user/sven/linux.git/include/linux/mmzone.h, branch v5.4.90

mm: replace memmap_context by meminit_context

2020-10-07T06:01:29Z

commit c1d0da83358a2316d9be7f229f26126dbaa07468 upstream. Patch series "mm: fix memory to node bad links in sysfs", v3. Sometimes, firmware may expose interleaved memory layout like this: Early memory node ranges node 1: [mem 0x0000000000000000-0x000000011fffffff] node 2: [mem 0x0000000120000000-0x000000014fffffff] node 1: [mem 0x0000000150000000-0x00000001ffffffff] node 0: [mem 0x0000000200000000-0x000000048fffffff] node 2: [mem 0x0000000490000000-0x00000007ffffffff] In that case, we can see memory blocks assigned to multiple nodes in sysfs: $ ls -l /sys/devices/system/memory/memory21 total 0 lrwxrwxrwx 1 root root 0 Aug 24 05:27 node1 -> ../../node/node1 lrwxrwxrwx 1 root root 0 Aug 24 05:27 node2 -> ../../node/node2 -rw-r--r-- 1 root root 65536 Aug 24 05:27 online -r--r--r-- 1 root root 65536 Aug 24 05:27 phys_device -r--r--r-- 1 root root 65536 Aug 24 05:27 phys_index drwxr-xr-x 2 root root 0 Aug 24 05:27 power -r--r--r-- 1 root root 65536 Aug 24 05:27 removable -rw-r--r-- 1 root root 65536 Aug 24 05:27 state lrwxrwxrwx 1 root root 0 Aug 24 05:25 subsystem -> ../../../../bus/memory -rw-r--r-- 1 root root 65536 Aug 24 05:25 uevent -r--r--r-- 1 root root 65536 Aug 24 05:27 valid_zones The same applies in the node's directory with a memory21 link in both the node1 and node2's directory. This is wrong but doesn't prevent the system to run. However when later, one of these memory blocks is hot-unplugged and then hot-plugged, the system is detecting an inconsistency in the sysfs layout and a BUG_ON() is raised: kernel BUG at /Users/laurent/src/linux-ppc/mm/memory_hotplug.c:1084! LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries Modules linked in: rpadlpar_io rpaphp pseries_rng rng_core vmx_crypto gf128mul binfmt_misc ip_tables x_tables xfs libcrc32c crc32c_vpmsum autofs4 CPU: 8 PID: 10256 Comm: drmgr Not tainted 5.9.0-rc1+ #25 Call Trace: add_memory_resource+0x23c/0x340 (unreliable) __add_memory+0x5c/0xf0 dlpar_add_lmb+0x1b4/0x500 dlpar_memory+0x1f8/0xb80 handle_dlpar_errorlog+0xc0/0x190 dlpar_store+0x198/0x4a0 kobj_attr_store+0x30/0x50 sysfs_kf_write+0x64/0x90 kernfs_fop_write+0x1b0/0x290 vfs_write+0xe8/0x290 ksys_write+0xdc/0x130 system_call_exception+0x160/0x270 system_call_common+0xf0/0x27c This has been seen on PowerPC LPAR. The root cause of this issue is that when node's memory is registered, the range used can overlap another node's range, thus the memory block is registered to multiple nodes in sysfs. There are two issues here: (a) The sysfs memory and node's layouts are broken due to these multiple links (b) The link errors in link_mem_sections() should not lead to a system panic. To address (a) register_mem_sect_under_node should not rely on the system state to detect whether the link operation is triggered by a hot plug operation or not. This is addressed by the patches 1 and 2 of this series. Issue (b) will be addressed separately. This patch (of 2): The memmap_context enum is used to detect whether a memory operation is due to a hot-add operation or happening at boot time. Make it general to the hotplug operation and rename it as meminit_context. There is no functional change introduced by this patch Suggested-by: David Hildenbrand Signed-off-by: Laurent Dufour Signed-off-by: Andrew Morton Reviewed-by: David Hildenbrand Reviewed-by: Oscar Salvador Acked-by: Michal Hocko Cc: Greg Kroah-Hartman Cc: "Rafael J . Wysocki" Cc: Nathan Lynch Cc: Scott Cheloha Cc: Tony Luck Cc: Fenghua Yu Cc: Link: https://lkml.kernel.org/r/20200915094143.79181-1-ldufour@linux.ibm.com Link: https://lkml.kernel.org/r/20200915132624.9723-1-ldufour@linux.ibm.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: initialize deferred pages with interrupts enabled

