mm, memory_hotplug: move zone/pages handling to offline stage

The current implementation accesses pages during hot-remove stage in order
to get the zone linked to this memory-range.  We use that zone for a)
check if the zone is ZONE_DEVICE and b) to shrink the zone's spanned
pages.

Accessing pages during this stage is problematic, as we might be accessing
pages that were not initialized if we did not get to online the memory
before removing it.

The only reason to check for ZONE_DEVICE in __remove_pages is to bypass
the call to release_mem_region_adjustable(), since these regions are
removed with devm_release_mem_region.

With patch#2, this is no longer a problem so we can safely call
release_mem_region_adjustable().  release_mem_region_adjustable() will
spot that the region we are trying to remove was acquired by means of
devm_request_mem_region, and will back off safely.

This allows us to remove all zone-related operations from hot-remove
stage.

Because of this, zone's spanned pages are shrinked during the offlining
stage in shrink_zone_pgdat().  It would have been great to decrease also
the spanned page for the node there, but we need them in
try_offline_node().  So we still decrease spanned pages for the node in
the hot-remove stage.

The only particularity is that now
find_smallest_section_pfn/find_biggest_section_pfn, when called from
shrink_zone_span, will now check for online sections and not valid
sections instead.  To make this work with devm/HMM code, we need to call
offline_mem_sections and online_mem_sections in that code path when we are
adding memory.

Link: http://lkml.kernel.org/r/20181127162005.15833-4-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 40feb262080ed683b943644aba458487fdd2a58c..b3c9ee5c4f7874427cee913f3a48e583cb5e4239 100644 (file)
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -144,18 +144,9 @@ int __meminit arch_remove_memory(int nid, u64 start, u64 size,
 {
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
-       struct page *page;
        int ret;
 
-       /*
-        * If we have an altmap then we need to skip over any reserved PFNs
-        * when querying the zone.
-        */
-       page = pfn_to_page(start_pfn);
-       if (altmap)
-               page += vmem_altmap_offset(altmap);
-
-       ret = __remove_pages(page_zone(page), start_pfn, nr_pages, altmap);
+       ret = remove_sections(nid, start_pfn, nr_pages, altmap);
        if (ret)
                return ret;
 

diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index a8e5c0e00fcaef3d85a0ce595db38fbe36c46532..1a483a008872f868ba20d5e793275c34ca2aa336 100644 (file)
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -447,11 +447,9 @@ int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap)
 {
        unsigned long start_pfn = PFN_DOWN(start);
        unsigned long nr_pages = size >> PAGE_SHIFT;
-       struct zone *zone;
        int ret;
 
-       zone = page_zone(pfn_to_page(start_pfn));
-       ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
+       ret = remove_sections(nid, start_pfn, nr_pages, altmap);
        if (unlikely(ret))
                pr_warn("%s: Failed, __remove_pages() == %d\n", __func__,
                        ret);

diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 85c94f9a87f8c6247ddb0f645f69fee610cd1fe5..0b8c7b0033d2462a388f86b6aa79f11b2128f929 100644 (file)
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -866,8 +866,7 @@ int arch_remove_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap)
        unsigned long nr_pages = size >> PAGE_SHIFT;
        struct zone *zone;
 
-       zone = page_zone(pfn_to_page(start_pfn));
-       return __remove_pages(zone, start_pfn, nr_pages, altmap);
+       return remove_sections(nid, start_pfn, nr_pages, altmap);
 }
 #endif
 #endif

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 449958da97a49802dafe1d3306e25641cec6e9fc..f80d98381a979ec7798e48a03def8e06a61fd9af 100644 (file)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1152,15 +1152,9 @@ int __ref arch_remove_memory(int nid, u64 start, u64 size,
 {
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
-       struct page *page = pfn_to_page(start_pfn);
-       struct zone *zone;
        int ret;
 
-       /* With altmap the first mapped page is offset from @start */
-       if (altmap)
-               page += vmem_altmap_offset(altmap);
-       zone = page_zone(page);
-       ret = __remove_pages(zone, start_pfn, nr_pages, altmap);
+       ret = remove_sections(nid, start_pfn, nr_pages, altmap);
        WARN_ON_ONCE(ret);
        kernel_physical_mapping_remove(start, start + size);
 

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 9e4d9b9b93ea768592997e117718774155d31c9e..a5144ee932b4841b30c3f494a475294bdf5f3d54 100644 (file)
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -109,8 +109,10 @@ static inline bool movable_node_is_enabled(void)
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern int arch_remove_memory(int nid, u64 start, u64 size,
                                struct vmem_altmap *altmap);
-extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
-       unsigned long nr_pages, struct vmem_altmap *altmap);
+extern int remove_sections(int nid, unsigned long start_pfn,
+                       unsigned long nr_pages, struct vmem_altmap *altmap);
+extern void shrink_zone(struct zone *zone, unsigned long start_pfn,
+                       unsigned long end_pfn, unsigned long offlined_pages);
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 /* reasonably generic interface to expand the physical pages */
@@ -335,7 +337,7 @@ extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
 extern bool is_memblock_offlined(struct memory_block *mem);
 extern int sparse_add_one_section(struct pglist_data *pgdat,
                unsigned long start_pfn, struct vmem_altmap *altmap);
-extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
+extern void sparse_remove_one_section(int nid, struct mem_section *ms,
                unsigned long map_offset, struct vmem_altmap *altmap);
 extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
                                          unsigned long pnum);

