem_resource, (start), (n))
>>
> 
> What I prefer is remove iomem_resource from the parameter list. Just use is
in
> the function body.
> 
> For the example you listed, __release_region() would have varies of
*parent*,
> which looks reasonable to keep it here.
Yeah I got that ("making iomem_resource implicit"), as I said:
>> I'll send an addon patch for that, ok? - thanks.
-- 
Thanks,

David / dhildenb

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[PATCH v2 6/7] xen/balloon: try to merge system ram resources

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[PATCH v2 6/7] xen/balloon: try to merge system ram resources

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