We currently try to shrink a single zone when removing memory. We use
the zone of the first page of the memory we are removing. If that
memmap was never initialized (e.g., memory was never onlined), we will
read garbage and can trigger kernel BUGs (due to a stale pointer):
BUG: unable to handle page fault for address: 000000000000353d
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] SMP PTI
CPU: 1 PID: 7 Comm: kworker/u8:0 Not tainted 5.3.0-rc5-next-20190820+ #317
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.4
Workqueue: kacpi_hotplug acpi_hotplug_work_fn
RIP: 0010:clear_zone_contiguous+0x5/0x10
Code: 48 89 c6 48 89 c3 e8 2a fe ff ff 48 85 c0 75 cf 5b 5d c3 c6 85 fd 05 00 00 01 5b 5d c3 0f 1f 840
RSP: 0018:ffffad2400043c98 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000200000000 RCX: 0000000000000000
RDX: 0000000000200000 RSI: 0000000000140000 RDI: 0000000000002f40
RBP: 0000000140000000 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000140000
R13: 0000000000140000 R14: 0000000000002f40 R15: ffff9e3e7aff3680
FS: 0000000000000000(0000) GS:ffff9e3e7bb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000353d CR3: 0000000058610000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__remove_pages+0x4b/0x640
arch_remove_memory+0x63/0x8d
try_remove_memory+0xdb/0x130
__remove_memory+0xa/0x11
acpi_memory_device_remove+0x70/0x100
acpi_bus_trim+0x55/0x90
acpi_device_hotplug+0x227/0x3a0
acpi_hotplug_work_fn+0x1a/0x30
process_one_work+0x221/0x550
worker_thread+0x50/0x3b0
kthread+0x105/0x140
ret_from_fork+0x3a/0x50
Modules linked in:
CR2: 000000000000353d
Instead, shrink the zones when offlining memory or when onlining failed.
Introduce and use remove_pfn_range_from_zone(() for that. We now
properly shrink the zones, even if we have DIMMs whereby
- Some memory blocks fall into no zone (never onlined)
- Some memory blocks fall into multiple zones (offlined+re-onlined)
- Multiple memory blocks that fall into different zones
Drop the zone parameter (with a potential dubious value) from
__remove_pages() and __remove_section().
Link: http://lkml.kernel.org/r/20191006085646.5768-6-david@redhat.com
Fixes: f1dd2cd13c ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [visible after d0dc12e86b]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: <stable@vger.kernel.org> [5.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The libnvdimm sub-system has suffered a series of hacks and broken
workarounds for the memory-hotplug implementation's awkward
section-aligned (128MB) granularity.
For example the following backtrace is emitted when attempting
arch_add_memory() with physical address ranges that intersect 'System
RAM' (RAM) with 'Persistent Memory' (PMEM) within a given section:
# cat /proc/iomem | grep -A1 -B1 Persistent\ Memory
100000000-1ffffffff : System RAM
200000000-303ffffff : Persistent Memory (legacy)
304000000-43fffffff : System RAM
440000000-23ffffffff : Persistent Memory
2400000000-43bfffffff : Persistent Memory
2400000000-43bfffffff : namespace2.0
WARNING: CPU: 38 PID: 928 at arch/x86/mm/init_64.c:850 add_pages+0x5c/0x60
[..]
RIP: 0010:add_pages+0x5c/0x60
[..]
Call Trace:
devm_memremap_pages+0x460/0x6e0
pmem_attach_disk+0x29e/0x680 [nd_pmem]
? nd_dax_probe+0xfc/0x120 [libnvdimm]
nvdimm_bus_probe+0x66/0x160 [libnvdimm]
It was discovered that the problem goes beyond RAM vs PMEM collisions as
some platform produce PMEM vs PMEM collisions within a given section.
The libnvdimm workaround for that case revealed that the libnvdimm
section-alignment-padding implementation has been broken for a long
while.
A fix for that long-standing breakage introduces as many problems as it
solves as it would require a backward-incompatible change to the
namespace metadata interpretation. Instead of that dubious route [1],
address the root problem in the memory-hotplug implementation.
Note that EEXIST is no longer treated as success as that is how
sparse_add_section() reports subsection collisions, it was also obviated
by recent changes to perform the request_region() for 'System RAM'
before arch_add_memory() in the add_memory() sequence.
[1] https://lore.kernel.org/r/155000671719.348031.2347363160141119237.stgit@dwillia2-desk3.amr.corp.intel.com
[osalvador@suse.de: fix deactivate_section for early sections]
Link: http://lkml.kernel.org/r/20190715081549.32577-2-osalvador@suse.de
Link: http://lkml.kernel.org/r/156092354368.979959.6232443923440952359.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [ppc64]
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch_add_memory, __add_pages take a want_memblock which controls whether
the newly added memory should get the sysfs memblock user API (e.g.
ZONE_DEVICE users do not want/need this interface). Some callers even
want to control where do we allocate the memmap from by configuring
altmap.
Add a more generic hotplug context for arch_add_memory and __add_pages.
struct mhp_restrictions contains flags which contains additional features
to be enabled by the memory hotplug (MHP_MEMBLOCK_API currently) and
altmap for alternative memmap allocator.
This patch shouldn't introduce any functional change.
[akpm@linux-foundation.org: build fix]
Link: http://lkml.kernel.org/r/20190408082633.2864-3-osalvador@suse.de
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
check_pages_isolated_cb currently accounts the whole pfn range as being
offlined if test_pages_isolated suceeds on the range. This is based on
the assumption that all pages in the range are freed which is currently
the case in most cases but it won't be with later changes, as pages marked
as vmemmap won't be isolated.