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 0d5603d76c37859d496b2bf016cf04355ebd23ad..66cbf334203ba892aaf3e4cc1689abe24aab682b 100644 (file)
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -87,6 +87,7 @@ static void devm_memremap_pages_release(void *data)
        struct resource *res = &pgmap->res;
        resource_size_t align_start, align_size;
        unsigned long pfn;
+       unsigned long nr_pages;
        int nid;
 
        pgmap->kill(pgmap->ref);
@@ -101,10 +102,14 @@ static void devm_memremap_pages_release(void *data)
        nid = page_to_nid(pfn_to_page(align_start >> PAGE_SHIFT));
 
        mem_hotplug_begin();
+
+       pfn = align_start >> PAGE_SHIFT;
+       nr_pages = align_size >> PAGE_SHIFT;
+       offline_mem_sections(pfn, pfn + nr_pages);
+       shrink_zone(page_zone(pfn_to_page(pfn)), pfn, pfn + nr_pages, nr_pages);
+
        if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-               pfn = align_start >> PAGE_SHIFT;
-               __remove_pages(page_zone(pfn_to_page(pfn)), pfn,
-                               align_size >> PAGE_SHIFT, NULL);
+               remove_sections(nid, pfn, nr_pages, NULL);
        } else {
                arch_remove_memory(nid, align_start, align_size,
                                pgmap->altmap_valid ? &pgmap->altmap : NULL);
@@ -224,7 +229,10 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 
        if (!error) {
                struct zone *zone;
+               unsigned long pfn = align_start >> PAGE_SHIFT;
+               unsigned long nr_pages = align_size >> PAGE_SHIFT;
 
+               online_mem_sections(pfn, pfn + nr_pages);
                zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
                move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT,
                                align_size >> PAGE_SHIFT, altmap);

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 70816fdd7419e586d7b2f517a02eb4f5a23168c2..372a4f29710a6c604e42e3fe2941da4fe77c0434 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -314,6 +314,17 @@ out:
 }
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
+static bool is_section_ok(struct mem_section *ms, bool zone)
+{
+       /*
+        * We cannot shrink pgdat's spanned because we use them
+        * in try_offline_node to check if all sections were removed.
+        */
+       if (zone)
+               return online_section(ms);
+       else
+               return valid_section(ms);
+}
 /* find the smallest valid pfn in the range [start_pfn, end_pfn) */
 static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
                                     unsigned long start_pfn,
@@ -324,7 +335,7 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
        for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) {
                ms = __pfn_to_section(start_pfn);
 
-               if (unlikely(!valid_section(ms)))
+               if (!is_section_ok(ms, !!zone))
                        continue;
 
                if (unlikely(pfn_to_nid(start_pfn) != nid))
@@ -352,7 +363,7 @@ static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
        for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) {
                ms = __pfn_to_section(pfn);
 
-               if (unlikely(!valid_section(ms)))
+               if (!is_section_ok(ms, !!zone))
                        continue;
 
                if (unlikely(pfn_to_nid(pfn) != nid))
@@ -414,7 +425,7 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
        for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
                ms = __pfn_to_section(pfn);
 
-               if (unlikely(!valid_section(ms)))
+               if (unlikely(!online_section(ms)))
                        continue;
 
                if (page_zone(pfn_to_page(pfn)) != zone)
@@ -501,23 +512,33 @@ static void shrink_pgdat_span(struct pglist_data *pgdat,
        pgdat->node_spanned_pages = 0;
 }
 
-static void __remove_zone(struct zone *zone, unsigned long start_pfn)
+void shrink_zone(struct zone *zone, unsigned long start_pfn,
+               unsigned long end_pfn, unsigned long offlined_pages)
 {
-       struct pglist_data *pgdat = zone->zone_pgdat;
        int nr_pages = PAGES_PER_SECTION;
+       unsigned long pfn;
+
+       clear_zone_contiguous(zone);
+       for (pfn = start_pfn; pfn < end_pfn; pfn += nr_pages)
+               shrink_zone_span(zone, pfn, pfn + nr_pages);
+       set_zone_contiguous(zone);
+}
+
+static void shrink_pgdat(int nid, unsigned long sect_nr)
+{
+       struct pglist_data *pgdat = NODE_DATA(nid);
+       int nr_pages = PAGES_PER_SECTION;
+       unsigned long pfn = section_nr_to_pfn((unsigned long)sect_nr);
        unsigned long flags;
 
