On Mon, May 27, 2019 at 01:11:51PM +0200, David Hildenbrand wrote:
>We really don't want anything during memory hotunplug to fail.
>We always pass a valid memory block device, that check can go. Avoid
>allocating memory and eventually failing. As we are always called under
>lock, we can use a static piece of memory. This avoids having to put
>the structure onto the stack, having to guess about the stack size
>of callers.
>
>Patch inspired by a patch from Oscar Salvador.
>
>In the future, there might be no need to iterate over nodes at all.
>mem->nid should tell us exactly what to remove. Memory block devices
>with mixed nodes (added during boot) should properly fenced off and never
>removed.
>
>Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
>Cc: Alex Deucher <alexander.deucher@xxxxxxx>
>Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
>Cc: Mark Brown <broonie@xxxxxxxxxx>
>Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>Cc: David Hildenbrand <david@xxxxxxxxxx>
>Cc: Oscar Salvador <osalvador@xxxxxxx>
>Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
>Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
>---
> drivers/base/node.c | 18 +++++-------------
> include/linux/node.h | 5 ++---
> 2 files changed, 7 insertions(+), 16 deletions(-)
>
>diff --git a/drivers/base/node.c b/drivers/base/node.c
>index 04fdfa99b8bc..9be88fd05147 100644
>--- a/drivers/base/node.c
>+++ b/drivers/base/node.c
>@@ -803,20 +803,14 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, void *arg)
>
> /*
> * Unregister memory block device under all nodes that it spans.
>+ * Has to be called with mem_sysfs_mutex held (due to unlinked_nodes).
> */
>-int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
>+void unregister_memory_block_under_nodes(struct memory_block *mem_blk)
> {
>- NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
> unsigned long pfn, sect_start_pfn, sect_end_pfn;
>+ static nodemask_t unlinked_nodes;
>
>- if (!mem_blk) {
>- NODEMASK_FREE(unlinked_nodes);
>- return -EFAULT;
>- }
>- if (!unlinked_nodes)
>- return -ENOMEM;
>- nodes_clear(*unlinked_nodes);
>-
>+ nodes_clear(unlinked_nodes);
> sect_start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
> sect_end_pfn = section_nr_to_pfn(mem_blk->end_section_nr);
> for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
>@@ -827,15 +821,13 @@ int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
> continue;
> if (!node_online(nid))
> continue;
>- if (node_test_and_set(nid, *unlinked_nodes))
>+ if (node_test_and_set(nid, unlinked_nodes))
> continue;
> sysfs_remove_link(&node_devices[nid]->dev.kobj,
> kobject_name(&mem_blk->dev.kobj));
> sysfs_remove_link(&mem_blk->dev.kobj,
> kobject_name(&node_devices[nid]->dev.kobj));
> }
>- NODEMASK_FREE(unlinked_nodes);
>- return 0;
> }
>
> int link_mem_sections(int nid, unsigned long start_pfn, unsigned long end_pfn)
>diff --git a/include/linux/node.h b/include/linux/node.h
>index 02a29e71b175..548c226966a2 100644
>--- a/include/linux/node.h
>+++ b/include/linux/node.h
>@@ -139,7 +139,7 @@ extern int register_cpu_under_node(unsigned int cpu, unsigned int nid);
> extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
> extern int register_mem_sect_under_node(struct memory_block *mem_blk,
> void *arg);
>-extern int unregister_memory_block_under_nodes(struct memory_block *mem_blk);
>+extern void unregister_memory_block_under_nodes(struct memory_block *mem_blk);
>
> extern int register_memory_node_under_compute_node(unsigned int mem_nid,
> unsigned int cpu_nid,
>@@ -175,9 +175,8 @@ static inline int register_mem_sect_under_node(struct memory_block *mem_blk,
> {
> return 0;
> }
>-static inline int unregister_memory_block_under_nodes(struct memory_block *mem_blk)
>+static inline void unregister_memory_block_under_nodes(struct memory_block *mem_blk)
> {
>- return 0;
> }
>
> static inline void register_hugetlbfs_with_node(node_registration_func_t reg,
>--
>2.20.1
--
Wei Yang
Help you, Help me