Move the offlined pages counting to offline_isolated_pages_cb and rely on
__offline_isolated_pages to return the correct value.
check_pages_isolated_cb will still do it's primary job and check the pfn
range.
While we are at it remove check_pages_isolated and offline_isolated_pages
and use directly walk_system_ram_range as do in online_pages.
Link: http://lkml.kernel.org/r/20190408082633.2864-2-osalvador@suse.de
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull xen updates from Juergen Gross:
"xen fixes and features:
- remove fallback code for very old Xen hypervisors
- three patches for fixing Xen dom0 boot regressions
- an old patch for Xen PCI passthrough which was never applied for
unknown reasons
- some more minor fixes and cleanup patches"
* tag 'for-linus-5.1a-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: fix dom0 boot on huge systems
xen, cpu_hotplug: Prevent an out of bounds access
xen: remove pre-xen3 fallback handlers
xen/ACPI: Switch to bitmap_zalloc()
x86/xen: dont add memory above max allowed allocation
x86: respect memory size limiting via mem= parameter
xen/gntdev: Check and release imported dma-bufs on close
xen/gntdev: Do not destroy context while dma-bufs are in use
xen/pciback: Don't disable PCI_COMMAND on PCI device reset.
xen-scsiback: mark expected switch fall-through
xen: mark expected switch fall-through
When limiting memory size via kernel parameter "mem=" this should be
respected even in case of memory made accessible via a PCI card.
Today this kind of memory won't be made usable in initial memory
setup as the memory won't be visible in E820 map, but it might be
added when adding PCI devices due to corresponding ACPI table entries.
Not respecting "mem=" can be corrected by adding a global max_mem_size
variable set by parse_memopt() which will result in rejecting adding
memory areas resulting in a memory size above the allowed limit.
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
On an arm64 ThunderX2 server, the first kmemleak scan would crash [1]
with CONFIG_DEBUG_VM_PGFLAGS=y due to page_to_nid() found a pfn that is
not directly mapped (MEMBLOCK_NOMAP). Hence, the page->flags is
uninitialized.
This is due to the commit 9f1eb38e0e ("mm, kmemleak: little
optimization while scanning") starts to use pfn_to_online_page() instead
of pfn_valid(). However, in the CONFIG_MEMORY_HOTPLUG=y case,
pfn_to_online_page() does not call memblock_is_map_memory() while
pfn_valid() does.
Historically, the commit 68709f4538 ("arm64: only consider memblocks
with NOMAP cleared for linear mapping") causes pages marked as nomap
being no long reassigned to the new zone in memmap_init_zone() by
calling __init_single_page().
Since the commit 2d070eab2e ("mm: consider zone which is not fully
populated to have holes") introduced pfn_to_online_page() and was
designed to return a valid pfn only, but it is clearly broken on arm64.
Therefore, let pfn_to_online_page() call pfn_valid_within(), so it can
handle nomap thanks to the commit f52bb98f5a ("arm64: mm: always
enable CONFIG_HOLES_IN_ZONE"), while it will be optimized away on
architectures where have no HOLES_IN_ZONE.
[1]
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000006
Mem abort info:
ESR = 0x96000005
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000005
CM = 0, WnR = 0
Internal error: Oops: 96000005 [#1] SMP
CPU: 60 PID: 1408 Comm: kmemleak Not tainted 5.0.0-rc2+ #8
pstate: 60400009 (nZCv daif +PAN -UAO)
pc : page_mapping+0x24/0x144
lr : __dump_page+0x34/0x3dc
sp : ffff00003a5cfd10
x29: ffff00003a5cfd10 x28: 000000000000802f
x27: 0000000000000000 x26: 0000000000277d00
x25: ffff000010791f56 x24: ffff7fe000000000
x23: ffff000010772f8b x22: ffff00001125f670
x21: ffff000011311000 x20: ffff000010772f8b
x19: fffffffffffffffe x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000
x15: 0000000000000000 x14: ffff802698b19600
x13: ffff802698b1a200 x12: ffff802698b16f00
x11: ffff802698b1a400 x10: 0000000000001400
x9 : 0000000000000001 x8 : ffff00001121a000
x7 : 0000000000000000 x6 : ffff0000102c53b8
x5 : 0000000000000000 x4 : 0000000000000003
x3 : 0000000000000100 x2 : 0000000000000000
x1 : ffff000010772f8b x0 : ffffffffffffffff
Process kmemleak (pid: 1408, stack limit = 0x(____ptrval____))
Call trace:
page_mapping+0x24/0x144
__dump_page+0x34/0x3dc
dump_page+0x28/0x4c
kmemleak_scan+0x4ac/0x680
kmemleak_scan_thread+0xb4/0xdc
kthread+0x12c/0x13c
ret_from_fork+0x10/0x18
Code: d503201f f9400660 36000040 d1000413 (f9400661)
---[ end trace 4d4bd7f573490c8e ]---
Kernel panic - not syncing: Fatal exception
SMP: stopping secondary CPUs
Kernel Offset: disabled
CPU features: 0x002,20000c38
Memory Limit: none
---[ end Kernel panic - not syncing: Fatal exception ]---
Link: http://lkml.kernel.org/r/20190122132916.28360-1-cai@lca.pw
Fixes: 9f1eb38e0e ("mm, kmemleak: little optimization while scanning")
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