-       pgdat_resize_lock(zone->zone_pgdat, &flags);
-       shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
-       shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
-       pgdat_resize_unlock(zone->zone_pgdat, &flags);
+       pgdat_resize_lock(pgdat, &flags);
+       shrink_pgdat_span(pgdat, pfn, pfn + nr_pages);
+       pgdat_resize_unlock(pgdat, &flags);
 }
 
-static int __remove_section(struct zone *zone, struct mem_section *ms,
+static int __remove_section(int nid, struct mem_section *ms,
                unsigned long map_offset, struct vmem_altmap *altmap)
 {
-       unsigned long start_pfn;
-       int scn_nr;
        int ret = -EINVAL;
 
        if (!valid_section(ms))
@@ -527,17 +548,15 @@ static int __remove_section(struct zone *zone, struct mem_section *ms,
        if (ret)
                return ret;
 
-       scn_nr = __section_nr(ms);
-       start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
-       __remove_zone(zone, start_pfn);
+       shrink_pgdat(nid, __section_nr(ms));
 
-       sparse_remove_one_section(zone, ms, map_offset, altmap);
+       sparse_remove_one_section(nid, ms, map_offset, altmap);
        return 0;
 }
 
 /**
- * __remove_pages() - remove sections of pages from a zone
- * @zone: zone from which pages need to be removed
+ * __remove_pages() - remove sections of pages from a nid
+ * @nid: nid from which pages belong to
  * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
  * @nr_pages: number of pages to remove (must be multiple of section size)
  * @altmap: alternative device page map or %NULL if default memmap is used
@@ -547,35 +566,28 @@ static int __remove_section(struct zone *zone, struct mem_section *ms,
  * sure that pages are marked reserved and zones are adjust properly by
  * calling offline_pages().
  */
-int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
+int remove_sections(int nid, unsigned long phys_start_pfn,
                 unsigned long nr_pages, struct vmem_altmap *altmap)
 {
        unsigned long i;
        unsigned long map_offset = 0;
        int sections_to_remove, ret = 0;
+       resource_size_t start, size;
 
-       /* In the ZONE_DEVICE case device driver owns the memory region */
-       if (is_dev_zone(zone)) {
-               if (altmap)
-                       map_offset = vmem_altmap_offset(altmap);
-       } else {
-               resource_size_t start, size;
-
-               start = phys_start_pfn << PAGE_SHIFT;
-               size = nr_pages * PAGE_SIZE;
+       start = phys_start_pfn << PAGE_SHIFT;
+       size = nr_pages * PAGE_SIZE;
 
-               ret = release_mem_region_adjustable(&iomem_resource, start,
-                                       size);
-               if (ret) {
-                       resource_size_t endres = start + size - 1;
+       if (altmap)
+               map_offset = vmem_altmap_offset(altmap);
 
-                       pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
-                                       &start, &endres, ret);
-               }
+       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);
        }
 
-       clear_zone_contiguous(zone);
-
        /*
         * We can only remove entire sections
         */
@@ -587,15 +599,13 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
                unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
 
                cond_resched();
-               ret = __remove_section(zone, __pfn_to_section(pfn), map_offset,
-                               altmap);
+               ret = __remove_section(nid, __pfn_to_section(pfn), map_offset,
+                                                                       altmap);
                map_offset = 0;
                if (ret)
                        break;
        }
 
-       set_zone_contiguous(zone);
-
        return ret;
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */
@@ -1634,11 +1644,14 @@ repeat:
        /* reset pagetype flags and makes migrate type to be MOVABLE */
        undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
        /* removal success */
+
+       /* Shrink zone's managed,spanned and zone/pgdat's present pages */
        adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
        zone->present_pages -= offlined_pages;
 
        pgdat_resize_lock(zone->zone_pgdat, &flags);
        zone->zone_pgdat->node_present_pages -= offlined_pages;
+       shrink_zone(zone, valid_start, valid_end, offlined_pages);
        pgdat_resize_unlock(zone->zone_pgdat, &flags);
 
        init_per_zone_wmark_min();

diff --git a/mm/sparse.c b/mm/sparse.c
index b6ed029a2f46d435400be49d383dc7cf0e9cb886..25e02a41e3e001bd09e3dc36d7ecf8abb4813299 100644 (file)
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -774,12 +774,12 @@ static void free_section_usemap(struct page *memmap, unsigned long *usemap,
                free_map_bootmem(memmap);
 }
 
-void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
+void sparse_remove_one_section(int nid, struct mem_section *ms,
                unsigned long map_offset, struct vmem_altmap *altmap)
 {
        struct page *memmap = NULL;
        unsigned long *usemap = NULL, flags;
-       struct pglist_data *pgdat = zone->zone_pgdat;
+       struct pglist_data *pgdat = NODE_DATA(nid);
 
        pgdat_resize_lock(pgdat, &flags);
        if (ms->section_mem_map) {