linux/mm/memory_hotplug.c, branch v5.7

mm/memory_hotplug: add pgprot_t to mhp_params

2020-04-10T22:36:21Z

devm_memremap_pages() is currently used by the PCI P2PDMA code to create struct page mappings for IO memory. At present, these mappings are created with PAGE_KERNEL which implies setting the PAT bits to be WB. However, on x86, an mtrr register will typically override this and force the cache type to be UC-. In the case firmware doesn't set this register it is effectively WB and will typically result in a machine check exception when it's accessed. Other arches are not currently likely to function correctly seeing they don't have any MTRR registers to fall back on. To solve this, provide a way to specify the pgprot value explicitly to arch_add_memory(). Of the arches that support MEMORY_HOTPLUG: x86_64, and arm64 need a simple change to pass the pgprot_t down to their respective functions which set up the page tables. For x86_32, set the page tables explicitly using _set_memory_prot() (seeing they are already mapped). For ia64, s390 and sh, reject anything but PAGE_KERNEL settings -- this should be fine, for now, seeing these architectures don't support ZONE_DEVICE. A check in __add_pages() is also added to ensure the pgprot parameter was set for all arches. Signed-off-by: Logan Gunthorpe Signed-off-by: Andrew Morton Acked-by: David Hildenbrand Acked-by: Michal Hocko Acked-by: Dan Williams Cc: Andy Lutomirski Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christoph Hellwig Cc: Dave Hansen Cc: Eric Badger Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Link: http://lkml.kernel.org/r/20200306170846.9333-7-logang@deltatee.com Signed-off-by: Linus Torvalds

mm/memory_hotplug: rename mhp_restrictions to mhp_params

2020-04-10T22:36:21Z

The mhp_restrictions struct really doesn't specify anything resembling a restriction anymore so rename it to be mhp_params as it is a list of extended parameters. Signed-off-by: Logan Gunthorpe Signed-off-by: Andrew Morton Reviewed-by: David Hildenbrand Reviewed-by: Dan Williams Acked-by: Michal Hocko Cc: Andy Lutomirski Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christoph Hellwig Cc: Dave Hansen Cc: Eric Badger Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jason Gunthorpe Cc: Michael Ellerman Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Link: http://lkml.kernel.org/r/20200306170846.9333-3-logang@deltatee.com Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: use __pfn_to_section() instead of open-coding

2020-04-07T17:43:41Z

Use __pfn_to_section() API instead of open-coding for better code readability. Signed-off-by: chenqiwu Signed-off-by: Andrew Morton Acked-by: David Hildenbrand Link: http://lkml.kernel.org/r/1584345134-16671-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Linus Torvalds

mm/memory_hotplug: allow to specify a default online_type

2020-04-07T17:43:41Z

For now, distributions implement advanced udev rules to essentially - Don't online any hotplugged memory (s390x) - Online all memory to ZONE_NORMAL (e.g., most virt environments like hyperv) - Online all memory to ZONE_MOVABLE in case the zone imbalance is taken care of (e.g., bare metal, special virt environments) In summary: All memory is usually onlined the same way, however, the kernel always has to ask user space to come up with the same answer. E.g., Hyper-V always waits for a memory block to get onlined before continuing, otherwise it might end up adding memory faster than onlining it, which can result in strange OOM situations. This waiting slows down adding of a bigger amount of memory. Let's allow to specify a default online_type, not just "online" and "offline". This allows distributions to configure the default online_type when booting up and be done with it. We can now specify "offline", "online", "online_movable" and "online_kernel" via - "memhp_default_state=" on the kernel cmdline - /sys/devices/system/memory/auto_online_blocks just like we are able to specify for a single memory block via /sys/devices/system/memory/memoryX/state Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Wei Yang Reviewed-by: Baoquan He Acked-by: Michal Hocko Acked-by: Pankaj Gupta Cc: Greg Kroah-Hartman Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Wei Yang Cc: Benjamin Herrenschmidt Cc: Eduardo Habkost Cc: Haiyang Zhang Cc: Igor Mammedov Cc: "K. Y. Srinivasan" Cc: Michael Ellerman Cc: Paul Mackerras Cc: Stephen Hemminger Cc: Vitaly Kuznetsov Cc: Wei Liu Cc: Yumei Huang Link: http://lkml.kernel.org/r/20200317104942.11178-9-david@redhat.com Signed-off-by: Linus Torvalds

mm/memory_hotplug: convert memhp_auto_online to store an online_type

2020-04-07T17:43:40Z

... and rename it to memhp_default_online_type. This is a preparation for more detailed default online behavior. Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Wei Yang Reviewed-by: Baoquan He Acked-by: Michal Hocko Acked-by: Pankaj Gupta Cc: Greg Kroah-Hartman Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Wei Yang Cc: Benjamin Herrenschmidt Cc: Eduardo Habkost Cc: Haiyang Zhang Cc: Igor Mammedov Cc: "K. Y. Srinivasan" Cc: Michael Ellerman Cc: Paul Mackerras Cc: Stephen Hemminger Cc: Vitaly Kuznetsov Cc: Wei Liu Cc: Yumei Huang Link: http://lkml.kernel.org/r/20200317104942.11178-8-david@redhat.com Signed-off-by: Linus Torvalds

mm/memory_hotplug: unexport memhp_auto_online

2020-04-07T17:43:40Z

All in-tree users except the mm-core are gone. Let's drop the export. Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Wei Yang Reviewed-by: Baoquan He Acked-by: Michal Hocko Acked-by: Pankaj Gupta Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Benjamin Herrenschmidt Cc: Eduardo Habkost Cc: Greg Kroah-Hartman Cc: Haiyang Zhang Cc: Igor Mammedov Cc: "K. Y. Srinivasan" Cc: Michael Ellerman Cc: Paul Mackerras Cc: Stephen Hemminger Cc: Vitaly Kuznetsov Cc: Wei Liu Cc: Yumei Huang Link: http://lkml.kernel.org/r/20200317104942.11178-7-david@redhat.com Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: cleanup __add_pages()

2020-04-07T17:43:40Z

Let's drop the basically unused section stuff and simplify. The logic now matches the logic in __remove_pages(). Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Baoquan He Reviewed-by: Wei Yang Cc: Segher Boessenkool Cc: Oscar Salvador Cc: Michal Hocko Cc: Dan Williams Link: http://lkml.kernel.org/r/20200228095819.10750-3-david@redhat.com Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: simplify calculation of number of pages in __remove_pages()

2020-04-07T17:43:40Z

In commit 52fb87c81f11 ("mm/memory_hotplug: cleanup __remove_pages()"), we cleaned up __remove_pages(), and introduced a shorter variant to calculate the number of pages to the next section boundary. Turns out we can make this calculation easier to read. We always want to have the number of pages (> 0) to the next section boundary, starting from the current pfn. We'll clean up __remove_pages() in a follow-up patch and directly make use of this computation. Suggested-by: Segher Boessenkool Signed-off-by: David Hildenbrand Signed-off-by: Andrew Morton Reviewed-by: Baoquan He Reviewed-by: Wei Yang Cc: Oscar Salvador Cc: Michal Hocko Cc: Dan Williams Link: http://lkml.kernel.org/r/20200228095819.10750-2-david@redhat.com Signed-off-by: Linus Torvalds

mm/memory_hotplug.c: only respect mem= parameter during boot stage

2020-04-07T17:43:40Z

In commit 357b4da50a62 ("x86: respect memory size limiting via mem= parameter") a global varialbe max_mem_size is added to store the value parsed from 'mem= ', then checked when memory region is added. This truly stops those DIMMs from being added into system memory during boot-time. However, it also limits the later memory hotplug functionality. Any DIMM can't be hotplugged any more if its region is beyond the max_mem_size. We will get errors like: [ 216.387164] acpi PNP0C80:02: add_memory failed [ 216.389301] acpi PNP0C80:02: acpi_memory_enable_device() error [ 216.392187] acpi PNP0C80:02: Enumeration failure This will cause issue in a known use case where 'mem=' is added to the hypervisor. The memory that lies after 'mem=' boundary will be assigned to KVM guests. After commit 357b4da50a62 merged, memory can't be extended dynamically if system memory on hypervisor is not sufficient. So fix it by also checking if it's during boot-time restricting to add memory. Otherwise, skip the restriction. And also add this use case to document of 'mem=' kernel parameter. Fixes: 357b4da50a62 ("x86: respect memory size limiting via mem= parameter") Signed-off-by: Baoquan He Signed-off-by: Andrew Morton Reviewed-by: Juergen Gross Acked-by: Michal Hocko Cc: Ingo Molnar Cc: William Kucharski Cc: David Hildenbrand Cc: Balbir Singh Link: http://lkml.kernel.org/r/20200204050643.20925-1-bhe@redhat.com Signed-off-by: Linus Torvalds

mm: code cleanup for MADV_FREE

2020-04-07T17:43:38Z

Some comments for MADV_FREE is revised and added to help people understand the MADV_FREE code, especially the page flag, PG_swapbacked. This makes page_is_file_cache() isn't consistent with its comments. So the function is renamed to page_is_file_lru() to make them consistent again. All these are put in one patch as one logical change. Suggested-by: David Hildenbrand Suggested-by: Johannes Weiner Suggested-by: David Rientjes Signed-off-by: "Huang, Ying" Signed-off-by: Andrew Morton Acked-by: Johannes Weiner Acked-by: David Rientjes Acked-by: Michal Hocko Acked-by: Pankaj Gupta Acked-by: Vlastimil Babka Cc: Dave Hansen Cc: Mel Gorman Cc: Minchan Kim Cc: Hugh Dickins Cc: Rik van Riel Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com Signed-off-by: Linus Torvalds