2020-06-22T07:31:14Z

commit 3d060856adfc59afb9d029c233141334cfaba418 upstream. Initializing struct pages is a long task and keeping interrupts disabled for the duration of this operation introduces a number of problems. 1. jiffies are not updated for long period of time, and thus incorrect time is reported. See proposed solution and discussion here: lkml/20200311123848.118638-1-shile.zhang@linux.alibaba.com 2. It prevents farther improving deferred page initialization by allowing intra-node multi-threading. We are keeping interrupts disabled to solve a rather theoretical problem that was never observed in real world (See 3a2d7fa8a3d5). Let's keep interrupts enabled. In case we ever encounter a scenario where an interrupt thread wants to allocate large amount of memory this early in boot we can deal with that by growing zone (see deferred_grow_zone()) by the needed amount before starting deferred_init_memmap() threads. Before: [ 1.232459] node 0 initialised, 12058412 pages in 1ms After: [ 1.632580] node 0 initialised, 12051227 pages in 436ms Fixes: 3a2d7fa8a3d5 ("mm: disable interrupts while initializing deferred pages") Reported-by: Shile Zhang Signed-off-by: Pavel Tatashin Signed-off-by: Andrew Morton Reviewed-by: Daniel Jordan Reviewed-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Vlastimil Babka Cc: Dan Williams Cc: James Morris Cc: Kirill Tkhai Cc: Sasha Levin Cc: Yiqian Wei Cc: [4.17+] Link: http://lkml.kernel.org/r/20200403140952.17177-3-pasha.tatashin@soleen.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: memcg/slab: fix percpu slab vmstats flushing

2020-01-23T07:22:39Z

commit 4a87e2a25dc27131c3cce5e94421622193305638 upstream. Currently slab percpu vmstats are flushed twice: during the memcg offlining and just before freeing the memcg structure. Each time percpu counters are summed, added to the atomic counterparts and propagated up by the cgroup tree. The second flushing is required due to how recursive vmstats are implemented: counters are batched in percpu variables on a local level, and once a percpu value is crossing some predefined threshold, it spills over to atomic values on the local and each ascendant levels. It means that without flushing some numbers cached in percpu variables will be dropped on floor each time a cgroup is destroyed. And with uptime the error on upper levels might become noticeable. The first flushing aims to make counters on ancestor levels more precise. Dying cgroups may resume in the dying state for a long time. After kmem_cache reparenting which is performed during the offlining slab counters of the dying cgroup don't have any chances to be updated, because any slab operations will be performed on the parent level. It means that the inaccuracy caused by percpu batching will not decrease up to the final destruction of the cgroup. By the original idea flushing slab counters during the offlining should minimize the visible inaccuracy of slab counters on the parent level. The problem is that percpu counters are not zeroed after the first flushing. So every cached percpu value is summed twice. It creates a small error (up to 32 pages per cpu, but usually less) which accumulates on parent cgroup level. After creating and destroying of thousands of child cgroups, slab counter on parent level can be way off the real value. For now, let's just stop flushing slab counters on memcg offlining. It can't be done correctly without scheduling a work on each cpu: reading and zeroing it during css offlining can race with an asynchronous update, which doesn't expect values to be changed underneath. With this change, slab counters on parent level will become eventually consistent. Once all dying children are gone, values are correct. And if not, the error is capped by 32 * NR_CPUS pages per dying cgroup. It's not perfect, as slab are reparented, so any updates after the reparenting will happen on the parent level. It means that if a slab page was allocated, a counter on child level was bumped, then the page was reparented and freed, the annihilation of positive and negative counter values will not happen until the child cgroup is released. It makes slab counters different from others, and it might want us to implement flushing in a correct form again. But it's also a question of performance: scheduling a work on each cpu isn't free, and it's an open question if the benefit of having more accurate counters is worth it. We might also consider flushing all counters on offlining, not only slab counters. So let's fix the main problem now: make the slab counters eventually consistent, so at least the error won't grow with uptime (or more precisely the number of created and destroyed cgroups). And think about the accuracy of counters separately. Link: http://lkml.kernel.org/r/20191220042728.1045881-1-guro@fb.com Fixes: bee07b33db78 ("mm: memcontrol: flush percpu slab vmstats on kmem offlining") Signed-off-by: Roman Gushchin Acked-by: Johannes Weiner Acked-by: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm: thp: extract split_queue_* into a struct

