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commit c4dc63f0032c77464fbd4e7a6afc22fa6913c4a7 upstream.
In kdump kernel of x86_64, page allocation failure is observed:
kworker/u2:2: page allocation failure: order:0, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 0 PID: 55 Comm: kworker/u2:2 Not tainted 5.16.0-rc4+ #5
Hardware name: AMD Dinar/Dinar, BIOS RDN1505B 06/05/2013
Workqueue: events_unbound async_run_entry_fn
Call Trace:
<TASK>
dump_stack_lvl+0x48/0x5e
warn_alloc.cold+0x72/0xd6
__alloc_pages_slowpath.constprop.0+0xc69/0xcd0
__alloc_pages+0x1df/0x210
new_slab+0x389/0x4d0
___slab_alloc+0x58f/0x770
__slab_alloc.constprop.0+0x4a/0x80
kmem_cache_alloc_trace+0x24b/0x2c0
sr_probe+0x1db/0x620
......
device_add+0x405/0x920
......
__scsi_add_device+0xe5/0x100
ata_scsi_scan_host+0x97/0x1d0
async_run_entry_fn+0x30/0x130
process_one_work+0x1e8/0x3c0
worker_thread+0x50/0x3b0
? rescuer_thread+0x350/0x350
kthread+0x16b/0x190
? set_kthread_struct+0x40/0x40
ret_from_fork+0x22/0x30
</TASK>
Mem-Info:
......
The above failure happened when calling kmalloc() to allocate buffer with
GFP_DMA. It requests to allocate slab page from DMA zone while no managed
pages at all in there.
sr_probe()
--> get_capabilities()
--> buffer = kmalloc(512, GFP_KERNEL | GFP_DMA);
Because in the current kernel, dma-kmalloc will be created as long as
CONFIG_ZONE_DMA is enabled. However, kdump kernel of x86_64 doesn't have
managed pages on DMA zone since commit 6f599d84231f ("x86/kdump: Always
reserve the low 1M when the crashkernel option is specified"). The
failure can be always reproduced.
For now, let's mute the warning of allocation failure if requesting pages
from DMA zone while no managed pages.
[akpm@linux-foundation.org: fix warning]
Link: https://lkml.kernel.org/r/20211223094435.248523-4-bhe@redhat.com
Fixes: 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 62b3107073646e0946bd97ff926832bafb846d17 upstream.
Patch series "Handle warning of allocation failure on DMA zone w/o
managed pages", v4.
**Problem observed:
On x86_64, when crash is triggered and entering into kdump kernel, page
allocation failure can always be seen.
---------------------------------
DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
swapper/0: page allocation failure: order:5, mode:0xcc1(GFP_KERNEL|GFP_DMA), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 0 PID: 1 Comm: swapper/0
Call Trace:
dump_stack+0x7f/0xa1
warn_alloc.cold+0x72/0xd6
......
__alloc_pages+0x24d/0x2c0
......
dma_atomic_pool_init+0xdb/0x176
do_one_initcall+0x67/0x320
? rcu_read_lock_sched_held+0x3f/0x80
kernel_init_freeable+0x290/0x2dc
? rest_init+0x24f/0x24f
kernel_init+0xa/0x111
ret_from_fork+0x22/0x30
Mem-Info:
------------------------------------
***Root cause:
In the current kernel, it assumes that DMA zone must have managed pages
and try to request pages if CONFIG_ZONE_DMA is enabled. While this is not
always true. E.g in kdump kernel of x86_64, only low 1M is presented and
locked down at very early stage of boot, so that this low 1M won't be
added into buddy allocator to become managed pages of DMA zone. This
exception will always cause page allocation failure if page is requested
from DMA zone.
***Investigation:
This failure happens since below commit merged into linus's tree.
1a6a9044b967 x86/setup: Remove CONFIG_X86_RESERVE_LOW and reservelow= options
23721c8e92f7 x86/crash: Remove crash_reserve_low_1M()
f1d4d47c5851 x86/setup: Always reserve the first 1M of RAM
7c321eb2b843 x86/kdump: Remove the backup region handling
6f599d84231f x86/kdump: Always reserve the low 1M when the crashkernel option is specified
Before them, on x86_64, the low 640K area will be reused by kdump kernel.
So in kdump kernel, the content of low 640K area is copied into a backup
region for dumping before jumping into kdump. Then except of those firmware
reserved region in [0, 640K], the left area will be added into buddy
allocator to become available managed pages of DMA zone.
However, after above commits applied, in kdump kernel of x86_64, the low
1M is reserved by memblock, but not released to buddy allocator. So any
later page allocation requested from DMA zone will fail.
At the beginning, if crashkernel is reserved, the low 1M need be locked
down because AMD SME encrypts memory making the old backup region
mechanims impossible when switching into kdump kernel.
Later, it was also observed that there are BIOSes corrupting memory
under 1M. To solve this, in commit f1d4d47c5851, the entire region of
low 1M is always reserved after the real mode trampoline is allocated.
Besides, recently, Intel engineer mentioned their TDX (Trusted domain
extensions) which is under development in kernel also needs to lock down
the low 1M. So we can't simply revert above commits to fix the page allocation
failure from DMA zone as someone suggested.
***Solution:
Currently, only DMA atomic pool and dma-kmalloc will initialize and
request page allocation with GFP_DMA during bootup.
So only initializ DMA atomic pool when DMA zone has available managed
pages, otherwise just skip the initialization.
For dma-kmalloc(), for the time being, let's mute the warning of
allocation failure if requesting pages from DMA zone while no manged
pages. Meanwhile, change code to use dma_alloc_xx/dma_map_xx API to
replace kmalloc(GFP_DMA), or do not use GFP_DMA when calling kmalloc() if
not necessary. Christoph is posting patches to fix those under
drivers/scsi/. Finally, we can remove the need of dma-kmalloc() as people
suggested.
This patch (of 3):
In some places of the current kernel, it assumes that dma zone must have
managed pages if CONFIG_ZONE_DMA is enabled. While this is not always
true. E.g in kdump kernel of x86_64, only low 1M is presented and locked
down at very early stage of boot, so that there's no managed pages at all
in DMA zone. This exception will always cause page allocation failure if
page is requested from DMA zone.
Here add function has_managed_dma() and the relevant helper functions to
check if there's DMA zone with managed pages. It will be used in later
patches.
Link: https://lkml.kernel.org/r/20211223094435.248523-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20211223094435.248523-2-bhe@redhat.com
Fixes: 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified")
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: John Donnelly <john.p.donnelly@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7ad69832f37e3cea8557db6df7c793905f1135e8 upstream.
When we free a page whose order is very close to MAX_ORDER and greater
than pageblock_order, it wastes some CPU cycles to increase max_order to
MAX_ORDER one by one and check the pageblock migratetype of that page
repeatedly especially when MAX_ORDER is much larger than pageblock_order.
We also should not be checking migratetype of buddy when "order ==
MAX_ORDER - 1" as the buddy pfn may be invalid, so adjust the condition.
With the new check, we don't need the max_order check anymore, so we
replace it.
Also adjust max_order initialization so that it's lower by one than
previously, which makes the code hopefully more clear.
Link: https://lkml.kernel.org/r/20201204155109.55451-1-songmuchun@bytedance.com
Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 122e093c1734361dedb64f65c99b93e28e4624f4 upstream.
On systems with memory nodes sorted in descending order, for instance Dell
Precision WorkStation T5500, the struct pages for higher PFNs and
respectively lower nodes, could be overwritten by the initialization of
struct pages corresponding to the holes in the memory sections.
For example for the below memory layout
[ 0.245624] Early memory node ranges
[ 0.248496] node 1: [mem 0x0000000000001000-0x0000000000090fff]
[ 0.251376] node 1: [mem 0x0000000000100000-0x00000000dbdf8fff]
[ 0.254256] node 1: [mem 0x0000000100000000-0x0000001423ffffff]
[ 0.257144] node 0: [mem 0x0000001424000000-0x0000002023ffffff]
the range 0x1424000000 - 0x1428000000 in the beginning of node 0 starts in
the middle of a section and will be considered as a hole during the
initialization of the last section in node 1.
The wrong initialization of the memory map causes panic on boot when
CONFIG_DEBUG_VM is enabled.
Reorder loop order of the memory map initialization so that the outer loop
will always iterate over populated memory regions in the ascending order
and the inner loop will select the zone corresponding to the PFN range.
This way initialization of the struct pages for the memory holes will be
always done for the ranges that are actually not populated.
[akpm@linux-foundation.org: coding style fixes]
Link: https://lkml.kernel.org/r/YNXlMqBbL+tBG7yq@kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=213073
Link: https://lkml.kernel.org/r/20210624062305.10940-1-rppt@kernel.org
Fixes: 0740a50b9baa ("mm/page_alloc.c: refactor initialization of struct page for holes in memory layout")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Boris Petkov <bp@alien8.de>
Cc: Robert Shteynfeld <robert.shteynfeld@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[rppt: tweak for compatibility with IA64's override of memmap_init]
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit f7ec104458e00d27a190348ac3a513f3df3699a4 ]
commit f63661566fad ("mm/page_alloc.c: clear out zone->lowmem_reserve[] if
the zone is empty") clears out zone->lowmem_reserve[] if zone is empty.
But when zone is not empty and sysctl_lowmem_reserve_ratio[i] is set to
zero, zone_managed_pages(zone) is not counted in the managed_pages either.
This is inconsistent with the description of lowmem_reserve, so fix it.
Link: https://lkml.kernel.org/r/20210527125707.3760259-1-liushixin2@huawei.com
Fixes: f63661566fad ("mm/page_alloc.c: clear out zone->lowmem_reserve[] if the zone is empty")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reported-by: yangerkun <yangerkun@huawei.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 470c61d70299b1826f56ff5fede10786798e3c14 ]
setup_per_zone_lowmem_reserve() iterates through each zone setting
zone->lowmem_reserve[j] = 0 (where j is the zone's index) then iterates
backwards through all preceding zones, setting
lower_zone->lowmem_reserve[j] = sum(managed pages of higher zones) /
lowmem_reserve_ratio[idx] for each (where idx is the lower zone's index).
If the lower zone has no managed pages or its ratio is 0 then all of its
lowmem_reserve[] entries are effectively zeroed.
As these arrays are only assigned here and all lowmem_reserve[] entries
for index < this zone's index are implicitly assumed to be 0 (as these are
specifically output in show_free_areas() and zoneinfo_show_print() for
example) there is no need to additionally zero index == this zone's index
too. This patch avoids zeroing unnecessarily.
Rather than iterating through zones and setting lowmem_reserve[j] for each
lower zone this patch reverse the process and populates each zone's
lowmem_reserve[] values in ascending order.
This clarifies what is going on especially in the case of zero managed
pages or ratio which is now explicitly shown to clear these values.
Link: https://lkml.kernel.org/r/20201129162758.115907-1-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit bac9c6fa1f929213bbd0ac9cdf21e8e2f0916828 upstream.
Recently we found that there is a lot MemFree left in /proc/meminfo
after do a lot of pages soft offline, it's not quite correct.
Before Oscar's rework of soft offline for free pages [1], if we soft
offline free pages, these pages are left in buddy with HWPoison flag,
and NR_FREE_PAGES is not updated immediately. So the difference between
NR_FREE_PAGES and real number of available free pages is also even big
at the beginning.
However, with the workload running, when we catch HWPoison page in any
alloc functions subsequently, we will remove it from buddy, meanwhile
update the NR_FREE_PAGES and try again, so the NR_FREE_PAGES will get
more and more closer to the real number of available free pages.
(regardless of unpoison_memory())
Now, for offline free pages, after a successful call
take_page_off_buddy(), the page is no longer belong to buddy allocator,
and will not be used any more, but we missed accounting NR_FREE_PAGES in
this situation, and there is no chance to be updated later.
Do update in take_page_off_buddy() like rmqueue() does, but avoid double
counting if some one already set_migratetype_isolate() on the page.
[1]: commit 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages")
Link: https://lkml.kernel.org/r/20210526075247.11130-1-dinghui@sangfor.com.cn
Fixes: 06be6ff3d2ec ("mm,hwpoison: rework soft offline for free pages")
Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
Suggested-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e1baddf8475b06cc56f4bafecf9a32a124343d9f upstream.
As described in the split_page() comment, for the non-compound high order
page, the sub-pages must be freed individually. If the memcg of the first
page is valid, the tail pages cannot be uncharged when be freed.
For example, when alloc_pages_exact is used to allocate 1MB continuous
physical memory, 2MB is charged(kmemcg is enabled and __GFP_ACCOUNT is
set). When make_alloc_exact free the unused 1MB and free_pages_exact free
the applied 1MB, actually, only 4KB(one page) is uncharged.
Therefore, the memcg of the tail page needs to be set when splitting a
page.
Michel:
There are at least two explicit users of __GFP_ACCOUNT with
alloc_exact_pages added recently. See 7efe8ef274024 ("KVM: arm64:
Allocate stage-2 pgd pages with GFP_KERNEL_ACCOUNT") and c419621873713
("KVM: s390: Add memcg accounting to KVM allocations"), so this is not
just a theoretical issue.
Link: https://lkml.kernel.org/r/20210304074053.65527-3-zhouguanghui1@huawei.com
Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Rui Xiang <rui.xiang@huawei.com>
Cc: Tianhong Ding <dingtianhong@huawei.com>
Cc: Weilong Chen <chenweilong@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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layout
commit 0740a50b9baa4472cfb12442df4b39e2712a64a4 upstream.
There could be struct pages that are not backed by actual physical memory.
This can happen when the actual memory bank is not a multiple of
SECTION_SIZE or when an architecture does not register memory holes
reserved by the firmware as memblock.memory.
Such pages are currently initialized using init_unavailable_mem() function
that iterates through PFNs in holes in memblock.memory and if there is a
struct page corresponding to a PFN, the fields of this page are set to
default values and it is marked as Reserved.
init_unavailable_mem() does not take into account zone and node the page
belongs to and sets both zone and node links in struct page to zero.
Before commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock
regions rather that check each PFN") the holes inside a zone were
re-initialized during memmap_init() and got their zone/node links right.
However, after that commit nothing updates the struct pages representing
such holes.
On a system that has firmware reserved holes in a zone above ZONE_DMA, for
instance in a configuration below:
# grep -A1 E820 /proc/iomem
7a17b000-7a216fff : Unknown E820 type
7a217000-7bffffff : System RAM
unset zone link in struct page will trigger
VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
in set_pfnblock_flags_mask() when called with a struct page from a range
other than E820_TYPE_RAM because there are pages in the range of
ZONE_DMA32 but the unset zone link in struct page makes them appear as a
part of ZONE_DMA.
Interleave initialization of the unavailable pages with the normal
initialization of memory map, so that zone and node information will be
properly set on struct pages that are not backed by the actual memory.
With this change the pages for holes inside a zone will get proper
zone/node links and the pages that are not spanned by any node will get
links to the adjacent zone/node. The holes between nodes will be
prepended to the zone/node above the hole and the trailing pages in the
last section that will be appended to the zone/node below.
[akpm@linux-foundation.org: don't initialize static to zero, use %llu for u64]
Link: https://lkml.kernel.org/r/20210225224351.7356-2-rppt@kernel.org
Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: Qian Cai <cai@lca.pw>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Łukasz Majczak <lma@semihalf.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Sarvela, Tomi P" <tomi.p.sarvela@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ce8f86ee94fabcc98537ddccd7e82cfd360a4dc5 upstream.
The trace point *trace_mm_page_alloc_zone_locked()* in __rmqueue() does
not currently cover all branches. Add the missing tracepoint and check
the page before do that.
[akpm@linux-foundation.org: use IS_ENABLED() to suppress warning]
Link: https://lkml.kernel.org/r/20201228132901.41523-1-carver4lio@163.com
Signed-off-by: Hailong liu <liu.hailong6@zte.com.cn>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ivan Babrou <ivan@cloudflare.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 377bf660d07a47269510435d11f3b65d53edca20 upstream.
This reverts commit d3921cb8be29ce5668c64e23ffdaeec5f8c69399.
Chris Wilson reports that it causes boot problems:
"We have half a dozen or so different machines in CI that are silently
failing to boot, that we believe is bisected to this patch"
and the CI team confirmed that a revert fixed the issues.
The cause is unknown for now, so let's revert it.
Link: https://lore.kernel.org/lkml/161160687463.28991.354987542182281928@build.alporthouse.com/
Reported-and-tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d3921cb8be29ce5668c64e23ffdaeec5f8c69399 upstream.
There could be struct pages that are not backed by actual physical
memory. This can happen when the actual memory bank is not a multiple
of SECTION_SIZE or when an architecture does not register memory holes
reserved by the firmware as memblock.memory.
Such pages are currently initialized using init_unavailable_mem()
function that iterates through PFNs in holes in memblock.memory and if
there is a struct page corresponding to a PFN, the fields if this page
are set to default values and the page is marked as Reserved.
init_unavailable_mem() does not take into account zone and node the page
belongs to and sets both zone and node links in struct page to zero.
On a system that has firmware reserved holes in a zone above ZONE_DMA,
for instance in a configuration below:
# grep -A1 E820 /proc/iomem
7a17b000-7a216fff : Unknown E820 type
7a217000-7bffffff : System RAM
unset zone link in struct page will trigger
VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link
in struct page) in the same pageblock.
Update init_unavailable_mem() to use zone constraints defined by an
architecture to properly setup the zone link and use node ID of the
adjacent range in memblock.memory to set the node link.
Link: https://lkml.kernel.org/r/20210111194017.22696-3-rppt@kernel.org
Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit dc2da7b45ffe954a0090f5d0310ed7b0b37d2bd2 upstream.
VMware observed a performance regression during memmap init on their
platform, and bisected to commit 73a6e474cb376 ("mm: memmap_init:
iterate over memblock regions rather that check each PFN") causing it.
