path: root/mm
diff options
authorBaoquan He <bhe@redhat.com>2020-03-21 18:22:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-03-21 18:56:06 -0700
commitd41e2f3bd54699f85b3d6f45abd09fa24a222cb9 (patch)
treee7482951a78ce284f1fdbf59ed78e550255d0ae3 /mm
parentmemcg: fix NULL pointer dereference in __mem_cgroup_usage_unregister_event (diff)
mm/hotplug: fix hot remove failure in SPARSEMEM|!VMEMMAP case
In section_deactivate(), pfn_to_page() doesn't work any more after ms->section_mem_map is resetting to NULL in SPARSEMEM|!VMEMMAP case. It causes a hot remove failure: kernel BUG at mm/page_alloc.c:4806! invalid opcode: 0000 [#1] SMP PTI CPU: 3 PID: 8 Comm: kworker/u16:0 Tainted: G W 5.5.0-next-20200205+ #340 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 Workqueue: kacpi_hotplug acpi_hotplug_work_fn RIP: 0010:free_pages+0x85/0xa0 Call Trace: __remove_pages+0x99/0xc0 arch_remove_memory+0x23/0x4d try_remove_memory+0xc8/0x130 __remove_memory+0xa/0x11 acpi_memory_device_remove+0x72/0x100 acpi_bus_trim+0x55/0x90 acpi_device_hotplug+0x2eb/0x3d0 acpi_hotplug_work_fn+0x1a/0x30 process_one_work+0x1a7/0x370 worker_thread+0x30/0x380 kthread+0x112/0x130 ret_from_fork+0x35/0x40 Let's move the ->section_mem_map resetting after depopulate_section_memmap() to fix it. [akpm@linux-foundation.org: remove unneeded initialization, per David] Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug") Signed-off-by: Baoquan He <bhe@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Wei Yang <richardw.yang@linux.intel.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: <stable@vger.kernel.org> Link: http://lkml.kernel.org/r/20200307084229.28251-2-bhe@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 6 insertions, 2 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index 596b2a45b100..aadb7298dcef 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -734,6 +734,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
struct mem_section *ms = __pfn_to_section(pfn);
bool section_is_early = early_section(ms);
struct page *memmap = NULL;
+ bool empty;
unsigned long *subsection_map = ms->usage
? &ms->usage->subsection_map[0] : NULL;
@@ -764,7 +765,8 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
* For 2/ and 3/ the SPARSEMEM_VMEMMAP={y,n} cases are unified
bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
- if (bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION)) {
+ empty = bitmap_empty(subsection_map, SUBSECTIONS_PER_SECTION);
+ if (empty) {
unsigned long section_nr = pfn_to_section_nr(pfn);
@@ -779,13 +781,15 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
ms->usage = NULL;
memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
- ms->section_mem_map = (unsigned long)NULL;
if (section_is_early && memmap)
depopulate_section_memmap(pfn, nr_pages, altmap);
+ if (empty)
+ ms->section_mem_map = (unsigned long)NULL;
static struct page * __meminit section_activate(int nid, unsigned long pfn,