2019-09-24T22:54:11Z

Patch series "Make deferred split shrinker memcg aware", v6. Currently THP deferred split shrinker is not memcg aware, this may cause premature OOM with some configuration. For example the below test would run into premature OOM easily: $ cgcreate -g memory:thp $ echo 4G > /sys/fs/cgroup/memory/thp/memory/limit_in_bytes $ cgexec -g memory:thp transhuge-stress 4000 transhuge-stress comes from kernel selftest. It is easy to hit OOM, but there are still a lot THP on the deferred split queue, memcg direct reclaim can't touch them since the deferred split shrinker is not memcg aware. Convert deferred split shrinker memcg aware by introducing per memcg deferred split queue. The THP should be on either per node or per memcg deferred split queue if it belongs to a memcg. When the page is immigrated to the other memcg, it will be immigrated to the target memcg's deferred split queue too. Reuse the second tail page's deferred_list for per memcg list since the same THP can't be on multiple deferred split queues. Make deferred split shrinker not depend on memcg kmem since it is not slab. It doesn't make sense to not shrink THP even though memcg kmem is disabled. With the above change the test demonstrated above doesn't trigger OOM even though with cgroup.memory=nokmem. This patch (of 4): Put split_queue, split_queue_lock and split_queue_len into a struct in order to reduce code duplication when we convert deferred_split to memcg aware in the later patches. Link: http://lkml.kernel.org/r/1565144277-36240-2-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi Suggested-by: "Kirill A . Shutemov" Acked-by: Kirill A. Shutemov Reviewed-by: Kirill Tkhai Cc: Johannes Weiner Cc: Michal Hocko Cc: Hugh Dickins Cc: Shakeel Butt Cc: David Rientjes Cc: Qian Cai Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm,thp: stats for file backed THP

2019-09-24T22:54:11Z

In preparation for non-shmem THP, this patch adds a few stats and exposes them in /proc/meminfo, /sys/bus/node/devices//meminfo, and /proc//task//smaps. This patch is mostly a rewrite of Kirill A. Shutemov's earlier version: https://lkml.kernel.org/r/20170126115819.58875-5-kirill.shutemov@linux.intel.com/ Link: http://lkml.kernel.org/r/20190801184244.3169074-5-songliubraving@fb.com Signed-off-by: Song Liu Acked-by: Rik van Riel Acked-by: Kirill A. Shutemov Acked-by: Johannes Weiner Cc: Hillf Danton Cc: Hugh Dickins Cc: William Kucharski Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: memcontrol: flush percpu slab vmstats on kmem offlining

2019-08-31T01:00:50Z

I've noticed that the "slab" value in memory.stat is sometimes 0, even if some children memory cgroups have a non-zero "slab" value. The following investigation showed that this is the result of the kmem_cache reparenting in combination with the per-cpu batching of slab vmstats. At the offlining some vmstat value may leave in the percpu cache, not being propagated upwards by the cgroup hierarchy. It means that stats on ancestor levels are lower than actual. Later when slab pages are released, the precise number of pages is substracted on the parent level, making the value negative. We don't show negative values, 0 is printed instead. To fix this issue, let's flush percpu slab memcg and lruvec stats on memcg offlining. This guarantees that numbers on all ancestor levels are accurate and match the actual number of outstanding slab pages. Link: http://lkml.kernel.org/r/20190819202338.363363-3-guro@fb.com Fixes: fb2f2b0adb98 ("mm: memcg/slab: reparent memcg kmem_caches on cgroup removal") Signed-off-by: Roman Gushchin Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

libnvdimm/pfn: stop padding pmem namespaces to section alignment

2019-07-19T00:08:07Z

Now that the mm core supports section-unaligned hotplug of ZONE_DEVICE memory, we no longer need to add padding at pfn/dax device creation time. The kernel will still honor padding established by older kernels. Link: http://lkml.kernel.org/r/156092356588.979959.6793371748950931916.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Jeff Moyer Tested-by: Aneesh Kumar K.V [ppc64] Cc: David Hildenbrand Cc: Jane Chu Cc: Jérôme Glisse Cc: Jonathan Corbet Cc: Logan Gunthorpe Cc: Michal Hocko Cc: Mike Rapoport Cc: Oscar Salvador Cc: Pavel Tatashin Cc: Toshi Kani Cc: Vlastimil Babka Cc: Wei Yang Cc: Jason Gunthorpe Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: kill is_dev_zone() helper