Before the commit:
[0.033176] Normal zone: 1445888 pages used for memmap
[0.033176] Normal zone: 89391104 pages, LIFO batch:63
[0.035851] ACPI: PM-Timer IO Port: 0x448
With commit
[0.026874] Normal zone: 1445888 pages used for memmap
[0.026875] Normal zone: 89391104 pages, LIFO batch:63
[2.028450] ACPI: PM-Timer IO Port: 0x448
The root cause is the current memmap defer init doesn't work as expected.
Before, memmap_init_zone() was used to do memmap init of one whole zone,
to initialize all low zones of one numa node, but defer memmap init of
the last zone in that numa node. However, since commit 73a6e474cb376,
function memmap_init() is adapted to iterater over memblock regions
inside one zone, then call memmap_init_zone() to do memmap init for each
region.
E.g, on VMware's system, the memory layout is as below, there are two
memory regions in node 2. The current code will mistakenly initialize the
whole 1st region [mem 0xab00000000-0xfcffffffff], then do memmap defer to
iniatialize only one memmory section on the 2nd region [mem
0x10000000000-0x1033fffffff]. In fact, we only expect to see that there's
only one memory section's memmap initialized. That's why more time is
costed at the time.
[ 0.008842] ACPI: SRAT: Node 0 PXM 0 [mem 0x00000000-0x0009ffff]
[ 0.008842] ACPI: SRAT: Node 0 PXM 0 [mem 0x00100000-0xbfffffff]
[ 0.008843] ACPI: SRAT: Node 0 PXM 0 [mem 0x100000000-0x55ffffffff]
[ 0.008844] ACPI: SRAT: Node 1 PXM 1 [mem 0x5600000000-0xaaffffffff]
[ 0.008844] ACPI: SRAT: Node 2 PXM 2 [mem 0xab00000000-0xfcffffffff]
[ 0.008845] ACPI: SRAT: Node 2 PXM 2 [mem 0x10000000000-0x1033fffffff]
Now, let's add a parameter 'zone_end_pfn' to memmap_init_zone() to pass
down the real zone end pfn so that defer_init() can use it to judge
whether defer need be taken in zone wide.
Link: https://lkml.kernel.org/r/20201223080811.16211-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20201223080811.16211-2-bhe@redhat.com
Fixes: commit 73a6e474cb376 ("mm: memmap_init: iterate over memblock regions rather that check each PFN")
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Rahul Gopakumar <gopakumarr@vmware.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 597c892038e08098b17ccfe65afd9677e6979800 ]
On 2-node NUMA hosts we see bursts of kswapd reclaim and subsequent
pressure spikes and stalls from cache refaults while there is plenty of
free memory in the system.
Usually, kswapd is woken up when all eligible nodes in an allocation are
full. But the code related to watermark boosting can wake kswapd on one
full node while the other one is mostly empty. This may be justified to
fight fragmentation, but is currently unconditionally done whether
watermark boosting is occurring or not.
In our case, many of our workloads' throughput scales with available
memory, and pure utilization is a more tangible concern than trends
around longer-term fragmentation. As a result we generally disable
watermark boosting.
Wake kswapd only woken when watermark boosting is requested.
Link: https://lkml.kernel.org/r/20201020175833.397286-1-hannes@cmpxchg.org
Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external fragmentation event occurs")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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The ethernet driver may allocate skb (and skb->data) via napi_alloc_skb().
This ends up to page_frag_alloc() to allocate skb->data from
page_frag_cache->va.
During the memory pressure, page_frag_cache->va may be allocated as
pfmemalloc page. As a result, the skb->pfmemalloc is always true as
skb->data is from page_frag_cache->va. The skb will be dropped if the
sock (receiver) does not have SOCK_MEMALLOC. This is expected behaviour
under memory pressure.
However, once kernel is not under memory pressure any longer (suppose large
amount of memory pages are just reclaimed), the page_frag_alloc() may still
re-use the prior pfmemalloc page_frag_cache->va to allocate skb->data. As a
result, the skb->pfmemalloc is always true unless page_frag_cache->va is
re-allocated, even if the kernel is not under memory pressure any longer.
Here is how kernel runs into issue.
1. The kernel is under memory pressure and allocation of
PAGE_FRAG_CACHE_MAX_ORDER in __page_frag_cache_refill() will fail. Instead,
the pfmemalloc page is allocated for page_frag_cache->va.
2: All skb->data from page_frag_cache->va (pfmemalloc) will have
skb->pfmemalloc=true. The skb will always be dropped by sock without
SOCK_MEMALLOC. This is an expected behaviour.
3. Suppose a large amount of pages are reclaimed and kernel is not under
memory pressure any longer. We expect skb->pfmemalloc drop will not happen.
4. Unfortunately, page_frag_alloc() does not proactively re-allocate
page_frag_alloc->va and will always re-use the prior pfmemalloc page. The
skb->pfmemalloc is always true even kernel is not under memory pressure any
longer.
Fix this by freeing and re-allocating the page instead of recycling it.
References: https://lore.kernel.org/lkml/20201103193239.1807-1-dongli.zhang@oracle.com/
References: https://lore.kernel.org/linux-mm/20201105042140.5253-1-willy@infradead.org/
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Cc: Bert Barbe <bert.barbe@oracle.com>
Cc: Rama Nichanamatlu <rama.nichanamatlu@oracle.com>
Cc: Venkat Venkatsubra <venkat.x.venkatsubra@oracle.com>
Cc: Manjunath Patil <manjunath.b.patil@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Cc: SRINIVAS <srinivas.eeda@oracle.com>
Fixes: 79930f5892e1 ("net: do not deplete pfmemalloc reserve")
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201115201029.11903-1-dongli.zhang@oracle.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge more updates from Andrew Morton:
"155 patches.
Subsystems affected by this patch series: mm (dax, debug, thp,
readahead, page-poison, util, memory-hotplug, zram, cleanups), misc,
core-kernel, get_maintainer, MAINTAINERS, lib, bitops, checkpatch,
binfmt, ramfs, autofs, nilfs, rapidio, panic, relay, kgdb, ubsan,
romfs, and fault-injection"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (155 commits)
lib, uaccess: add failure injection to usercopy functions
lib, include/linux: add usercopy failure capability
ROMFS: support inode blocks calculation
ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang
sched.h: drop in_ubsan field when UBSAN is in trap mode
scripts/gdb/tasks: add headers and improve spacing format
scripts/gdb/proc: add struct mount & struct super_block addr in lx-mounts command
kernel/relay.c: drop unneeded initialization
panic: dump registers on panic_on_warn
rapidio: fix the missed put_device() for rio_mport_add_riodev
rapidio: fix error handling path
nilfs2: fix some kernel-doc warnings for nilfs2
autofs: harden ioctl table
ramfs: fix nommu mmap with gaps in the page cache
mm: remove the now-unnecessary mmget_still_valid() hack
mm/gup: take mmap_lock in get_dump_page()
binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot
coredump: rework elf/elf_fdpic vma_dump_size() into common helper
coredump: refactor page range dumping into common helper
coredump: let dump_emit() bail out on short writes
...
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The current page_order() can only be called on pages in the buddy
allocator. For compound pages, you have to use compound_order(). This is
confusing and led to a bug, so rename page_order() to buddy_order().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20201001152259.14932-2-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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__free_pages_core() is used when exposing fresh memory to the buddy during
system boot and when onlining memory in generic_online_page().
generic_online_page() is used in two cases:
1. Direct memory onlining in online_pages().
2. Deferred memory onlining in memory-ballooning-like mechanisms (HyperV
balloon and virtio-mem), when parts of a section are kept
fake-offline to be fake-onlined later on.
In 1, we already place pages to the tail of the freelist. Pages will be
freed to MIGRATE_ISOLATE lists first and moved to the tail of the
freelists via undo_isolate_page_range().
In 2, we currently don't implement a proper rule. In case of virtio-mem,
where we currently always online MAX_ORDER - 1 pages, the pages will be
placed to the HEAD of the freelist - undesireable. While the hyper-v
balloon calls generic_online_page() with single pages, usually it will
call it on successive single pages in a larger block.
The pages are fresh, so place them to the tail of the freelist and avoid
the PCP. In __free_pages_core(), remove the now superflouos call to
set_page_refcounted() and add a comment regarding page initialization and
the refcount.
Note: In 2. we currently don't shuffle. If ever relevant (page shuffling
is usually of limited use in virtualized environments), we might want to
shuffle after a sequence of generic_online_page() calls in the relevant
callers.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Link: https://lkml.kernel.org/r/20201005121534.15649-5-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Whenever we move pages between freelists via move_to_free_list()/
move_freepages_block(), we don't actually touch the pages:
1. Page isolation doesn't actually touch the pages, it simply isolates
pageblocks and moves all free pages to the MIGRATE_ISOLATE freelist.
When undoing isolation, we move the pages back to the target list.
2. Page stealing (steal_suitable_fallback()) moves free pages directly
between lists without touching them.
3. reserve_highatomic_pageblock()/unreserve_highatomic_pageblock() moves
free pages directly between freelists without touching them.
We already place pages to the tail of the freelists when undoing isolation
via __putback_isolated_page(), let's do it in any case (e.g., if order <=
pageblock_order) and document the behavior. To simplify, let's move the
pages to the tail for all move_to_free_list()/move_freepages_block() users.
In 2., the target list is empty, so there should be no change. In 3., we
might observe a change, however, highatomic is more concerned about
allocations succeeding than cache hotness - if we ever realize this change
degrades a workload, we can special-case this instance and add a proper
comment.
This change results in all pages getting onlined via online_pages() to be
placed to the tail of the freelist.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Link: https://lkml.kernel.org/r/20201005121534.15649-4-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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__putback_isolated_page() already documents that pages will be placed to
the tail of the freelist - this is, however, not the case for "order >=
MAX_ORDER - 2" (see buddy_merge_likely()) - which should be the case for
all existing users.
This change affects two users:
- free page reporting
- page isolation, when undoing the isolation (including memory onlining).
This behavior is desirable for pages that haven't really been touched
lately, so exactly the two users that don't actually read/write page
content, but rather move untouched pages.
The new behavior is especially desirable for memory onlining, where we
allow allocation of newly onlined pages via undo_isolate_page_range() in
online_pages(). Right now, we always place them to the head of the
freelist, resulting in undesireable behavior: Assume we add individual
memory chunks via add_memory() and online them right away to the NORMAL
zone. We create a dependency chain of unmovable allocations e.g., via the
memmap. The memmap of the next chunk will be placed onto previous chunks
- if the last block cannot get offlined+removed, all dependent ones cannot
get offlined+removed. While this can already be observed with individual
DIMMs, it's more of an issue for virtio-mem (and I suspect also ppc
DLPAR).
Document that this should only be used for optimizations, and no code
should rely on this behavior for correction (if the order of the freelists
ever changes).
We won't care about page shuffling: memory onlining already properly
shuffles after onlining. free page reporting doesn't care about
physically contiguous ranges, and there are already cases where page
isolation will simply move (physically close) free pages to (currently)
the head of the freelists via move_freepages_block() instead of shuffling.
If this becomes ever relevant, we should shuffle the whole zone when
undoing isolation of larger ranges, and after free_contig_range().
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Link: https://lkml.kernel.org/r/20201005121534.15649-3-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Patch series "mm: place pages to the freelist tail when onlining and undoing isolation", v2.
When adding separate memory blocks via add_memory*() and onlining them
immediately, the metadata (especially the memmap) of the next block will
be placed onto one of the just added+onlined block. This creates a chain
of unmovable allocations: If the last memory block cannot get
offlined+removed() so will all dependent ones. We directly have unmovable
allocations all over the place.
This can be observed quite easily using virtio-mem, however, it can also
be observed when using DIMMs. The freshly onlined pages will usually be
placed to the head of the freelists, meaning they will be allocated next,
turning the just-added memory usually immediately un-removable. The fresh
pages are cold, prefering to allocate others (that might be hot) also
feels to be the natural thing to do.
It also applies to the hyper-v balloon xen-balloon, and ppc64 dlpar: when
adding separate, successive memory blocks, each memory block will have
unmovable allocations on them - for example gigantic pages will fail to
allocate.
While the ZONE_NORMAL doesn't provide any guarantees that memory can get
offlined+removed again (any kind of fragmentation with unmovable
allocations is possible), there are many scenarios (hotplugging a lot of
memory, running workload, hotunplug some memory/as much as possible) where
we can offline+remove quite a lot with this patchset.
a) To visualize the problem, a very simple example:
Start a VM with 4GB and 8GB of virtio-mem memory:
[root@localhost ~]# lsmem
RANGE SIZE STATE REMOVABLE BLOCK
0x0000000000000000-0x00000000bfffffff 3G online yes 0-23
0x0000000100000000-0x000000033fffffff 9G online yes 32-103
Memory block size: 128M
Total online memory: 12G
Total offline memory: 0B
Then try to unplug as much as possible using virtio-mem. Observe which
memory blocks are still around. Without this patch set:
[root@localhost ~]# lsmem
RANGE SIZE STATE REMOVABLE BLOCK
0x0000000000000000-0x00000000bfffffff 3G online yes 0-23
0x0000000100000000-0x000000013fffffff 1G online yes 32-39
0x0000000148000000-0x000000014fffffff 128M online yes 41
0x0000000158000000-0x000000015fffffff 128M online yes 43
0x0000000168000000-0x000000016fffffff 128M online yes 45
0x0000000178000000-0x000000017fffffff 128M online yes 47
0x0000000188000000-0x0000000197ffffff 256M online yes 49-50
0x00000001a0000000-0x00000001a7ffffff 128M online yes 52
0x00000001b0000000-0x00000001b7ffffff 128M online yes 54
0x00000001c0000000-0x00000001c7ffffff 128M online yes 56
0x00000001d0000000-0x00000001d7ffffff 128M online yes 58
0x00000001e0000000-0x00000001e7ffffff 128M online yes 60
0x00000001f0000000-0x00000001f7ffffff 128M online yes 62
0x0000000200000000-0x0000000207ffffff 128M online yes 64
0x0000000210000000-0x0000000217ffffff 128M online yes 66
0x0000000220000000-0x0000000227ffffff 128M online yes 68
0x0000000230000000-0x0000000237ffffff 128M online yes 70
0x0000000240000000-0x0000000247ffffff 128M online yes 72
0x0000000250000000-0x0000000257ffffff 128M online yes 74
0x0000000260000000-0x0000000267ffffff 128M online yes 76
0x0000000270000000-0x0000000277ffffff 128M online yes 78
0x0000000280000000-0x0000000287ffffff 128M online yes 80
0x0000000290000000-0x0000000297ffffff 128M online yes 82
0x00000002a0000000-0x00000002a7ffffff 128M online yes 84
0x00000002b0000000-0x00000002b7ffffff 128M online yes 86
0x00000002c0000000-0x00000002c7ffffff 128M online yes 88
0x00000002d0000000-0x00000002d7ffffff 128M online yes 90
0x00000002e0000000-0x00000002e7ffffff 128M online yes 92
0x00000002f0000000-0x00000002f7ffffff 128M online yes 94
0x0000000300000000-0x0000000307ffffff 128M online yes 96
0x0000000310000000-0x0000000317ffffff 128M online yes 98
0x0000000320000000-0x0000000327ffffff 128M online yes 100
0x0000000330000000-0x000000033fffffff 256M online yes 102-103
Memory block size: 128M
Total online memory: 8.1G
Total offline memory: 0B
With this patch set:
[root@localhost ~]# lsmem
RANGE SIZE STATE REMOVABLE BLOCK
0x0000000000000000-0x00000000bfffffff 3G online yes 0-23
0x0000000100000000-0x000000013fffffff 1G online yes 32-39
Memory block size: 128M
Total online memory: 4G
Total offline memory: 0B
All memory can get unplugged, all memory block can get removed. Of
course, no workload ran and the system was basically idle, but it
highlights the issue - the fairly deterministic chain of unmovable
allocations. When a huge page for the 2MB memmap is needed, a
just-onlined 4MB page will be split. The remaining 2MB page will be used
for the memmap of the next memory block. So one memory block will hold
the memmap of the two following memory blocks. Finally the pages of the
last-onlined memory block will get used for the next bigger allocations -
if any allocation is unmovable, all dependent memory blocks cannot get
unplugged and removed until that allocation is gone.
Note that with bigger memory blocks (e.g., 256MB), *all* memory
blocks are dependent and none can get unplugged again!
b) Experiment with memory intensive workload
I performed an experiment with an older version of this patch set (before
we used undo_isolate_page_range() in online_pages(): Hotplug 56GB to a VM
with an initial 4GB, onlining all memory to ZONE_NORMAL right from the
kernel when adding it. I then run various memory intensive workloads that
consume most system memory for a total of 45 minutes. Once finished, I
try to unplug as much memory as possible.
With this change, I am able to remove via virtio-mem (adding individual
128MB memory blocks) 413 out of 448 added memory blocks. Via individual
(256MB) DIMMs 380 out of 448 added memory blocks. (I don't have any
numbers without this patchset, but looking at the above example, it's at
most half of the 448 memory blocks for virtio-mem, and most probably none
for DIMMs).
Again, there are workloads that might behave very differently due to the
nature of ZONE_NORMAL.
This change also affects (besides memory onlining):
- Other users of undo_isolate_page_range(): Pages are always placed to the
tail.
-- When memory offlining fails
-- When memory isolation fails after having isolated some pageblocks
-- When alloc_contig_range() either succeeds or fails
- Other users of __putback_isolated_page(): Pages are always placed to the
tail.
-- Free page reporting
- Other users of __free_pages_core()
-- AFAIKs, any memory that is getting exposed to the buddy during boot.
IIUC we will now usually allocate memory from lower addresses within
a zone first (especially during boot).
- Other users of generic_online_page()
-- Hyper-V balloon
This patch (of 5):
Let's prepare for additional flags and avoid long parameter lists of
bools. Follow-up patches will also make use of the flags in
__free_pages_ok().
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Scott Cheloha <cheloha@linux.ibm.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Michal Hocko <mhocko@kernel.org>
Link: https://lkml.kernel.org/r/20201005121534.15649-1-david@redhat.com
Link: https://lkml.kernel.org/r/20201005121534.15649-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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