2019-07-19T00:08:07Z

Given there are no more usages of is_dev_zone() outside of 'ifdef CONFIG_ZONE_DEVICE' protection, kill off the compilation helper. Link: http://lkml.kernel.org/r/156092353211.979959.1489004866360828964.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reviewed-by: Oscar Salvador Reviewed-by: Pavel Tatashin Reviewed-by: Wei Yang Acked-by: David Hildenbrand Tested-by: Aneesh Kumar K.V [ppc64] Cc: Michal Hocko Cc: Logan Gunthorpe Cc: Jane Chu Cc: Jeff Moyer Cc: Jérôme Glisse Cc: Jonathan Corbet Cc: Mike Rapoport Cc: Toshi Kani Cc: Vlastimil Babka Cc: Jason Gunthorpe Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/sparsemem: add helpers track active portions of a section at boot

2019-07-19T00:08:07Z

Prepare for hot{plug,remove} of sub-ranges of a section by tracking a sub-section active bitmask, each bit representing a PMD_SIZE span of the architecture's memory hotplug section size. The implications of a partially populated section is that pfn_valid() needs to go beyond a valid_section() check and either determine that the section is an "early section", or read the sub-section active ranges from the bitmask. The expectation is that the bitmask (subsection_map) fits in the same cacheline as the valid_section() / early_section() data, so the incremental performance overhead to pfn_valid() should be negligible. The rationale for using early_section() to short-ciruit the subsection_map check is that there are legacy code paths that use pfn_valid() at section granularity before validating the pfn against pgdat data. So, the early_section() check allows those traditional assumptions to persist while also permitting subsection_map to tell the truth for purposes of populating the unused portions of early sections with PMEM and other ZONE_DEVICE mappings. Link: http://lkml.kernel.org/r/156092350874.979959.18185938451405518285.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Qian Cai Tested-by: Jane Chu Tested-by: Aneesh Kumar K.V [ppc64] Reviewed-by: Oscar Salvador Cc: Michal Hocko Cc: Vlastimil Babka Cc: Logan Gunthorpe Cc: Pavel Tatashin Cc: David Hildenbrand Cc: Jeff Moyer Cc: Jérôme Glisse Cc: Jonathan Corbet Cc: Mike Rapoport Cc: Toshi Kani Cc: Wei Yang Cc: Jason Gunthorpe Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/sparsemem: introduce a SECTION_IS_EARLY flag

2019-07-19T00:08:07Z

In preparation for sub-section hotplug, track whether a given section was created during early memory initialization, or later via memory hotplug. This distinction is needed to maintain the coarse expectation that pfn_valid() returns true for any pfn within a given section even if that section has pages that are reserved from the page allocator. For example one of the of goals of subsection hotplug is to support cases where the system physical memory layout collides System RAM and PMEM within a section. Several pfn_valid() users expect to just check if a section is valid, but they are not careful to check if the given pfn is within a "System RAM" boundary and instead expect pgdat information to further validate the pfn. Rather than unwind those paths to make their pfn_valid() queries more precise a follow on patch uses the SECTION_IS_EARLY flag to maintain the traditional expectation that pfn_valid() returns true for all early sections. Link: https://lore.kernel.org/lkml/1560366952-10660-1-git-send-email-cai@lca.pw/ Link: http://lkml.kernel.org/r/156092350358.979959.5817209875548072819.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Reported-by: Qian Cai Tested-by: Aneesh Kumar K.V [ppc64] Reviewed-by: Oscar Salvador Cc: Michal Hocko Cc: Logan Gunthorpe Cc: David Hildenbrand Cc: Pavel Tatashin Cc: Jane Chu Cc: Jeff Moyer Cc: Jérôme Glisse Cc: Jonathan Corbet Cc: Mike Rapoport Cc: Toshi Kani Cc: Vlastimil Babka Cc: Wei Yang Cc: Jason Gunthorpe Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds